# II. Recommendations for prevention of infections in health care
. Summary of suggested work restrictions for health care personnel exposed to or infected with infectious diseases of importance in health care settings, in the absence of state and local regulations 299 Table 4. Recommendation for postexposure prophylaxis for percutaneous or permucosal exposure to hepatitis B virus, United States 303 Table 5. Selected reported etiologic agents causing community or nosocomially acquired gastrointestinal 307 infections in developed countries Table 6. Pregnant health care personnel: Pertinent facts to guide management of occupational exposures to 322 infectious agents Appendix A. Recommended readings for infection control in health care personnel 354
Part I. Infection control issues for health care personnel: An overview

# A. EXECUTIVE SUMMARY
This guideline updates and replaces the previ ous edition of the Centers for Disease Control and Prevention (CDC) "Guideline for Infection Control in Hospital Personnel," published in 1983. The revised guideline, designed to provide methods for reducing the transmission of infections from patients to health care personnel and from per sonnel to patients, also provides an overview of the evidence for recommendations considered prudent by consensus of the Hospital Infection Control Practices Advisory Committee members. A working draft of this guideline was also reviewed by experts in infection control, occupa tional health, and infectious diseases; however, all recommendations contained in the guideline may not reflect the opinion of all reviewers.
This document focuses on the epidemiology of and preventive strategies for infections known to be transmitted in health care settings and those for which there are adequate scientific data on which to base recommendations for prevention.
The prevention strategies addressed in this docu ment include immunizations for vaccine-pre ventable diseases, isolation precautions to pre vent exposures to infectious agents, management of health care personnel exposure to infected per sons, including postexposure prophylaxis, and work restrictions for exposed or infected health care personnel. In addition, because latex barri ers are frequently used to protect personnel against transmission of infectious agents, this guideline addresses issues related to latex hyper sensitivity and provides recommendations to pre vent sensitization and reactions among health care personnel.

# B. INTRODUCTION
In the United States, there are an estimated 8.8 million persons who work in health care profes sions and about 6 million persons work in more than 6000 hospitals. However, health care is increasingly being provided outside hospitals in facilities such as nursing homes, freestanding sur gical and outpatient centers, emergency care clin ics, and in patients' homes or during prehospital emergency care. Hospital-based personnel and personnel who provide health care outside hospi tals may acquire infections from or transmit infections to patients, other personnel, household members, or other community contacts. 1,2 In this document, the term health care person nel refers to all paid and unpaid persons work ing in health care settings who have the poten tial for exposure to infectious materials, includ ing body substances, contaminated medical supplies and equipment, contaminated environ mental surfaces, or contaminated air. These personnel may include but are not limited to emergency medical service personnel, dental personnel, laboratory personnel, autopsy per sonnel, nurses, nursing assistants, physicians, technicians, therapists, pharmacists, students and trainees, contractual staff not employed by the health care facility, and persons not directly involved in patient care but potentially exposed to infectious agents (e.g., clerical, dietary, housekeeping, maintenance, and volunteer per sonnel). In general, health care personnel in or outside hospitals who have contact with patients, body fluids, or specimens have a high er risk of acquiring or transmitting infections than do other health care personnel who have only brief casual contact with patients and their environment (e.g., beds, furniture, bathrooms, food trays, medical equipment).

# AJIC June 1998
Throughout this document, terms are used to describe routes of transmission of infections. These terms have been fully described in the "Guideline for Isolation Precautions in Hospitals." 3 They are summarized as follows: direct contact refers to body surface-to-body sur face contact and physical transfer of microorgan isms between a susceptible host and an infected or colonized person (e.g., while performing oral care or procedures); indirect contact refers to con tact of a susceptible host with a contaminated object (e.g., instruments, hands); droplet contact refers to conjunctival, nasal, or oral mucosa con tact with droplets containing microorganisms generated from an infected person (by coughing, sneezing, and talking, or during certain proce dures such as suctioning and bronchoscopy) that are propelled a short distance; airborne transmis sion refers to contact with droplet nuclei contain ing microorganisms that can remain suspended in the air for long periods or to contact with dust particles containing an infectious agent that can be widely disseminated by air currents; and, final ly, common vehicle transmission refers to contact with contaminated items such as food, water, medications, devices, and equipment.
In 1983 the CDC published the "Guideline for Infection Control in Hospital Personnel." 4 The document focused on the prevention of infec tions known to be transmitted to and from health care personnel. This revision of the guide line has been expanded to include (a) recom mendations for non-patient care personnel, both in and outside hospitals, (b) management of exposures, (c) prevention of transmission of infections in microbiologic and biomedical labo ratories, and, because of the common use of latex barriers to prevent infections, (d) preven tion of latex hypersensitivity reactions. As in the 1983 guideline, readers are frequently referred to the "Guideline for Isolation Precautions in Hospitals" 3 and other published guidelines and recommendations for precautions that health care personnel may use when caring for patients or handling patient equipment or specimens. 5,6

# C. INFECTION CONTROL OBJECTIVES FOR A PERSONNEL HEALTH SERVICE
The infection control objectives of the person nel health service should be an integral part of a health care organization's general program for infection control. The objectives usually include the following: (a) educating personnel about the principles of infection control and stressing indi vidual responsibility for infection control, (b) col laborating with the infection control department in monitoring and investigating potentially harm ful infectious exposures and outbreaks among personnel, (c) providing care to personnel for work-related illnesses or exposures, (d) identify ing work-related infection risks and instituting appropriate preventive measures, and (e) contain ing costs by preventing infectious diseases that result in absenteeism and disability. These objec tives cannot be met without the support of the health care organization's administration, med ical staff, and other health care personnel. Documents that provide more detailed informa tion regarding infection control issues for person nel health are listed in Appendix A.

# D. ELEMENTS OF A PERSONNEL HEALTH SERVICE FOR INFECTION CONTROL
Certain elements are necessary to attain the infection control goals of a personnel health ser vice: (a) coordination with other departments, (b) medical evaluations, (c) health and safety educa tion, (d) immunization programs, (e) manage ment of job-related illnesses and exposures to infectious diseases, including policies for work restrictions for infected or exposed personnel, (f) counseling services for personnel on infection risks related to employment or special conditions, and (g) maintenance and confidentiality of per sonnel health records.
The organization of a personnel health service may be influenced by the size of the institution, the number of personnel, and the services offered. To ensure that contractual personnel who are not paid by the health care facility receive appropriate personnel health services, contractual agreements with their employers should contain provisions consistent with the policies of the facility that uses those employees. Personnel with specialized training and qualifications in occupational health can facilitate the provision of effective services.

# Coordination with other departments
For infection control objectives to be achieved, the activities of the personnel health service must be coordinated with infection control and other appropriate departmental personnel. This coordi nation will help ensure adequate surveillance of infections in personnel and provision of preven tive services. Coordinating activities will also help to ensure that investigations of exposures and out breaks are conducted efficiently and preventive measures implemented promptly.
CDC Personnel Health Guideline 293

# Medical evaluations
Medical evaluations before placement can ensure that personnel are not placed in jobs that would pose undue risk of infection to them, other personnel, patients, or visitors. An important com ponent of the placement evaluation is a health inventory. This usually includes determining immunization status and obtaining histories of any conditions that might predispose personnel to acquiring or transmitting communicable diseases. This information will assist in decisions about immunizations or postexposure management.
A physical examination, another component of the medical evaluation, can be used to screen personnel for conditions that might increase the risk of transmitting or acquiring work-relat ed diseases and can serve as a baseline for determining whether future diseases are work related. However, the cost-effectiveness of rou tine physical examinations, including laborato ry testing (such as complete blood cell counts, serologic tests for syphilis, urinalysis, and chest radiographs) and screening for enteric or other pathogens for infection control purposes, has not been demonstrated. Conversely, screening for some vaccine-preventable diseases, such as hepatitis B, measles, mumps, rubella, or vari cella, may be cost-effective. In general, the health inventory can be used to guide decisions regarding physical examinations or laboratory tests. However, some local public health ordi nances may mandate that certain screening procedures be used.
Periodic evaluations may be done as indicat ed for job reassignment, for ongoing programs (e.g., TB screening), or for evaluation of workrelated problems.

# Personnel health and safety education
Personnel are more likely to comply with an infection control program if they understand its rationale. Thus, personnel education is a cardinal element of an effective infection control program. Clearly written policies, guidelines, and proce dures ensure uniformity, efficiency, and effective coordination of activities. However, because the risk of infection varies by job category, infection control education should be modified accordingly. In addition, some personnel may need specialized education on infection risks related to their employment and on preventive measures that will reduce those risks. Furthermore, educational materials need to be appropriate in content and vocabulary to the educational level, literacy, and are also likely to be susceptible to rubella least 1 mo mentation of (a) receipt of (including HIV-infect and/or mumps; persons vaccinated later two doses of live vaccine on ed persons with between 1963 and 1967 with (a) a killed or after their 1st birthday, (b) severe immunosup measles vaccine alone, (b) killed vaccine physician-diagnosed pression) history of followed by live vaccine, or (c) a vaccine measles, or (c) laboratory anaphylactic reac of unknown type should be revaccinated evidence of immunity; vac tions after gelatin with two doses of live measles vaccine cine should be considered ingestion or receipt for all personnel, including of neomycin; or those born before 1957, who recent receipt of have no proof of immunity immune globulin Mumps live-One dose SC; Health care personnel Pregnancy; immuno-MMR is the vaccine of choice if recipients virus vaccine no booster believed to be susceptible compromised- state; are also likely to be susceptible to can be vaccinated; adults history of anaphylac measles and rubella born before 1957 can be tic reaction after considered immune gelatin ingestion or receipt of neomycin Rubella live-One dose SC; Health care personnel, both Pregnancy; immuno-Women pregnant when vaccinated or who virus vaccine no booster male and female, who lack compromised- state; become pregnant within 3 mo of vaccina documentation of receipt of history of anaphylac tion should be counseled on the theoretic live vaccine on or after their tic reaction after risks to the fetus, the risk of rubella vac 1st birthday, or of laboratory receipt of neomycin cine-associated malformations in these evidence of immunity; adults women is negligible; MMR is the vaccine born before 1957 can be of choice if recipients are also likely to be considered immune, except susceptible to measles or mumps women of childbearing age

# Immunization programs
Ensuring that personnel are immune to vac cine-preventable diseases is an essential part of successful personnel health programs. Optimal use of vaccines can prevent transmission of vac cine-preventable diseases and eliminate unneces sary work restriction. Prevention of illness through comprehensive personnel immunization programs is far more cost-effective than case management and outbreak control. Mandatory immunization programs, which include both newly hired and currently employed persons, are more effective than voluntary programs in ensur ing that susceptible persons are vaccinated. 7 National guidelines for immunization of and postexposure prophylaxis for health care person nel are provided by the U.S. Public Health Service's Advisory Committee on Immunization Practices (ACIP; Table 1). 8,9 ACIP guidelines also contain (a) detailed information on the epidemi ology of vaccine-preventable diseases, (b) data on the safety and efficacy of vaccines and immune globulin preparations,  and (c) recommenda tions for immunization of immunocompromised persons- (Table 2). 16,23 The recommendations in this guideline have been adapted from the ACIP recommendations. 9 In addition, individual states and professional organizations have regulations or recommendations on the vaccination of health care personnel. 24 Decisions about which vaccines to include in immunization programs have been made by con sidering (a) the likelihood of personnel exposure to vaccine-preventable diseases and the potential con sequences of not vaccinating personnel, (b) the nature of employment (type of contact with patients and their environment), and (c) the characteristics of the patient population within the health care organization. Immunization of personnel before they enter high-risk situations is the most efficient and effective use of vaccines in health care settings.
Screening tests are available to determine sus ceptibility to certain vaccine-preventable diseases *The term immunocompromised includes persons who are immunocompromised from immune deficiency diseases, HIV infection, leukemia, lymphoma, or generalized malig nancy, or immunosuppressed as a result of therapy with cor ticosteroids, alkylating drugs, antimetabolites, or radiation.  (e.g., hepatitis B, measles, mumps, rubella, and varicella). Such screening programs need to be combined with tracking systems to ensure accu rate maintenance of personnel immunization records. Accurate immunization records ensure that susceptible personnel are promptly identified and appropriately vaccinated.

# CDC Personnel Health Guideline 297

# Management of job-related illnesses and exposures
Primary functions of the personnel health ser vice are to arrange for prompt diagnosis and man agement of job-related illnesses and to provide appropriate postexposure prophylaxis after jobrelated exposures.
It is the responsibility of the health care orga nization to implement measures to prevent fur ther transmission of infection, which some times warrants exclusion of personnel from work or patient contact. 25 Decisions on work restrictions are based on the mode of transmis sion and the epidemiology of the disease (Table 3). The term exclude from duty in this document should be interpreted as exclusion from the health care facility and from health care activi ties outside the facility. Personnel who are excluded should avoid contact with susceptible persons both in the facility and in the commu nity. Exclusion policies should include a state ment of authority defining who may exclude personnel. The policies also need to be designed to encourage personnel to report their illnesses or exposures and not to penalize them with loss of wages, benefits, or job status. Workers' com pensation laws do not cover exclusion from duty for exposures to infectious diseases; poli cies therefore should include a method for pro viding wages during the period that personnel are not able to work. In addition, exclusion policies must be enforceable and all personnel, especially department heads, supervisors, and nurse managers, should know which infections may warrant exclusion and where to report the illnesses 24 hours a day. Health care personnel who have contact with infectious patients out side of hospitals also need to be included in the postexposure program and encouraged to report any suspected or known exposures promptly. Notification of emergency-response personnel possibly exposed to selected infec tious disease is mandatory (1990 Ryan White Act, Subtitle B, 42 USC 300ff-80).
CDC Personnel Health Guideline 299

# Health counseling
Access to adequate health counseling for per sonnel is another crucial element of an effective personnel health service. Health counseling allows personnel to receive individually targeted information regarding (a) the risk and prevention of occupationally acquired infections, (b) the risk of illness or other adverse outcome after expo sures, (c) management of exposures, including the risks and benefits of postexposure prophylaxis regimens, and (d) the potential consequences of exposures or communicable diseases for family members, patients, or other personnel, both inside and outside the health care facility.

# Maintenance of records, data management, and confidentiality
Maintenance of records on medical evaluations, immunizations, exposures, postexposure prophy laxis, and screening tests in a retrievable, prefer ably computerized, database allows efficient mon itoring of the health status of personnel. Such record keeping also helps to ensure that the orga nization will provide consistent and appropriate services to health care personnel.
Individual records for all personnel should be maintained in accordance with the Occu pational Safety and Health Administration (OSHA) medical records standard, which requires the employer to retain records, main tain employee confidentiality, and provide records to employees when they ask to review them. 26 In addition, the 1991 OSHA "Occu pational Exposure to Bloodborne Pathogens; Final Rule" 27 requires employers, including health care facilities, to establish and maintain an accurate record for each employee with occu pational exposure to bloodborne pathogens. The standard also requires that each employer ensure that the employee medical records are (a) kept confidential, (b) not disclosed or report ed without the employee's express written con sent to any person within or outside the work place, except as required by law, and (c) main tained by the employer for at least the duration of the worker's employment plus 30 years.
OSHA's record keeping regulation also requires employers to record work-related injuries and ill nesses on the OSHA 200 log and the OSHA 101 form. The records include all occupational fatali ties, all occupational illnesses, and occupational injuries that result in loss of consciousness, restriction of work or motion, transfer to another job, or medical treatment beyond first aid. Infectious diseases are recordable if they are work related and result in illness. 28 More recently, OSHA developed policies that require the recording of positive tuberculin skintest results. 29 It would be beneficial to health care organizations and personnel if the principles of record keeping and confidentiality mandated by OSHA were to be expanded to other work-related exposures and incidents, immunizations, TB screening, and investigation and management of nosocomial outbreaks.

# E. EPIDEMIOLOGY AND CONTROL OF SELECTED INFECTIONS TRANSMITTED AMONG HEALTH CARE PERSONNEL AND PATIENTS
Almost any transmissible infection may occur in the community at large or within health care organizations and can affect both personnel and patients. Only those infectious diseases that occur frequently in the health care setting or are most important to personnel are discussed here.

# Bloodborne pathogens a. Overview
Assessment of the risk and prevention of trans mission of bloodborne pathogens, such as hepati tis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV), in health care settings are based on information from a variety of sources, including surveillance and investigation of suspected cases of transmission to health care personnel and patients, seropreva lence surveys of health care personnel and patients, and studies of the risk of seroconversion after exposure to blood or other body fluids from infected persons. In this document, the emphasis of the discussion of bloodborne pathogens will be on patient-to-personnel transmission.
The CDC has periodically issued and updated recommendations for prevention of transmission of bloodborne pathogens in health care settings; these provide detailed information and guid ance.  Also, in 1991 OSHA published a bloodborne pathogen standard that was based on the concept of universal precautions to prevent occu pational exposure to bloodborne pathogens. 27 The use of standard precautions (which incorporates universal precautions), including appropriate handwashing and barrier precautions, will reduce contact with blood and body fluids. 3,30,31,41 The use of engineering controls (e.g., safety devices) and changes in work practices (e.g., techniques to reduce handling of sharp instruments) can reduce the frequency of percutaneous injuries. 41,42 In set tings such as the operating room, changes in AJIC June 1998 instrument design and techniques for performing surgical procedures and modified personal barri ers have been shown to reduce blood contacts. 43,44 Despite adherence to standard precautions and implementation of some new techniques and devices, percutaneous injuries continue to occur. This is of concern because percutaneous injuries represent the greatest risk of transmission of bloodborne pathogens to health care personnel. 45 Only a few studies evaluating a limited number of safety devices have demonstrated a reduction in percutaneous injuries among health care work ers. 46,47 This document will not address the use of safety devices, because the Public Health Service is assessing the need for further guidance on selection, implementation, and evaluation of such devices in health care settings.
The risk posed to patients by health care per sonnel infected with bloodborne pathogens such as HBV and HIV has been the subject of much concern and debate. There are no data to indi cate that infected workers who do not perform invasive procedures pose a risk to patients. Consequently, work restrictions for these work ers are not appropriate. However, the extent to which infected workers who perform certain types of invasive procedures pose a risk to patients and the restrictions that should be imposed on these workers have been much more controversial. In 1991, CDC recommendations on this issue were published. 48 Subsequently, Congress mandated that each state implement the CDC guidelines or equivalent as a condition for continued federal public health funding to that state. Although all states have complied with this mandate, there is a fair degree of state-to state variation regarding specific provisions. Local or state public health officials should be contacted to determine the regulations or rec ommendations applicable in a given area. CDC is currently in the process of reviewing relevant data regarding health care personnel-to-patient transmission of bloodborne pathogens.

# b. Hepatitis B
Nosocomial transmission of HBV is a serious risk for health care personnel.  Approximately 1000 health care personnel were estimated to have become infected with HBV in 1994. This 90% decline since 1985 is attributable to the use of vaccine and adherence to other preventive mea sures (e.g., standard precautions). 54 During the past decade, an estimated 100 to 200 health care personnel annually have died of occupationally acquired HBV infection. 54 The risk of acquiring CDC Personnel Health Guideline 303 HBV infection from occupational exposure is dependent on the nature and frequency of expo sure to blood or to body fluids containing blood. 49,53 The risk of infection is at least 30% after a percutaneous exposure to blood from a hepatitis B e antigen-seropositive source. 54 HBV is transmitted by percutaneous or mucosal exposure to blood and serum-derived body fluids from persons who have either acute or chronic HBV infection. The incubation peri od is 45 to 180 days (average 60 to 90 days). Any person seropositive for hepatitis B surface anti gen (HBsAg) is potentially infectious.
Hepatitis B vaccination of health care personnel who have contact with blood and body fluids can prevent transmission of HBV and is strongly rec ommended. 9,10,40 The OSHA bloodborne pathogen standard mandates that hepatitis B vaccine be made available, at the employer's expense, to all health care personnel with occupational exposure to blood or other potentially infectious materials. 27 Provision of vaccine during training of health care professionals before such blood exposure occurs may both increase the vaccination rates among personnel and prevent infection among trainees, who are at increased risk for unintentional injuries while they are learning techniques.
Prevaccination serologic screening for suscepti bility to HBV infection is not indicated for per sons being vaccinated, unless the health care organization considers such screening to be costeffective. Postvaccination screening for antibody to HBsAg (anti-HBs) is advised for personnel at ongoing risk for blood exposure to determine whether response to vaccinations has occurred and to aid in determining the appropriate postex posure prophylaxis or the need for revaccination. Personnel who do not respond to or do not com plete the primary vaccination series should be revaccinated with a second three-dose vaccine series or evaluated to determine whether they are HBsAg seropositive. Revaccinated persons should be tested for anti-HBs at the completion of the second vaccine series. 9 If they do not respond, no further vaccination series should be given and they should be evaluated for the presence of HBsAg (possible chronic HBV infection). No spe cific work restrictions are recommended for nonresponders; in the event of percutaneous exposure to blood or body fluids, however, they should see their health care providers as soon as possible to evaluate the need for postexposure prophylaxis. Personnel in chronic dialysis centers who do not respond to vaccine need to be screened for HBsAg and anti-HBs every 6 months. 55 Vaccine-induced antibodies decline gradually with time, and as many as 60% of those who ini tially respond to vaccination will lose detectable anti-HBs by 8 years. 56 Booster doses of vaccine are not routinely recommended, because per sons who respond to the initial vaccine series remain protected against clinical hepatitis and chronic infection even when their anti-HBs lev els become low or undetectable. 57 The need for postexposure prophylaxis, vacci nation, or both depends on the HBsAg status of the source of the exposure as well as the immu nization status of the person exposed (Table 4). 40 Vaccine should be offered after any exposure in an unvaccinated person; if the source is known to be HBsAg seropositive, hepatitis B immune glob ulin (HBIG) should be given, preferably within 24 hours. The effectiveness of HBIG given later than 7 days after HBV exposure is unknown. 8,10,40 If the source is HBsAg seropositive and the exposed person is known not to have responded to a threedose vaccine series, a single dose of HBIG and a dose of hepatitis B vaccine need to be given as soon as possible after the exposure with subse quent vaccine doses given at 1 month and 6 months after the initial dose. If the exposed per son is known not to have responded to a threedose vaccine series and to revaccination, two doses of HBIG need to be given, one dose as soon as possible after exposure and the second dose 1 month later.

# c. Hepatitis C
HCV is the etiologic agent in most cases of par enterally transmitted non-A, non-B hepatitis in the United States. 58,59 During the past decade, the annual number of newly acquired HCV infections has ranged from an estimated 180,000 in 1984 to an estimated 28,000 in 1995. Of these, an estimat ed 2% to 4% occurred among health care person nel who were occupationally exposed to blood. 59 A case-control study of patients with acute non-A, non-B hepatitis, conducted before the identification of HCV, showed a significant asso ciation between acquisition of disease and health care employment, specifically patient care or laboratory work. 60 Seroprevalence stud ies among hospital-based health care personnel have shown seroprevalence rates of antibody to HCV (anti-HCV) ranging from 1% to 2%.  In a study that assessed risk factors for infection in health care personnel, a history of accidental needlesticks was independently associated with anti-HCV seropositivity. 61 Several case reports have documented transmis sion of HCV infection from anti-HCV-seropositive patients to health care personnel as a result of accidental needlesticks or cuts with sharp instru ments. 65,66 In follow-up studies of health care per sonnel who sustained percutaneous exposures to blood from anti-HCV-seropositive patients, the rate of anti-HCV seroconversion averaged 1.8% (range 0% to 7%).  In a study in which HCV RNA polymerase chain reaction methods were used to measure HCV infection, the rate of HCV transmission was 10%. 70 The incubation period for hepatitis C is 6 to 7 weeks, and nearly all persons with acute infec-AJIC June 1998 tion will have chronic HCV infection occur with persistent viremia and the potential for trans mission of HCV to others.
Serologic assays to detect anti-HCV are com mercially available. The interpretation of anti-HCV test results is limited by several factors: (a) these assays will not detect anti-HCV in approxi mately 5% of persons infected with HCV; (b) these assays do not distinguish between acute, chronic, and past infection; (c) there may be a prolonged interval between the onset of acute illness with HCV and seroconversion; and (d) when the assays are used in populations with a low prevalence of HCV infection, commercial screening assays for anti-HCV yield a high proportion (as great as 50%) of false-positive results. 34,59 Although no true confirmatory test has been developed, supplemen tal tests for specificity are available and should be used to judge the validity of repeatedly reactive results by screening assays.
Although the value of immune globulin for postexposure prophylaxis after occupational exposure to HCV has been difficult to assess,  postexposure prophylaxis with immune globulin does not appear to be effective in preventing HCV infection. Current immune globulin preparations are manufactured from plasma that has been screened for HCV antibody; positive lots are excluded from use. An experimental study in chimpanzees found that administration 1 hour after exposure to HCV of immune globulin manu factured from anti-HCV-screened plasma did not prevent infection or disease. 74 Thus, available data do not support the use of immune globulin for postexposure prophylaxis against hepatitis C, and its use is not recommended. There is no informa tion regarding the use of antiviral agents, such as interferon alfa, in the postexposure setting, and such prophylaxis is not recommended. 37 Health care institutions should consider imple menting recommended policies and procedures for follow-up for HCV infection after percuta neous or mucosal exposures to blood. At a mini mum, such policies can include (1) baseline test ing of the source for anti-HCV, (2) baseline and follow-up testing (e.g., 6 months) for anti-HCV and alanine aminotransferase activity of the per son exposed to an anti-HCV seropositive source, (3) confirmation by supplemental anti-HCV test ing of all anti-HCV results reported as repeatedly active by enzyme immunoassay, (4) recommen dation against postexposure prophylaxis with immune globulin or antiviral agents (e.g., inter feron), and (5) education of health care personnel about the risk for and prevention of bloodborne infections, including HCV, in occupational set tings, with the information routinely updated to ensure accuracy. 37 Among health care personnel in the postexposure period, onset of HCV infec tion may be detected earlier by measuring HCV RNA with polymerase chain reaction rather than by measuring anti-HCV with enzyme immunoas say. However, polymerase chain reaction is not a licensed assay, and the accuracy of the results are highly variable. 37

# d. Human immunodeficiency virus
Nosocomial transmission of human immuno deficiency virus (HIV) infection from patients to health care personnel may occur after percuta neous or, infrequently, mucocutaneous exposure to blood or body fluids containing blood. According to prospective studies of health care personnel percutaneously exposed to HIV-infect ed blood, the average risk for HIV infection has been estimated to be 0.3%. 45, A retrospective case-control study to identify risk factors for HIV seroconversion among health care personnel after a percutaneous exposure to HIV-infected blood found that they were more likely to become infected if they were exposed to a larger quantity of blood, represented in the study as (1) presence of visible blood on the device before injury, (2) a procedure that involved a needle placed directly in the patient's vein or artery, or (3) deep injury. 45 Transmission of HIV infection also was associat ed with injuries in which the source patient was terminally ill with AIDS; this may be attributable to the increased titer of HIV in blood that is known to accompany late stages of illness or pos sibly to other factors, such as the presence of syn cytia-inducing strains of HIV in these patients. In addition, the findings of this study suggested that the postexposure use of zidovudine may be pro tective for health care personnel. 45 Factors that determine health care personnel's risk of infection with HIV include the prevalence of infection among patients, the risk of infection transmission after an exposure, and the fre quency and nature of exposures. 79 Most person nel who acquire infection after percutaneous exposure have HIV antibody develop within 6 months of exposure. HIV-infected persons are likely to transmit virus from the time of early infection throughout life.
In 1990, CDC published guidelines for postex posure management of occupational exposure to HIV, 33 and provisional recommendations for postexposure chemoprophylaxis were published CDC Personnel Health Guideline 305 in 1996. 80 In 1998, both of these documents were updated and consolidated to reflect current sci entific knowledge on the efficacy of postexpo sure prophylaxis and the use of antiretroviral therapies. 81 The U.S. Public Health Service will periodically review scientific information on antiretroviral therapies and publish updated recommendations for their use as postexposure prophylaxis as necessary.

# Conjunctivitis
Although conjunctivitis can be caused by a vari ety of bacteria and viruses, adenovirus has been the primary cause of nosocomial outbreaks of conjunctivitis. Nosocomial outbreaks of conjunc tivitis caused by other pathogens are rare.
Adenoviruses, which can cause respiratory, ocular, genitourinary, and gastrointestinal infections, are a major cause of epidemic kera toconjunctivitis in the community and health care settings. Nosocomial outbreaks have pri marily occurred in eye clinics or offices but have also been reported in neonatal intensive care units and long-term care facilities.  Patients and health care personnel have acquired and transmitted epidemic keratocon junctivitis during these outbreaks. The incuba tion period ranges from 5 to 12 days, and shed ding of virus occurs from late in the incubation period to as long as 14 days after onset of dis ease. 83 Adenovirus survives for long periods on environmental surfaces; ophthalmologic instru ments and equipment can become contaminat ed and transmit infection. Contaminated hands are also a major source of person-to-person transmission of adenovirus, both from patients to health care personnel and from health care personnel to patients. Handwashing, glove use, and disinfection of instruments can prevent the transmission of adenovirus. 82,83 Infected personnel should not provide patient care for the duration of symptoms after onset of epidemic keratoconjunctivitis 82,83 or purulent con junctivitis caused by other pathogens.

# Cytomegalovirus
There are two principal reservoirs of cytomegalovirus (CMV) in health care institu tions: (a) infants and young children infected with CMV and (b) immunocompromised patients, such as those undergoing solid-organ or bone-marrow transplantation or those with AIDS.  However, personnel who provide care to such high-risk patients have a rate of primary CMV infection that is no higher than that among personnel without such patient contact (3% vs 2%).  In areas where there are patient populations with a high prevalence of CMV, seroprevalence studies and epidemiologic investigations have also demon strated that personnel who care for patients have no greater risk of acquiring CMV than do person nel who have no patient contact. 92,100, In addition, epidemiologic studies that included DNA testing of viral strains have demonstrated that personnel who acquired CMV infections while providing care to CMV-infected infants had not acquired their infections from the CMV-infect ed patients. 88,92,96, CMV transmission appears to occur directly either through close, intimate contact with an excreter of CMV or through contact with contaminated secre tions or excretions, especially saliva or urine. 101, Transmission by the hands of personnel or infected persons has also been suggested. 92,115 The incubation period for person-to-person transmission is not known. Although CMV can survive on environmen tal surfaces and other objects for short periods, 116 there is no evidence that the environment plays a role in the transmission of infection. 92 Because infection with CMV during pregnancy may have adverse effects on the fetus, women of childbearing age need to be counseled regarding the risks and prevention of transmission of CMV in both nonoccupational and occupational set tings. 117 Although most fetal infections follow pri mary maternal infection, fetal infection may fol low maternal reinfection or reactivation. 118,119 There are no studies that clearly indicate that seronegative personnel may be protected from infection by transfer to areas with less contact with patients likely to be reservoirs for CMV infec tion. 88,92,102,105,106,119,120 Serologic or virologic screening programs to identify CMV-infected patients or seronegative female personnel of childbearing age are imprac tical and costly for the following reasons: (a) the virus can be intermittently shed, 121 and repeated screening tests may be needed to identify shed ders; (b) seropositivity for CMV does not offer complete protection against maternal reinfection or reactivation and subsequent fetal infec tion 118,119 ; and (c) no currently available vac cines  or prophylactic therapy 90, can pro vide protection against primary infection.
Work restrictions for personnel who contract CMV illnesses are not necessary. The risk of transmission of CMV can be reduced by careful adherence to handwashing and standard precautions. 3,119,130 AJIC June 1998

# Diphtheria
Nosocomial transmission of diphtheria among patients and personnel has been reported.  Diphtheria is currently a rare disease in the United States. During 1980 through 1994, only 41 diphthe ria cases were reported 134 ; however, community out breaks of diphtheria have occurred in the past, 135 and clusters of infection may occur in communities where diphtheria was previously endemic. 136 In addition, diphtheria epidemics have been occurring since 1990 in the new independent states of the for mer Soviet Union  and in Thailand. 140 At least 20 imported cases of diphtheria have been reported in countries in Europe, 139,141 and two cases occurred in U.S. citizens visiting or working in the Russian Federation and Ukraine. 142 Health care personnel are not at substantially higher risk than the general adult population for acquiring diphtheria; however, there is a potential for sporadic or imported cases to require medical care in the United States.
Diphtheria, caused by Corynebacterium diphthe riae, is transmitted by contact with respiratory droplets or contact with skin lesions of infected patients. The incubation period is usually 2 to 5 days. Patients with diphtheria are usually infec tious for 2 weeks or less, but communicability can persist for several months. 143 Droplet precautions are recommended for patients with pharyngeal symptoms, and contact precautions are recom mended for patients with cutaneous lesions. Precautions need to be maintained until antibiotic therapy is completed and results of two cultures taken at least 24 hours apart are negative. 3 Limited serosurveys conducted since 1977 in the United States indicate that 22% to 62% of adults 18 to 39 years old may lack protective diphtheria antibody levels.  Prevention of diphtheria is best accomplished by maintaining high levels of diphtheria immunity among children and adults. 19,137,138 Immunization with tetanus and diphtheria toxoid (Td) is recommended every 10 years for all adults who have completed the pri mary immunization series (Table 1). 9,19 Health care personnel need to consider obtaining Td immu nization from their health care providers. 9 To determine whether health care personnel directly exposed to oral secretions of patients infected with toxigenic strains of C. diphtheriae are carriers, cultures of the nasopharynx may be obtained. Exposed personnel need to be evaluated for evidence of disease daily for 1 week. 149 Although the efficacy of antimicrobial prophylaxis in pre venting secondary disease has not been proved, prophylaxis with either a single intramuscular CDC Personnel Health Guideline 307 injection of benzathine penicillin (1.2 mouse units) or oral erythromycin (1 gm/day) for 7 days has been recommended. 19 Follow-up nasopharyngeal cultures for C. diphtheriae need to be obtained at least 2 weeks after antimicrobial therapy is com pleted. If the organism has not been eradicated, a 10-day course of erythromycin needs to be given. 149 In addition, previously immunized exposed per sonnel need to receive a dose of Td if they have not been vaccinated within the previous 5 years. 19 Exclusion from duty is indicated for personnel with C. diphtheriae infection or those determined to be asymptomatic carriers until antimicrobial ther apy is completed and nasopharyngeal culture results are negative.

# Gastrointestinal infections, acute
Gastrointestinal infections may be caused by a variety of agents, including bacteria, viruses, and protozoa. However, only a few agents have been documented in nosocomial transmission (Table 5).  Nosocomial transmission of agents that cause gastrointestinal infections usually results from contact with infected individuals, 150,161,163,169 from consumption of contaminated food, water, or other beverages, 150,166,169,170 or from exposure to contaminated objects or environmental sur faces. 152,153,171 Airborne transmission of small round-structured viruses (Norwalk-like viruses) has been postulated but not proved. 164,165, Inadequate handwashing by health care person nel 176 and inadequate sterilization or disinfection of patient-care equipment and environmental sur faces increase the likelihood of transmission of agents that cause gastrointestinal infections. Generally, adherence to good personal hygiene by personnel before and after all contacts with patients or food and to either standard or contact precautions 3 will minimize the risk of transmit ting enteric pathogens. 167,177 Laboratory personnel who handle infectious materials also may be at risk for occupational acquisition of gastrointestinal infections, most commonly with Salmonella typhi. Although the incidence of laboratory-acquired S. typhi infec tion has decreased substantially since 1955, infections continue to occur among laboratory workers, particularly those performing profi ciency exercises or research tests. 151,162 Several typhoid vaccines are available for use in labo ratory workers who regularly work with cul tures or clinical materials containing S. typhi. 178 The oral live-attenuated Ty21a vaccine, the intramuscular Vi capsular polysaccharide vaccine, or the subcutaneous inactivated vac cine may be given (Table 1). 178 Booster doses of vaccine are required at 2-to 5-year intervals, depending on the preparation used. The liveattenuated Ty21a vaccine should not be used for immunocompromised persons, including those known to be infected with HIV. 178 Personnel who acquire an acute gastroin testinal illness (defined as vomiting, diarrhea, or both, with or without associated symptoms such as fever, nausea, and abdominal pain) are likely to have high concentrations of the infect ing agent in their feces (bacteria, viruses, and parasites) or vomitus (viruses and para sites). 165,179,180 It is important to determine the etiology of gastrointestinal illness in health care personnel who care for patients at high risk for severe disease (e.g., neonates, elderly persons, and immunocompromised patients). The initial evaluation of personnel with gas troenteritis needs to include a thorough history and determination of the need for specific lab oratory tests, such as stool or blood cultures, staining procedures, and serologic or antigenantibody tests. 162,171,181,182 After resolution of some acute bacterial gas trointestinal illnesses, some personnel may have persistent carriage of the infectious agent. Once the person has clinically recovered and is having formed stools, however, the risk of trans mission of enteric pathogens is minimized by adherence to standard precautions. 3,167 In addi tion, appropriate antimicrobial therapy may eradicate fecal carriage of Shigella 183 or Campylobacter. 184 In contrast, antimicrobial or antiparasitic therapy may not eliminate car riage of Salmonella 185 or Cryptosporidium. Moreover, antimicrobials may prolong excre tion of Salmonella 186 and lead to emergence of resistant strains. 187 However, transmission of Salmonella to patients from personnel who are asymptomatic carriers of Salmonella has not been well documented. 167 In general, antimicro bial therapy is not recommended, unless the person is at high risk for severe disease. 188 When antibiotics are given, stool cultures AJIC June 1998 should be obtained at least 48 hours after com pletion of antibiotic therapy.
Restriction from patient care and the patient's environment or from food handling is indicated for personnel with diarrhea or acute gastrointestinal symptoms, regardless of the causative agent. 3,171 Some local and state agen cies have regulations that require work exclu sion for health care personnel, food handlers, or both who have gastrointestinal infections caused by Salmonella or Shigella. These regula tions may require such personnel to be restrict ed from duty until results of at least two con secutive stool cultures obtained at least 24 hours apart are negative.

# Hepatitis A
Nosocomial hepatitis A occurs infrequently, and transmission to personnel usually occurs when the source patient has unrecognized hepatitis and is fecally incontinent or has diarrhea.  Other risk factors for hepatitis A virus (HAV) transmission to personnel include activities that increase the risk of fecal-oral contamination such as (a) eating or drinking in patient care areas, 189,191,193,199 (b) not washing hands after handling an infected infant, 191,199,200 and (c) sharing food, beverages, or cigarettes with patients, their families, or other staff members. 189,191 HAV is transmitted primarily by the fecal-oral route. It has not been reported to occur after inadvertent needlesticks or other contact with blood, but it has rarely been reported to be transmitted by transfusion of blood prod ucts. 193,201,202 The incubation period for HAV is 15 to 50 days. Fecal excretion of HAV is greatest during the incubation period of disease before the onset of jaundice. 203 Once disease is clini cally obvious, the risk of transmitting infection is decreased. However, some patients admitted to the hospital with HAV, particularly immuno compromised patients, may still be shedding virus because of prolonged or relapsing disease, and such patients are potentially infective. 190,203 Fecal shedding of HAV, formerly believed to continue only as long as 2 weeks after onset of dark urine, 203 has been shown to occur as late as 6 months after diagnosis of infection in prema ture infants. 189 Anicteric infection is typical in young children and infants. 204 Personnel can protect themselves and others from infection with HAV by adhering to stan dard precautions. 3 Food-borne transmission of hepatitis A is not discussed in this guideline, but it has occurred in health care settings. 205,206 Two inactivated hepatitis A vaccines are now available and provide long-term preexposure protection against clinical infection with greater than 94% efficacy. 204 Serologic surveys among health care personnel have not shown greater prevalence of HAV infection than in control populations 52,192,207,208 ; therefore, routine administration of vaccine in health care person nel is not recommended. Vaccine may be useful for personnel working or living in areas where HAV is highly endemic and is indicated for per sonnel who handle HAV-infected primates or are exposed to HAV in a research laboratory. The role of hepatitis A vaccine in controlling outbreaks has not been adequately investigat ed. 9 Immune globulin given within 2 weeks after an HAV exposure is more than 85% effec tive in preventing HAV infection 204 and may be advisable in some outbreak situations. 9,204 Restriction from patient care areas or food handling is indicated for personnel with HAV infection. They may return to regular duties 1 week after onset of illness. 9

# Herpes simplex
Nosocomial transmission of herpes simplex virus (HSV) is rare. Nosocomial transmission has been reported in nurseries  and intensive care units 212,213 where high-risk patients (e.g., neonates, patients with severe malnutrition, patients with severe burns or eczema, and immunocompromised patients) are located. Nosocomial transmission of HSV occurs primarily through contact either with primary or recurrent lesions or with virus-contain ing secretions, such as saliva, vaginal secretions, or amniotic fluid. 210,212,214 Exposed areas of skin are the most likely sites of nosocomial infection, par ticularly when minor cuts, abrasions, or other skin lesions are present. 213 The incubation period of HSV is 2 to 14 days. 215 The duration of viral shed ding has not been well defined. 216 Personnel may acquire a herpetic infection of the fingers (herpetic whitlow or paronychia) from exposure to contaminated oral secretions. 213,214 Such exposures are a distinct hazard for nurses, anesthesiologists, dentists, respiratory care per sonnel, and other personnel who have direct (usu ally hand) contact with either oral lesions or res piratory secretions from patients. 213 Less fre quently, personnel may acquire mucocutaneous infection on other body sites from contact with infectious body secretions. 217

# CDC Personnel Health Guideline 309
Personnel with active infection of the hands (her petic whitlow) can potentially transmit HSV infec tion to patients with whom they have contact. 214 Transmission of HSV from personnel with orofa cial HSV infection to patients has also been infre quently documented 209 ; however, the magnitude of this risk is unknown. 211,218 Although asymptomatic infected persons can shed the virus, they are less infectious than persons with active lesions. 216,219 Personnel can protect themselves from acquiring HSV by adhering to standard precau tions. 3 The risk of transmission of HSV from personnel with orofacial infections to patients can be reduced by handwashing before all patient care and by the use of appropriate bar riers, such as a mask or gauze dressing, to pre vent hand contact with the lesion.
Because personnel with orofacial lesions may touch their lesions and potentially transmit infec tions, they should be evaluated to determine their potential for transmitting herpes simplex to patients at high risk for serious disease (e.g., neonates, patients with severe malnutrition, patients with severe burns or eczema, and immunocompromised patients) and excluded from the care of such patients as indicated. The evaluation should consider the extent of the lesion and the severity of illness in the patient population that personnel will contact. Personnel with HSV infections of the fingers or hands can more easily transmit infection and therefore need to be excluded from patient care until their lesions have crusted. In addition, herpetic lesions may be secondarily infected by Staphylococcus and Streptococcus, and personnel with such infections should be evaluated to determine whether they need to be excluded from patient contact until the secondary infection has resolved. There have been no reports that person nel with genital HSV infections have transmitted HSV to patients; therefore, work restrictions for personnel with genital herpes are not indicated.

# Measles
Nosocomial transmission of measles virus (sporadic and epidemic) has been well described.  From 1985 through 1991, approx imately 3000 (4%) of all reported episodes of measles in the United States were probably acquired in a medical facility; of these, more than 700 (25%) occurred in health care personnel, many of whom were not vaccinated. 9 Data have suggested that health care personnel have a risk of measles 13-fold that of the general population. 9 Of the 2765 episodes of measles reported during 1992 through 1995, 385 (13.9%) occurred in health care settings. 221,230 Measles is transmitted both by large droplets during close contact between infected and sus ceptible persons and by the airborne route. 229,231 Measles is highly transmissible and frequently misdiagnosed during the prodromal stage. The incubation period for measles is 5 to 21 days. Immunocompetent persons with measles shed the virus from the nasopharynx, beginning with the prodrome until 3 to 4 days after rash onset; immunocompromised persons with measles may shed virus for extended periods. 232 Strategies to prevent nosocomial transmis sion of measles include (a) documentation of measles immunity in health care personnel, (b) prompt identification and isolation of persons with fever and rash, and (c) adherence to air borne precautions for suspected and proven cases of measles. 3 It is essential that all personnel have docu mentation of measles immunity, regardless of their length of employment or whether they are involved in patient care. Further, some states have regulations requiring measles immunity for health care personnel. Although persons born before 1957 are generally considered to be immune to measles, serologic studies indicate that 5% to 9% of health care personnel born immune. 9,233,234 before 1957 may not be Furthermore, during 1985 through 1989, 29% of all measles cases in U.S. health care person nel occurred in those born before 1957. 221 Consideration should be given to recommend ing a dose of measles-mumps-rubella trivalent vaccine (MMR) to personnel born before 1957 who are unvaccinated and who lack (a) a histo ry of previous measles disease, (b) documenta tion of receipt of one dose of live-measles vac cine, and (c) serologic evidence of measles immunity. 9 Health care personnel born during or after 1957 should be considered immune to measles when they have (a) documentation of physician-diagnosed measles, (b) documenta tion of two doses of live measles vaccine on or after their first birthday, or (c) serologic evi dence of measles immunity (persons with an "indeterminate" level of immunity on testing should be considered susceptible). Persons born between 1957 and 1984 who received childhood measles immunization were given only one dose of vaccine during infancy and may require a second dose of vaccine. 8

# AJIC

# June 1998
Serologic screening for measles immunity is not necessary before administration of measles vaccine, unless the medical facility considers it cost-effective or the person to be vaccinated requests it.  When serologic screening before vaccination is done, tracking systems are needed to ensure that those identified as susceptible are subsequently vaccinated in a timely manner. 237 During measles outbreaks, serologic screening before vaccination is not necessary. In outbreak situations, prompt administration of vaccine is necessary to halt disease transmission.
Work restrictions are necessary for personnel who acquire measles; they need to be excluded from duty for 7 days after the rash appears. Likewise, personnel not immune to measles need to be excluded from duty from 5 days after the first exposure to 21 days after the last exposure to measles.

# Meningococcal disease
Community-acquired meningococcal disease is typically caused by a variety of serogroups of Neisseria meningitidis; serogroups B and C cause 46% and 45% of the endemic cases, respectively. Serogroups A, Y, and W-135 account for nearly all the remaining endemic cases. 15 In contrast, epidem ic meningococcal disease has, since the early 1990s, been caused increasingly by serogroup C. 15,239,240 Nosocomial transmission of N. meningitidis is uncommon. In rare instances, when proper pre cautions were not used, N. meningitidis has been transmitted from patient to personnel, through contact with the respiratory secretions of patients with meningococcemia or meningo coccal meningitis,  or through handling laboratory specimens. 241 Lower respiratory tract infections caused by N. meningitidis may present a greater risk of transmission than either meningococcemia or meningitis, 243,244 especially if the patient has an active, produc tive cough. 244 The risk of personnel acquisition of meningococcal disease from casual contact (e.g., cleaning rooms or delivering food trays) appears to be negligible. 244 N. meningitidis infection is probably transmit ted by large droplets; the incubation period is from 2 to 10 days, and patients infected with N. meningitidis are rendered noninfectious by 24 hours of effective therapy. Personnel who care for patients with suspected N. meningitidis infection can decrease their risk of infection by adhering to droplet precautions. 3 Postexposure prophylaxis is advised for persons who have had intensive, unprotected contact (i.e., without wearing a mask) with infected patients (e.g., mouth-to-mouth resuscitation, endotracheal intubation, endotracheal tube management, or close examination of the oropharynx of patients). 15 Antimicrobial prophylaxis can eradi cate carriage of N. meningitidis and prevent infec tions in personnel who have unprotected exposure to patients with meningococcal infections. 245,246 Because secondary cases of N. meningitidis occur rapidly (within the first week) after expo sure to persons with meningococcal disease, 247 it is important to begin prophylactic therapy immediately after an intensive, unprotected exposure, often before results of antimicrobial testing are available. Prophylaxis administered later than 14 days after exposure is probably of limited or no value. 15 Rifampin (600 mg orally every 12 hours for 2 days) is effective in eradi cating nasopharyngeal carriage of N. meningi tidis. 245 Ciprofloxacin (500 mg orally) and ceftri axone (250 mg intramuscularly) in single-dose regimens are also effective in reducing nasopha ryngeal carriage of N. meningitidis and are rea sonable alternatives to the multidose rifampin regimen. 15,246 These antimicrobials may be useful when infections are caused by rifampin-resistant meningococci or rifampin is contraindicated. Rifampin and ciprofloxacin are not recommend ed for pregnant women. 15,106,248,249 The quadrivalent A,C,Y,W-135 polysaccharide vaccine has been used successfully to control community outbreaks caused by serogroup C, 15,239,240,248 but its use is not recommended for postexposure prophylaxis in health care settings. 15 However, preexposure vaccination may be consid ered for laboratory personnel who routinely han 15,241 dle soluble preparations of N. meningitidis.
Healthy persons may have nasopharyngeal car riage of N. meningitidis. 245, Nosocomial trans mission from carriers to personnel has not been reported. In the absence of exposures to patients with N. meningitidis infection, personnel who are asymptomatic carriers need not be identified, treated, or removed from patient care activities. However, personnel with meningococcal infection need to be excluded from duty until 24 hours after the start of effective therapy.

# Mumps
Mumps transmission has occurred in hospi tals and long-term care facilities housing adoles cents and young adults. 253,254 Most cases of CDC Personnel Health Guideline 311 mumps in health care personnel have been com munity acquired.
Mumps is transmitted by contact with viruscontaining respiratory secretions, including sali va; the portals of entry are the nose and mouth. The incubation period varies from 12 to 25 days and is usually 16 to 18 days. The virus may be pre sent in saliva for 6 to 7 days before parotitis and may persist for as long as 9 days after onset of dis ease. Exposed personnel may be infectious for 12 to 25 days after their exposure, and many infected persons remain asymptomatic. 255 Droplet precau tions are recommended for patients with mumps; such precautions should be continued for 9 days after the onset of parotitis. 3 An effective vaccination program is the best approach to prevention of nosocomial mumps transmission. 12 Vaccination with mumps virus vac cine is recommended, unless otherwise con traindicated, for all those who are susceptible to mumps; 12,256 combined MMR is the vaccine of choice, 257 especially when the recipient also is like ly to be susceptible to measles, rubella, or both.
Personnel should be considered immune to mumps if they have (a) documentation of physi cian-diagnosed mumps, (b) documentation of receipt of one dose of live mumps vaccine on or after their first birthday, or (c) serologic evidence of immunity (individuals who have an "indeter minate" antibody level should be considered sus ceptible). 12 Most persons born before 1957 are likely to have been infected naturally and may be considered to be immune, even though they may not have had clinically recognized mumps. Outbreaks among highly vaccinated populations have occurred and have been attributed to pri mary vaccine failure. 258 Work restrictions are necessary for personnel who acquire mumps; such restrictions should be imposed for 9 days after the onset of parotitis. Likewise, susceptible personnel who are exposed to mumps need to be excluded from duty from the 12th day after the first exposure until the 26th day after the last exposure. 9,255

# Parvovirus
Human parvovirus B19 (B19) is the cause of erythema infectiosum (fifth disease), a common rash illness that is usually acquired in childhood. Immunocompetent persons infected with B19 may have an acute, self-limited arthropathy, with or without a rash or anemia of short duration. However, patients with preexisting anemia (e.g., patients with sickle-cell anemia or thalassemia) may have aplastic crisis occur. Immunodeficient patients (e.g., patients with leukemia or AIDS) may become chronically infected with B19 and have chronic anemia. 259,260 Transmission of B19 to health care personnel from infected patients appears to be rare but has been reported.  In two investigations of health care personnel exposures to B19, the rate of infec tion among exposed nurses was not higher than the rate among unexposed control subjects. 266,267 In another investigation of health care personnel exposed to a patient with undetected chronic B19 infection, none of the susceptible employees became infected. 268 Personnel have acquired infection while working in laboratories or during the care of patients with B19-associated sickle-cell aplastic crises.  B19 may be transmitted through contact with infected persons, fomites, or large droplets. 266,272,273 The incubation period is variable, depending on the clinical manifestation of disease, and ranges from 6 to 10 days. 260 The period of infectivity also varies, depending on the clinical presentation or stage of disease. Persons with erythema infectio sum are infectious before the appearance of the rash, those with infection and aplastic crises for as long as 7 days after onset of illness, and persons with chronic infection for years.
Pregnant personnel are at no greater risk of acquiring B19 infection than are nonpregnant per sonnel; however, if a pregnant woman does acquire B19 infection during the first half of pregnancy, the risk of fetal death (fetal hydrops, spontaneous abor tion, and stillbirth) is increased. 274,275 Because of the serious nature of the consequences for the fetus, female personnel of childbearing age need to be counseled regarding the risk of transmission of B19 and appropriate infection control precautions. 3 Isolation precautions are not indicated for most patients with erythema infectiosum because they are past their period of infectiousness at the time of clinical illness. 271,274 However, patients in aplas tic crisis from B19 or patients with chronic B19 infection may transmit the virus to susceptible health care personnel or other patients; therefore, patients with preexisting anemia who are admit ted to the hospital with febrile illness and tran sient aplastic crises should remain on droplet pre cautions for 7 days and patients with known or suspected chronic infection with B19 should be placed on droplet precautions on admission and for the duration of hospitalization. 3,263 Work restrictions are not necessary for personnel exposed to B19.
AJIC June 1998

# Pertussis
Nosocomial transmission of Bordetella pertus sis has involved both patients and personnel; nonimmunized children are at greatest risk.  Serologic studies of health care personnel indi cate that personnel may be exposed to and infected with pertussis much more frequently than indicated by the occurrence of recognized clinical illness. 277,279,281,282 In one such study, the level of pertussis agglutination antibodies was found to correlate with the degree of patient con tact; the prevalence of such antibody was highest in pediatric house staff (82%) and ward nurses (71%) and lowest in nurses with administrative responsibilities (35%). 277 Pertussis is highly contagious; secondary attack rates exceed 80% in susceptible household con tacts.  B. pertussis transmission occurs by con tact with respiratory secretions or large aerosol droplets from the respiratory tracts of infected per sons. The incubation period is usually 7 to 10 days. The period of communicability starts at the onset of the catarrhal stage and extends into the paroxysmal stage up to 3 weeks after onset of symptoms. Prevention of secondary transmission of pertussis is especially difficult during the early stages of the dis ease because pertussis is highly communicable in the catarrhal stage, when the symptoms are non specific and the diagnosis is uncertain.
During nosocomial pertussis outbreaks, the risk of acquiring infection among patients or personnel is often difficult to quantify because exposure is not easily determined. Furthermore, clinical symptoms in adults are less severe than in children and may not be recognized as pertussis. Pertussis should be considered for any person seeking treatment with an acute cough lasting at least 7 days, particularly if accompanied by paroxysms of coughing, inspira tory whoop, or posttussive vomiting. 280,281 Prevention of transmission of B. pertussis in health care settings involves (a) early diagnosis and treatment of patients with clinical infection, (b) implementation of droplet precautions for infectious patients, 3 (c) exclusion of infectious personnel from work, and (d) administration of postexposure prophylaxis to persons exposed to infectious patients. 279 Patients with suspected or confirmed pertussis who are admitted to the hos pital need to be placed on droplet precautions until they have clinical improvement and have received antimicrobial therapy for at least 5 days.
Vaccination of adolescents and adults with whole-cell B. pertussis vaccine is not recommend ed 19 because local and systemic reactions have been observed more frequently in these groups than in children. Acellular pertussis vaccine is immunogenic in adults and carries a lower risk of adverse events than does whole-cell vaccine. 280,286 However, the acellular vaccine has not been licensed for use in persons 7 years old or older. Because immunity among vaccine recipients wanes 5 to 10 years after the last vaccine dose (usually given at 4 to 6 years of age), personnel may play an important role in transmitting pertus sis to susceptible infants. However, additional studies are needed to assess whether booster doses of acellular vaccines are indicated for adults.
Postexposure prophylaxis is indicated for person nel exposed to pertussis; a 14-day course of either erythromycin (500 mg orally four times daily) or trimethoprim-sulfamethoxazole (one tablet twice daily) has been used for this purpose. The efficacy of such prophylaxis has not been well documented, but studies suggest that it may minimize transmis sion. 19,279,287,288 There are no data on the efficacy of newer macrolides (clarithromycin or azithromycin) for prophylaxis in persons exposed to pertussis.
Restriction from duty is indicated for personnel with pertussis from the beginning of the catarrhal stage through the third week after onset of parox ysms, or until 5 days after the start of effective antimicrobial therapy. Exposed personnel do not need to be excluded from duty.

# Poliomyelitis
The last cases of indigenously acquired wildvirus poliomyelitis occurred in the United States in 1979. 289 Since then, all cases of endemic poliomyelitis reported in the United States (5 to 10 endemic cases/year) have been related to the administration of oral polio vaccine (OPV). 21 Although the risk of transmission of poliovirus in the United States is very low, wild poliovirus may potentially be introduced into susceptible popula tions with low immunization levels.
Poliovirus is transmitted through contact with feces or urine of infected persons but can be spread by contact with respiratory secretions and, in rare instances, through items contami nated with feces. The incubation period for nonparalytic poliomyelitis is 3 to 6 days, but is usu ally 7 to 21 days for paralytic polio. 290 Com municability is greatest immediately before and after the onset of symptoms, when the virus is in the throat and excreted in high concentration in feces. The virus can be recovered from the throat for 1 week and from feces for several weeks to months after onset of symptoms.

# CDC Personnel Health Guideline 313
Vaccine-associated poliomyelitis may occur in the recipient (7 to 21 days after vaccine administration) or susceptible contacts of the vaccine recipient (20 to 29 days after vaccine administration). 289 Adults have a slightly increased risk of vaccine-associated para lytic poliomyelitis after receipt of OPV; therefore, inactivated poliovirus vaccine (IPV) should be used when adult immunization is warranted. 8,16,21 Also, because immunocompromised persons may be at greater risk for development of poliomyelitis after exposure to vaccine virus, IPV rather than OPV is rec ommended when vaccinating pregnant or immuno compromised personnel, or personnel who may have contact with immunocompromised patients. 8,16,21,290 Health care personnel who may have contact with patients excreting wild virus (e.g., imported poliomyelitis case) and laboratory personnel han dling specimens containing poliovirus or per forming cultures to amplify virus should receive a complete series of polio vaccine; if previously vac cinated, they may require a booster dose of either IPV or OPV. 8,21 For situations where immediate protection is necessary (e.g., an imported case of wild-virus poliomyelitis requiring care), addition al doses of OPV should be given to adults who have previously completed a polio vaccine series. 21

# Rabies
Human rabies cases occur primarily from exposure to rabid animals. Cases of human rabies have increased in the United States during the 1990s. 291 Laboratory and animal care personnel who are exposed to infected animals, their tis sues, and their excretions are at risk for the dis ease. Also, rabies transmission to laboratory per sonnel has been reported in vaccine production and research facilities after exposure to high titered infectious aerosols. 292,293 Theoretically, rabies may be transmitted to health care person nel from exposures (bite and nonbite) to saliva from infected patients, but no cases have been documented after these types of exposures. 294 It is also possible for rabies to be transmitted when other potentially infectious material (such as brain tissue) comes into contact with nonintact skin or mucous membranes. 22,294 Bites that pene trate the skin, especially bites to the face and hands, pose the greatest risk of transmission of rabies virus from animals to human beings. 22 The incubation period for rabies is usually 1 to 3 months, but longer periods have been reported. 295 Exposures to rabies can be minimized by adher ing to standard precautions when caring for per sons with suspected or confirmed rabies 3 and by using proper biosafety precautions in laborato ries. 5 Preexposure vaccination has been recom mended for all personnel who (a) work with rabies virus or infected animals or (b) engage in diagnostic, production, or research activities with rabies virus. 5,22 Consideration also may be given to providing preexposure vaccination to animal han dlers when research animals are obtained from the wild, rather than from a known supplier that breeds the animals.
Postexposure prophylaxis has been adminis tered to health care personnel after exposures to patients with rabies (Table 1),  but decisions regarding postexposure prophylaxis should be made on a case-by-case basis after discussion with public health authorities. 22

# Rubella
Nosocomial transmission of rubella has occurred from both male and female personnel to other susceptible personnel and patients, as well as from patients to susceptible personnel and other patients.  Rubella is transmitted by contact with nasopha ryngeal droplets from infected persons. The incu bation period is variable but may range from 12 to 23 days; most persons have the rash 14 to 16 days after exposure. The disease is most contagious when the rash is erupting, but virus may be shed from 1 week before to 5 to 7 days after the onset of the rash. 306 Rubella in adults is usually a mild disease, lasting only a few days; 30% to 50% of cases may be subclinical or inapparent.
Droplet precautions are used to prevent trans mission of rubella. Infants with congenital rubella may excrete virus for months to years; when caring for such patients, it is therefore advisable to use contact precautions for the first year of life, unless nasopharyngeal and urine culture results are nega tive for rubella virus after 3 months of age. 3 Ensuring immunity among all health care per sonnel (male and female) is the most effective way to eliminate nosocomial transmission of rubella. 8,9,14,256,307 Persons should be considered susceptible to rubella if they lack (a) documenta tion of one dose of live rubella vaccine on or after their first birthday and (b) laboratory evi dence of immunity (persons with indeterminate levels are considered susceptible). A history of previous rubella infection is unreliable and should not be considered indicative of immunity to rubella. Although birth before 1957 is general ly considered acceptable evidence of rubella immunity, a dose of MMR has been recommend-June 1998 ed for those health care personnel that do not have laboratory evidence of immunity. 9 In addi tion, birth before 1957 is not considered accept able evidence of rubella immunity for women of childbearing age; history of vaccination or labo ratory evidence of rubella immunity is particu larly important for women who may become pregnant. 9 Voluntary immunization programs are usually inadequate to ensure personnel pro tection. 7,308 Because many health departments mandate rubella immunity for health care per sonnel, personnel health programs should con sult with their local or state health departments before establishing policies for their facilities.
Serologic screening of personnel for immunity to rubella need not be done before vaccinating against rubella, unless the medical facility consid ers it cost-effective or the person getting vaccinat ed requests it. 7, When serologic screening before vaccination is done, tracking systems are needed to ensure that those identified as suscepti ble are subsequently vaccinated in a timely man ner. 237 Likewise, during rubella outbreaks, sero logic screening is not necessary. Pregnant women who are already immune to rubella are not at increased risk for adverse advents. 309 However, for theoretic reasons, a risk to the fetus from admin istration of live-virus vaccines cannot be excluded. Women should be counseled to avoid pregnancy for 30 days after administration of MMR or other rubella-containing vaccines. Routine precautions for vaccinating postpubertal women include (a) asking whether they are or may be pregnant, (b) not vaccinating those who say they are or may be pregnant, and (c) vaccinating those who state they are not pregnant after the potential risk to the fetus has been explained. If a pregnant woman is vaccinated or a woman becomes pregnant within 3 months after vaccination, she should be coun seled about the theoretic basis of concern for the fetus, but MMR vaccination during pregnancy should not ordinarily be a reason to consider ter mination of pregnancy. Rubella-susceptible women who are not vaccinated because of preg nancy should be counseled about the importance of being vaccinated as soon as they are no longer pregnant. 9 MMR is the vaccine of choice for rubel la, especially when the recipient also is likely to be susceptible to measles, mumps, or both (Table 2).
Work restrictions are necessary for personnel who acquire rubella; ill personnel need to be excluded from duty for 5 days after the rash appears. Likewise, personnel susceptible to rubel la require exclusion from duty from the seventh day after the first exposure through the 21st day after the last exposure (Table 3).

# Scabies and pediculosis a. Scabies
Scabies is caused by infestation with the mite Sarcoptes scabiei. The conventional (typical) clini cal presentation of scabies includes intense pruri tus and cutaneous tracks, where mites have bur rowed into the skin. Crusted or "Norwegian" sca bies may develop among immunocompromised and elderly individuals in which their skin may become hyperkeratotic; pruritus may not be pre sent, which also makes diagnosis difficult. In con ventional scabies, 10 to 15 mites are present, whereas in crusted scabies, thousands of mites are harbored in the skin, increasing the potential for transmission. 310,311 Nosocomial outbreaks of scabies have occurred in a variety of health care settings, including intensive care units, 312 rehabilitation centers, 313 long-term care facilities, 314,315 hospital wards, 316 a dialysis unit, 317 and a health care laundry. 318 In recent years there has been an increase in the occurrence of crusted scabies among immunocompromised patients, particu larly persons with HIV, which has led to the transmission of scabies among personnel, patients, and their families. 310, Nosocomial transmission of scabies occurs primarily through prolonged skin-to-skin con tact with an infested person who has conven tional scabies. 310,322 Shorter periods of skin-to skin contact with persons who have crusted sca bies may result in transmission of scabies. 323 Personnel have acquired scabies while perform ing patient care duties such as sponge bathing, lifting, or applying body lotions. 310,311,319,324 Transmission by casual contact, such as by hold ing hands, or through inanimate objects, such as infested bedding, clothes, or other fomites, has been reported infrequently. 317,318 The use of contact precautions when taking care of infested patients before application of scabicides can decrease the risk of transmission to personnel. 3,311 Routine cleaning of the environ ment of patients with typical scabies, especially bed linens and upholstered furniture, will aid in eliminating the mites. Additional environmental cleaning procedures may be warranted for crust ed scabies. 310,311, Recommendations for treatment and control of scabies in health care institutions have been published previously. 310,311, The recommend-
CDC Personnel Health Guideline 315
ed topical scabicides include permethrin cream (5%), crotamiton (10%), and lindane (1%) lotion; resistance to and adverse effects from lindane have been reported. 329 Single-dose oral iver mectin has recently been shown to be an effec tive therapy for scabies 323,330,332 but has not received Food and Drug Administration (FDA) approval for this purpose.
Most infested health care workers have typical scabies with low mite loads 333 ; a single correct application of a scabicide is adequate and imme diately decreases the risk of transmis sion. 25,319,322,324,334 There are no controlled evaluations of the efficacy of prophylactic scabi cide therapy among health care personnel, and some experts recommend two applications of scabicide for all infested personnel. 311,315,321 If personnel continue to have symptoms after ini tial treatment, another application of scabicide may be needed. Persistent symptoms likely rep resent newly hatched mites rather than new infestation; however, pruritus after scabies infes tation and treatment may persist for as long as 2 weeks, even without infestation. 25 Patients with crusted scabies may require repeated treatments and should be observed for recurrence of the mite infestation. 310,311,314,326 Personnel who are exposed to scabies but lack signs of infestation do not usually require prophylactic treatment with scabicides. In outbreak situations where transmission continues to occur, prophylaxis may be warranted for both patients and exposed health care personnel. 311,313 Restrictions from patient care are indicated for personnel infested with scabies until after they receive initial treatment and have been medically evaluated and determined to be free of infestation. They should be advised to report for further eval uation if symptoms do not subside.

# b. Pediculosis
Pediculosis is caused by infestation with any of three species of lice: Pediculus humanus capitus (human head louse), Pediculus humanus corporis (human body louse), and Phthirus pubis (pubic or crab louse).
Head lice are transmitted by head-to-head con tact or by contact with infested fomites such as hats, combs, or brushes. Nosocomial transmis sion, although not common, has occurred. 310 Body lice are usually associated with poor hygiene and overcrowded conditions. Trans mission occurs by contact with the skin or cloth ing of an infested person. Nosocomial transmis sion is unlikely.
Pubic lice are primarily found in the pubic hair but can be found in the axilla, eyelashes, or eyebrows. Transmission occurs primarily through intimate physical or sexual contact. Transmission by fomites, such as toilet seats or bedding, is uncommon. Nosocomial transmis sion is very unlikely.
Recommendations for control of pediculosis have been published previously. 310,327,335 The drugs recommended for treatment include permethrin cream 1%, pyrethrins with piperonyl butoxide, 1%. 328-330,335 malathion 0.5%, and lindane Resistance to various drugs has been reported. Local health departments may have information about drugs that are effective in their areas. Health care personnel exposed to patients with pediculosis do not require treatment, unless they show evidence of infestation.
Restriction from patient care is indicated for personnel with pediculosis until after they receive initial treatment and are found to be free of adult and immature lice. If symptoms do not subside after initial treatment, they should be advised to report for further evaluation.

# Staphylococcus aureus infection and carriage
Staphylococcal infection and carriage occur fre quently in human beings. In hospitals, the most important sources of S. aureus are infected and colonized patients. Previously, methicillin-suscep tible (but penicillin-resistant) S. aureus accounted for most staphylococcal infections. In recent years, however, methicillin-resistant S. aureus has accounted for approximately 80% of all S. aureus isolates reported to the National Nosocomial Infections Surveillance System. 336,337 The epidemi ology of methicillin-resistant S. aureus does not appear to differ from that of methicillin-suscepti ble, penicillin-resistant S. aureus, except that out breaks of methicillin-resistant S. aureus tend to occur more frequently among elderly or immuno compromised patients or among patients with severe underlying conditions. 338,339 Nosocomial transmission of S. aureus occurs primarily by the hands of personnel, which can become contaminated by contact with the colo nized or infected body sites of patients. 339,340 Hospital personnel who are infected or colonized with S. aureus also can serve as reservoirs and dis seminators of S. aureus,  and infected dietary personnel have been implicated in staphylococcal food poisoning. 345 The role of contaminated envi ronmental surfaces in transmission of S. aureus AJIC June 1998 has rarely been well documented 346 and remains controversial, although heavy contamination of fomites may facilitate transmission to patients by hands of personnel. 339 The incubation period for S. aureus infections varies by type of disease. For food-borne illness it is 30 minutes to 6 hours, for bullous impetigo it is 1 to 10 days, for toxic shock syndrome it is usually 2 days, and for other types of infection it is variable. 347 Carriage of S. aureus is most common in the anterior nares, but other sites, such as the hands, axilla, perineum, nasopharynx, and oropharynx, may also be involved. 339 The frequency of nasal carriage of S. aureus among health care personnel ranges between 20% and 90%, but fewer than 10% of healthy nasal carriers disperse the organisms into the air. 342 Nasal carriers with upper respirato ry symptoms can disseminate the organism more effectively. 342 Carriage of S. aureus in the nares has been shown to correspond to hand carriage, 336 and persons with skin lesions caused by S. aureus are more likely than asymptomatic nasal carriers to disseminate the organism.
Culture surveys of personnel can detect carriers of S. aureus but do not indicate which carriers are likely to disseminate organisms. Thus, such sur veys are not cost-effective and may subject per sonnel with positive culture results to unneces sary treatment and removal from duty. A more reasonable approach is to conduct active surveil lance for nosocomial S. aureus infections. Culture surveys may be indicated if, after a thorough epi demiologic investigation, personnel are linked to infections. Such implicated personnel can then be removed from clinical duties until carriage has been eradicated. 339,341, Several antimicrobial regimens have been used successfully to eradicate staphylococcal carriage in health care personnel. These regimens include orally administered antimicrobial agents (e.g., rifampin, clindamycin, or ciprofloxacin) alone or in combination with another oral (e.g., trimetho prim-sulfamethoxazole) or topical (mupirocin) antimicrobial. 349, Resistant S. aureus strains have emerged after the use of these oral or topical antimicrobial agents for eradication of S. aureus colonization. 18,210,349,353, Thus, antimicrobial treatment to eradicate carriage may be best if lim ited to personnel who are carriers epidemiological ly linked to disease transmission. Nosocomial transmission of S. aureus can be prevented by adherence to standard precautions and other forms of transmission-based precautions as needed. 3 Restriction from patient-care activities or food handling is indicated for personnel who have draining skin lesions that are infected with S. aureus until they have received appropriate thera py and the infection has resolved. No work restric tions are necessary for personnel who are colo nized with S. aureus, unless they have been epi demiologically implicated in S. aureus transmis sion within the facility.

# Streptococcus, group A infection
Group A Streptococcus (GAS) has been trans mitted from infected patients to health care per sonnel after contact with infected secretions,  and the infected personnel have subsequently acquired a variety of GAS-related illnesses (e.g., toxic shock-like syndrome, cellulitis, lymphangi tis, and pharyngitis). Health care personnel who were GAS carriers have infrequently been linked to sporadic outbreaks of surgical site, postpartum, or burn wound infections  and to food-borne transmission of GAS causing pharyngitis. 377 In these outbreaks, GAS carriage was documented in the pharynx, 369,372,378 the skin, 369,370 the rec tum, 369,375 and the female genital tract of the infected personnel. 369,374,379 The incubation period for GAS pharyngitis is 2 to 5 days, but for impetigo is 7 to 10 days. The incu bation period is variable for other GAS infections. 380 Culture surveys to detect GAS carriage among personnel are not warranted, unless personnel are epidemiologically linked to cases of nosocomial infection. 378 In instances where thorough epi demiologic investigation has implicated person nel in nosocomial transmission, cultures may be obtained from skin lesions, pharynx, rectum, and vagina; GAS isolates obtained from personnel and patients can be serotyped to determine strain relatedness. 373 Treatment of personnel carriers needs to be individually determined because (a) experience is limited regarding the treatment of personnel carriers implicated in GAS outbreaks and (b) carriage of the organism by personnel may be recurrent through long periods. 374 Contact is the major mode of transmission of GAS in these health care settings. Airborne transmis sion during outbreaks has been suggested by sev eral investigators, and some have demonstrated that exercising and changing of clothing can lead to airborne dissemination of GAS from rectal and vaginal carriage. 369,374,375,379 Nosocomial transmis sion of GAS to personnel can be prevented by adherence to standard precautions or other transmission-based precautions as needed. 3

# CDC Personnel Health Guideline 317
Restriction from patient care activities and food handling is indicated for personnel with GAS infec tions until 24 hours after they have received appro priate therapy. However, no work restrictions are necessary for personnel who are colonized with GAS, unless they have been epidemiologically linked to transmission of infection within the facility.

# Tuberculosis
Nosocomial transmission of tuberculosis (TB) is well documented, but such transmission in the United States is generally low. However, the risk may be increased in health care facilities located in communities with (a) high rates of HIV, (b) high numbers of persons from TB-endemic coun tries, and (c) communities with a high prevalence of TB infection. 381,382 In some areas in the United States, the incidence and prevalence of mul tidrug-resistant Mycobacterium tuberculosis (MDR-TB) have also increased, and nosocomial MDR-TB outbreaks have occurred.  The increased risk of occupational acquisition of TB by health care personnel has been reported for decades, and it dramatically decreased after the introduction of effective antituberculous drugs. 392,393 Skin-test conversion rates among health care personnel after routine skin testing have ranged from 0.11% to 10%. 394 Among health care personnel with known exposure to an infec tious patient with TB or involved in prolonged nosocomial outbreaks of TB, the skin-test conver sion rates have ranged from 18% to 55%. 383 385,388,389,393,395-401 Health care personnel with severely compromised immune systems, especial ly those infected with HIV 381,402 and including those with malignancies or receiving immuno suppressive therapy, are at high risk for develop ment of active disease after acquisition of tuber culous infection. It has been estimated that per sons infected with M. tuberculosis and coinfected with HIV have an 8% to 10% risk per year for development of active TB, whereas immunocom petent persons infected with TB have a 10% life time risk for active disease. 403 The transmission of TB in health care facilities has been primarily caused by incomplete imple mentation of recommended TB infection control measures. 396 In 1994, the CDC published detailed recommendations for the prevention of trans mission of TB in health care settings, "Guidelines for Preventing the Transmission of M. tuberculosis in Health Care Facilities, 1994." 382 A summary of the recommendations pertaining to personnel health follows.

# a. Strategies for prevention of transmission of TB
The risk of transmission of TB to or from per sonnel in a health care facility varies according to the type and size of the facility, the preva lence of TB in the community, the patient pop ulation served by the facility, the occupational group the person represents, the area of the facility where the person works, and the effec tiveness of the facility's TB control program. A detailed risk assessment is essential in identify ing the nature of TB control measures that are appropriate for a particular facility, as well as for specific areas and occupational groups within a facility. 382,404 A risk assessment should include the following: (a) review of the commu nity TB profile, (b) review of the number of patients with TB who were treated in each area of the facility, (c) review of the drug-suscepti bility patterns of TB isolates from patients treated in the facility, (d) an analysis of purified protein derivative (PPD) skin-test results of health care personnel by work area or occupa tional group, (e) an evaluation of infection con trol parameters, including isolation policies, laboratory diagnostic capabilities, and antitu berculous therapy regimens, (f) an observation al review of TB infection control practices, and (g) evaluation of the function and maintenance of environmental controls. 382 Transmission of TB can be minimized by developing and implementing an effective TB control program that is based on a hierarchy of controls: (a) administrative controls, (b) engi neering controls, and (c) personal respiratory protection. 382,384,386,393,396,404,405

# b. TB screening program
A TB screening program for personnel is an inte gral part of a health care facility's comprehensive TB control program. The screening program should be based on the facility-specific risk assess ment. It may be advisable to screen immunocom promised personnel every 6 months. 382 Baseline PPD testing of all personnel (including personnel with a history of bacille Calmette-Guerin  vaccination) during their preem ployment physical examination or their applica tion for hospital privileges will identify personnel who have been previously infected. For the base line testing, a two-step procedure for personnel without a PPD test in the past 12 months can be used to minimize the likelihood of confusing reac tivity from an old infection (boosting) with reac tivity from a recent infection (conversion). Decisions concerning the use of the two-step pro-AJIC June 1998 cedure for baseline testing in a particular facility should be based on the frequency of boosting in that facility. Criteria used for interpretation of a PPD-test reaction may vary depending on (a) the purpose (diagnostic or epidemiologic) of the test, (b) the prevalence of TB infection in the popula tion being tested, (c) the immune status of the host, and (d) any previous receipt of BCG immu nization. Detailed recommendations for perform ing and interpreting skin tests have been pub lished. 382,

# c. Follow-up evaluation
The risk assessment will show which health care personnel have the potential for exposure to M. tuberculosis and determine how frequently they should receive PPD testing. At a minimum, annual PPD testing is indicated for personnel with the potential for exposure to TB.
It is also important to obtain an initial chest radiograph for personnel with positive PPD-test reactions, documented PPD-test conversions, or pulmonary symptoms suggestive of TB. There are no data to support the use of routine chest radiographic examinations for asymptomatic PPD-negative personnel. In addition, personnel who have positive PPD-test reactions but also received adequate preventive treatment do not need repeat chest films, unless they have pul monary symptoms suggestive of TB. Repeat chest radiographic examinations of such persons have not been shown to be beneficial or costeffective in monitoring persons for development of disease. However, more frequent monitoring for symptoms of TB may be considered for per sonnel who had recent conversion of their PPD test and those persons who, if infected, are at increased risk for development of active TB (e.g., HIV-infected or otherwise severely immunocom promised persons). 382 Routine anergy testing of HIV-seropositive individuals is limited in its use fulness; however, anergy testing may be useful in guiding individual decisions regarding preven tive therapy in selected situations. 408

# d. Management of personnel after exposure to TB
It is important to administer PPD tests to per sonnel as soon as possible after TB exposures are recognized. Such immediate PPD testing estab lishes a baseline with which subsequent PPD tests can be compared. A PPD test performed 12 weeks after the last exposure will indicate whether infection has occurred. Persons already known to have reactive PPD tests need not be retested. Personnel with evidence of new infec tion (i.e., PPD-test conversions) need to be evalu ated for active TB. If active TB is not diagnosed, preventive therapy should be considered. 382

# e. Preventive therapy
For workers with positive PPD-test results who were probably exposed to drug-susceptible TB, preventive therapy with isoniazid is indicated, unless there are contraindications to such thera py. 382,407 Alternative preventive regimens have been proposed for persons who have positive PPD-test results after exposure to drug-resistant TB. 409

# f. Work restrictions
Personnel with active pulmonary or laryngeal TB may be highly infectious; exclusion from duty is indicated until they are noninfectious. If personnel are excluded from duty because of active TB, the facility should have documentation from their health care providers that personnel are noninfec tious before they are allowed to return to duty. The documentation needs to include evidence that (a) adequate therapy is being received, (b) the cough has resolved, and (c) results of three consecutive sputum acid-fast bacilli (AFB) smears collected on different days are negative. After personnel resume duty and while they remain on anti-TB therapy, periodic documentation from their health care providers is needed to show that effective drug therapy is being maintained for the recommended period and that their sputum AFB smear results continue to be negative. If personnel discontinue their treatment, they need to be evaluated for active TB; directly observed therapy may be considered.
Work restrictions are not necessary for person nel receiving preventive treatment for latent TB (positive PPD-test result without active disease) or for personnel with latent TB who do not accept preventive therapy. However, these personnel should be instructed to seek evaluation promptly if symptoms suggestive of TB develop.

# g. Considerations for BCG vaccine

# BCG has not been routinely used in the United
States to protect health care personnel. Never theless, because of the resurgence of TB in the United States and new information about the pro tective effect of BCG, 410,411 the role of BCG vaccina tion in the prevention and control of TB in the coun try has been reevaluated. 412 The following is a sum mary of the joint statement by the Advisory Council for the Elimination of Tuberculosis and ACIP regarding the use of BCG in health care personnel.
Two recent metaanalyses of 18 410 and 26 411 BCG studies, respectively, indicate that the efficacy of BCG vaccine in preventing serious TB is high (>80%) in children and suggest 50% efficacy in adults. However, the protective efficacy of the vac-CDC Personnel Health Guideline 319 cine in adolescents and adults, including health care personnel and HIV-infected children and adults, has not been determined. 412 BCG vaccination should not be used as a pri mary TB control strategy because (a) the protec tive efficacy of the vaccine in health care person nel is uncertain and (b) even if vaccination is effective in an individual, other persons in the health care facility are not protected against pos sible exposure to and infection with drug-resistant strains of M. tuberculosis. However, BCG vaccina tion may be indicated for health care personnel in a few geographic areas where the prevalence of MDR-TB is high, transmission of TB is likely, and TB infection control measures have been imple mented but have not been successful in control ling nosocomial transmission. 412 Consultation with local and state health departments is advis able when determining whether to provide BCG vaccination to health care personnel.
BCG vaccination often results in local adverse effects (such as muscular soreness, erythema, purulent drainage, and axillary or cervical lym phadenopathy) for as long as 3 months after vacci nation; serious long-term complications (such as musculoskeletal lesions, multiple lymphadenitis, and disseminated BCG disease) are infrequent.  The safety of BCG vaccination in immunocompro mised populations (i.e., immunocompromised from immune deficiency diseases, HIV infection, leukemia, lymphoma, or generalized malignancy, or immunosuppressed as a result of therapy with corticosteroids, alkylating drugs, antimetabolites, or radiation) has not been determined by adequate epidemiologic studies. However, because of the possibility of disseminated BCG infection in such persons,  BCG vaccination is not recommend ed for immunocompromised personnel. 412 The safety of BCG vaccination in pregnant women has also not been evaluated; therefore, it is not recom mended for pregnant personnel. 412 PPD testing is not contraindicated for persons who have received BCG vaccine and can be used to support or exclude the diagnosis of infection with M. tuberculosis. 412 PPD-test reactivity caused by BCG vaccination wanes with time  and is unlikely to persist longer than 10 years after vac cination in the absence of infection with M. tuber culosis. 420,421 After a person has been vaccinated with BCG, the presence or size of a PPD-test reac tion cannot be used to predict whether BCG will provide any protection against TB disease 423,424 or to determine whether the reaction is caused by M. tuberculosis infection or the previous BCG vaccination. 425 However, a BCG-vaccinated per son who has a PPD-test reaction of  10 mm induration should be considered infected with TB, especially if the vaccinee (a) is a contact of a person with infectious TB, particularly if the infectious person has transmitted M. tuberculosis to others, (b) is from a country with high preva lence of TB, or (c) is continually exposed to pop ulations in which the prevalence of TB is high. 412

# Vaccinia (smallpox)
Through aggressive surveillance for smallpox combined with the effective use of smallpox vac cine (vaccinia virus vaccine), the World Health Organization was able to declare the world free of smallpox in 1980. The smallpox vaccine licensed for use in the United States is derived from infec tious vaccinia virus. After vaccination, the virus can be cultured from the vaccination site until the scab has separated from the skin (2 to 21 days after vaccination); thus, susceptible persons may acquire vaccinia from a recently vaccinated per son.  Covering the vaccination site and wash ing hands after contact with the vaccination site (including bandages) will prevent transmission. Recently, recombinant vaccinia viruses have been engineered to express immunizing agents of sev eral viruses (e.g., herpesvirus, HBV, influenza). There is a theoretic risk that transmission could occur from contact with contaminated dressings or by contact with recombinant vaccine, but no such transmission has been reported among per sonnel who provide care to recipients of the recombinant vaccine. Infections also have been reported among laboratory personnel who handle viral cultures or materials contaminated with vac cinia or recombinant viruses. 18,162 Smallpox vaccination (every 10 years) is indicat ed for personnel who work directly with orthopox viruses (e.g., monkeypox, vaccinia, variola) or in animal care areas where orthopox viruses are stud ied. In selected instances, vaccination may be con sidered for personnel who provide care to recipients of recombinant vaccinia vaccine. 9,18 Personnel who receive the vaccine may continue to have contact with patients if the vaccination site is covered and handwashing is strictly observed. 18 Vaccine is not recommended for personnel with immunosuppres sion or eczema or for personnel who are pregnant.

# Varicella
Nosocomial transmission of varicella-zoster virus (VZV) is well recognized.  Sources for nosoco mial exposures have included patients, health care AJIC June 1998 personnel, and visitors (including the children of personnel) with either varicella or herpes zoster.
All susceptible adults in health care settings are at risk for varicella and its complications. During 1990 through 1994, fewer than 5% of varicella cases occurred among adults older than 20 years, but they accounted for 55% of varicella-related deaths. Certain persons are at higher risk for severe disease and secondary complications: preg nant women, premature infants born to varicellasusceptible mothers, infants born at less than 28 weeks' gestation or weighing  1000 gm (regard less of maternal immune status), and immuno compromised patients. 13 The incubation period for varicella is usually 14 to 16 days but may be from 10 to 21 days after exposure, although the incubation period may be shorter in immunocompromised persons. 442 In persons who receive postexposure VZV immune globulin, the incubation period may be as long as 28 days after exposure. Transmission of infection may occur from 2 days before onset of rash and usually as long as 5 days after rash onset. 442 VZV is transmitted by the contact with infect ed lesions and, in hospitals, airborne transmis sion has occurred from patients with varicella or zoster to susceptible persons who had no direct contact with the infected patient.  Adher ence to airborne and contact precautions when caring for patients with known or suspected VZV infection can reduce the risk of transmis sion to personnel. 3 It is generally advisable to allow only personnel who are immune to varicella to take care of patients with VZV. Because of the possibility of transmission to and development of severe illness in high-risk patients, personnel with localized zoster should not take care of such patients until all lesions are dry and crusted. 13,447 Personnel with localized zoster are not likely to transmit infection to immunocompetent patients if their lesions can be covered. However, some institutions may exclude personnel with zoster from work until their lesions dry and crust. 439

# a. Varicella screening and vaccination
Serologic tests have been used to assess the accuracy of reported histories of chicken pox. 440, In adults, a history of varicella is highly predictive of serologic immunity (97% to 99% seropositive). Most adults who have negative or uncertain histories of varicella are also seropositive (71% to 93%). In health care institutions, serologic screening of personnel who have negative or uncertain histories is likely to be cost-effective, depending on the rel ative costs of the test and vaccine. 9,13 A variety of methods have been used for detect ing varicella antibody, but a commercially avail able latex agglutination test provides prompt, sen sitive, and specific serologic results at a reason able cost. The latex agglutination test may not detect low levels of protective antibody that can occur after vaccination; however, a test with increased sensitivity and specificity is currently under development. Routine testing for varicella immunity after vaccination is not necessary, because 99% of persons are seropositive after the second dose. Moreover, seroconversion does not always result in full protection against disease. However, testing vaccinees after exposures may be warranted. In addition, vaccinated persons who are exposed to varicella but lack antibody may be retested in 5 to 6 days to determine whether they are antibody seropositive after the second test and therefore unlikely to acquire varicella. 13 In March 1995, a live-attenuated varicella vac cine was licensed for use in the United States. Administration of varicella vaccine is recom mended for all susceptible health care person nel, especially those who will have close contact with persons at high risk for serious complica tions. 9,13,451,452 Effective varicella vaccination pro grams require two doses of vaccine to achieve high seroconversion rates in adults; 451 the need for and response to booster doses of vaccine are unknown. Vaccination provides approximately 70% protection against infection and 95% pro tection against severe disease in follow-up from 7 to 10 years after vaccination. 13 Cases of vari cella have occurred among vaccinees after expo sure to wild-type virus ("breakthrough infec tion"). Data from vaccine trials in which vacci nees of all ages were followed up for as long as 9 years indicate that 1% to 4% of vaccine recip ients per year acquire varicella, depending on the vaccine lot and interval after vaccination. 9,13 However, vaccinated persons have milder dis ease (e.g., afebrile, a mean of 50 skin lesions that are often not vesicular, and shorter duration of illness) than do unvaccinated individuals (e.g., febrile with several hundred vesicular lesions) 453,454 and are less likely to transmit dis ease than unvaccinated persons.
The rate of transmission of disease from vac cinees who contract varicella is low for vacci nated children but has not been studied in adults. Active surveillance for 1 to 8 years after vaccination of 2141 children between 1981 and CDC Personnel Health Guideline 321 1989 in 10 different trials 9 resulted in reports of breakthrough infections in 78 children, which further resulted in secondary cases in 12.2% (11/90) of vaccinated siblings. Illness was mild in both index and secondary cases. There also has been a report of transmission from a vacci nated child in whom breakthrough disease occurred to a susceptible mother. 9 All information currently available on vaccine efficacy and the persistence of antibody in vac cinees is based on research conducted in set tings where infection is highly prevalent and not affected by the wide use of vaccine. Thus, the extent to which the protection provided by vac cination has been increased by boosting from exposure to natural virus and whether longer term immunity may wane as the prevalence of natural VZV decreases are unknown.

# b. Transmission of vaccine virus
In clinical trials, 3.8% of children and 5.5% of adolescents and adults acquired a nonlocalized rash (median five lesions) after the first injection, and 0.9% of adolescents and adults acquired a nonlocalized rash after the second injection. Available data suggest that healthy children have limited potential to transmit vaccine virus to sus ceptible contacts (estimated to be <1%) but that the risk of transmission from immunocompro mised vaccinees is higher. 13,455,456 Tertiary trans mission of vaccine virus to a second healthy sib ling of a vaccinated leukemic child has also occurred. 456 These data suggest that healthy, vac cinated individuals have a very small risk of trans mitting vaccine virus to their contacts; this risk may be higher in those who acquire a varicellalike rash after vaccination.
Although the risk of transmission of vaccine virus from vaccinees is not known, the risk if any appears to be very low, and the benefits of vacci nating susceptible health care personnel clearly outweigh this potential risk. As a safeguard, insti tutions may wish to consider precautions for vac cinated personnel who acquire a rash or who will have contact with susceptible persons at high risk for serious complications.

# c. Management of health care personnel exposed to varicella
When unvaccinated susceptible personnel are exposed to varicella, they are potentially infec tious 10 to 21 days after exposure, and exclusion from duty is indicated from the tenth day after the first exposure through the 21st day after the last exposure, or until all lesions are dry and crusted if varicella occurs (Table 3). 256 June 1998 If vaccinated health care personnel are exposed to varicella, they may be serotested immediately after exposure to assess the presence of anti body. 452 If they are seronegative, they may be excluded from duty or monitored daily for devel opment of symptoms. Exclusion from duty is indi cated if symptoms (fever, upper respiratory tract symptoms, or rash) develop.
Vaccination should be considered for exposed unvaccinated health care personnel without docu mented immunity. 441,452 Because the efficacy of postexposure vaccination is unknown, however, persons vaccinated after an exposure should be managed as previously recommended for unvaccinated persons.
The routine postexposure use of VZV immune globulin (VZIG) is not recommended among immunocompetent health care personnel. 13 VZIG can be costly, does not necessarily prevent varicel la, and may prolong the incubation period by a week or more, thus extending the time that per sonnel will be restricted from duty. The use of VZIG may be considered for immunocompro mised (e.g., HIV infected) or pregnant health care personnel. 13,457 Postexposure use of acyclovir may be effective and less costly than the use of VZIG in some susceptible persons. 457 However, additional data concerning the efficacy of acyclovir for postexposure prophylaxis are needed before such use can be recommended. 9,13,441,458

# Viral respiratory infections
Viral respiratory infections are common prob lems in health care settings. Nosocomial respira tory infections can be caused by a number of viruses, including adenoviruses, influenza virus, parainfluenza viruses, respiratory syncytial virus (RSV), and rhinoviruses. Because influenza and RSV substantially contribute to the morbidity and mortality associated with viral pneumonia and both have been well studied epidemiologically, this section focuses on prevention of these two viral infections among personnel. Additional information on influenza and RSV can be found in the "Guideline for Prevention of Nosocomial Pneumonia." 459 a. Influenza Nosocomial transmission of influenza has been reported in acute and long-term care facil ities.  Transmission has occurred from patients to health care personnel, 462,464 from health care personnel to patients, 466 and among health care personnel. 465, Influenza is believed to be transmitted from person to person by direct deposition of virus-CDC Personnel Health Guideline 323 laden large droplets onto the mucosal surfaces of the upper respiratory tract of an individual during close contact with an infected person, as well as by droplet nuclei or small-particle aerosols. 21,290,473 Although the extent of transmission by virus-con taminated hands or fomites is not known, it is not the primary mode of transmission. 473 The incubation period of influenza is usually 1 to 5 days, and the period of greatest communica bility is during the first 3 days of illness. However, virus can be shed before the onset of symptoms and as long as 7 days after illness onset.  Persons at greatest risk for influenzarelated complications include (a) persons older than 65 years, (b) residents of nursing homes and other chronic care facilities, (c) persons with chronic pulmonary or cardiovascular conditions, and (d) persons with diabetes mellitus. 17 Adherence to droplet precautions may prevent nosocomial transmission. 3 Administration of influenza vaccine to health care personnel, including pregnant women, 9 before the beginning of each influenza season can help to (a) reduce the risk to health care personnel of influenza infection, (b) prevent transmission of influenza from personnel to persons at high risk for complications, and (c) reduce personnel absenteeism during community outbreaks. Innovative methods may be needed to increase influenza immunization rates among health care personnel. 477 Immunization rates may also be increased by providing data to health care person nel on the low rates of systemic reactions to influenza vaccine among healthy adults. 478 During institutional outbreaks of influenza, prophylactic antiviral agents (e.g., amantadine and rimantadine) may be used in conjunction with influenza vaccine to reduce the severity and duration of illness among unvaccinated health care personnel. Amantadine and rimanta dine may be administered for 2 weeks after per sonnel vaccination or, in unvaccinated person nel, for the duration of influenza activity in the community. 17,459,465,479

# b. Respiratory syncytial virus
Nosocomial transmission of respiratory syncy tial virus (RSV) is greatest during the early winter when community RSV outbreaks occur; patients, visitors, and health care personnel may transmit the virus in the health care setting. RSV infection is most common among infants and children, who are likely to acquire more severe disease. Because RSV infection can also occur simultaneously with other respiratory viruses, it may go unrecog nized. 480,481 Nosocomial transmission has been reported most frequently among newborn and pediatric patients, 482,483 but outbreaks associated with substantial morbidity and mortality have been reported among adults in bone-marrow transplant centers, 484 intensive care units, 485 and long-term care facilities. 486,487 RSV is present in large numbers in the respira tory secretions of persons symptomatically infect ed with the virus and can be transmitted directly through large droplets during close contact with such persons or indirectly by hands or fomites that are contaminated with RSV. Hands can become contaminated through handling of infect ed persons' respiratory secretions or contaminat ed fomites and can transmit RSV by touching the eyes or nose. 459 The incubation period ranges from 2 to 8 days; 4 to 6 days is most common. In general, infected persons shed the virus for 3 to 8 days, but young infants may shed virus for as long as 3 to 4 weeks. Adherence to contact precautions effectively prevents nosocomial transmission.

# c. Work restrictions
Because large numbers of personnel may have viral respiratory illnesses during the winter, it may not be possible to restrict infected personnel from all patient care duties. Nevertheless, it may be prudent to restrict personnel with acute viral respiratory infections from the care of high-risk patients during community outbreaks of RSV and influenza. 488

# F. PREGNANT PERSONNEL
Immunologic changes occur during pregnancy, primarily depression of certain aspects of cell-medi ated immunity such as decreased levels of helper T cells. These changes permit fetal development with out rejection but generally do not increase maternal susceptibility to infectious diseases. Occupational acquisition of infections is of special concern to female health care personnel of childbearing age for several reasons. Some infections, such as varicella, may be more severe during pregnancy. Transplacental infections with viruses such as par vovirus, varicella, and rubella have been associated with abortion, congenital anomaly, and mental retardation. Other diseases in which the infectious agent may be transmitted to the fetus include CMV, hepatitis B, herpes simplex, influenza, and measles. In addition, certain drugs used to treat or prevent some infections, for example tuberculosis, may be contraindicated during pregnancy.
In general, pregnant health care personnel do not have an increased risk for acquiring infections AJIC June 1998 in the workplace. The risks to pregnant personnel and methods for prevention are discussed in the various sections of this document and are sum marized in Table 6. Female personnel of child bearing age should be strongly encouraged to receive immunizations for vaccine-preventable diseases before pregnancy. Such personnel may also decrease their risk of acquiring infection by adhering to appropriate infection control prac tices, including standard precautions when caring for all patients. Additional information on occu pational risks for pregnant health care personnel has been published elsewhere. 

# G. LABORATORY PERSONNEL
Despite the availability of improved engineering controls, work practices, and personal protective equipment, laboratory personnel remain at risk for occupational acquisition of infectious agents. 5,18,53,151,162,241,492,493 Furthermore, newer technologies that require the use of large or con centrated specimens may further increase the risk of occupationally acquired infections among lab oratory personnel. 494 In a review of laboratory-acquired infections from 1950 through 1974, more than 4000 labora tory-associated infections were documented in the United States 492 ; the 10 most commonly reported infections were brucellosis, Q fever, hepatitis (especially hepatitis B), typhoid fever, tularemia, tuberculosis, dermatomycosis, vene zuelan equine encephalitis, psittacosis, and coc cidioidomycosis. However, laboratory-associated infections also have been caused by a wide vari ety of other pathogens. 162,492,493 More recently, viral agents have accounted for a larger propor tion of laboratory-associated infections than have bacterial agents.  Laboratory personnel may acquire infection by aerosolization of specimens, mouth pipetting, or percutaneous injury. Information on the risks of laboratory-associated infections and appropriate biosafety procedures and precautions for labora tories have been published. 5,6,494,499,500 In addition to biosafety precautions, preventive measures (e.g., immunizations and postexposure prophylaxis) may also be indicated for laboratory personnel who handle infectious agents. In this document, disease-specific information and guid ance are provided for prevention of laboratoryassociated infections and for management of labo ratory personnel exposed to infectious agents. Health care institutions need to ensure that labo ratory personnel who may be exposed to infectious agents are well informed about the risks of acquir ing infections and about biosafety procedures to prevent transmission of infectious agents.

# H. EMERGENCY-RESPONSE PERSONNEL
Emergency medical technicians, firefighters, policemen, and others who attend to and trans port patients to the hospital may be exposed to recognized or undiagnosed transmissible infec tious diseases in the patients with whom they come in contact. Subtitle B (42 USC 300ff-80) of the 1990 Ryan White Comprehensive AIDS Resources Emergency Act requires the establish ment of notification systems in each state to ensure that emergency-response employees (including emergency medical technicians, fire fighters, and the like) are informed when they have been exposed to an emergency medical patient with an infectious, potentially fatal disease such as HIV or meningococcemia. CDC published a list of diseases for which emergency-response employees must be informed of an exposure. 501

# I. LATEX HYPERSENSITIVITY
Since the introduction of universal precautions, the use of latex gloves has become commonplace in health care settings. 31,502 The increased use of latex gloves has been accompanied by increasing reports of allergic reactions to natural rubber latex among health care personnel.  Natural rubber latex is a combination of heatand water-soluble proteins derived from the tree Hevea braziliensis. Reactions to latex gloves may be localized or systemic and include dermatitis, conjunctivitis, rhinitis, urticaria, angioedema, asthma, and anaphylaxis.  Most local reac tions associated with latex glove use are not immunologically mediated and result from chem icals (e.g., thiurams, carbamates, mercaptoben zothiazole, phenylenediamine), accelerants or antioxidants added to gloves during manufactur ing. 502,507, It may be clinically difficult to dif ferentiate irritant reactions from allergic contact dermatitis reactions; both may be manifested by itching, dryness, erythema, bleeding, or scaling of the hands. Nevertheless, neither of the types of local reactions to latex gloves are good predictors of latex allergy 503,516 ; only a subset of health care personnel reporting glove-associated skin irrita tion will have immunoglobulin E (IgE) antibod ies specific for latex. 513, In contrast, systemic reactions to natural rub ber latex, including urticaria, are mediated by antilatex IgE antibodies 509,520,521 and may result CDC Personnel Health Guideline 325 from direct skin contact or from exposure to air borne latex allergen adsorbed to glove powder. Occupational asthma from latex is becoming increasingly recognized. 520, Asthmatic responses to latex may occur early (8 hours) after exposure.  Local reactions (i.e., irritant or allergic contact dermatitis) to latex gloves account for most reported reactions among health care person nel. 503,506 The risk of progression from localized to systemic reactions is unknown.
Latex gloves may vary considerably in total protein content from brand to brand and from lot to lot within brands. 528,529 However, the total protein concentrations and allergenicity of latex gloves are not always directly correlated, 528 sug gesting that total protein concentrations are not necessarily a measure of the allergenic proper ties of latex gloves. Currently, the amount of latex allergen exposure required to produce sen sitization or to elicit reactions in previously sen sitized persons is unknown. The FDA has man dated labeling of all medical devices that contain natural rubber latex. 530 Another recognized contributor to latex sensiti zation and reactions is the powder or cornstarch used as a lubricant for gloves. Levels of extractable protein and allergen in a given glove have been shown to be correlated with the pres ence of powder. Also, investigators have demon strated that latex proteins adhere to the powder on gloves and that aerosolized latex protein-pow der particles can provoke allergic respiratory symptoms if inhaled by a latex-sensitive individ ual 531 ; similar adherence has not been detected with powdered vinyl gloves. In one study, person nel wearing powdered latex gloves had a signifi cantly higher rate of reaction than did workers who wore washed latex gloves, from which the powder had been removed (60% vs 28%); none of these workers had positive skin-test reactions to industrial or commercial cornstarch or powder. 504 Although many health care personnel or clini cians may implicate the powder or cornstarch on gloves as the cause of their reactions, documented reactions to cornstarch powder are rare.

# a. Prevalence and risk factors
In studies of health care personnel, the reported prevalence of IgE-mediated allergy to latex varies considerably, ranging from 2.9% to 17%. The broad range of prevalence rates reported likely represent differences in the personnel groups studied and the methods used for estimating sen sitization or allergy. 518,519,522,532,533 The prevalence detected in some studies also has been biased by enrollment or testing of only personnel with symptoms. 504,508 However, it is estimated that a minority of health care personnel seek medical evaluation or treatment for latex-allergic condi tions, even if they have symptoms. Thus, the true prevalence of these reactions among health care personnel is unknown.
The prevalence of sensitization to latex among health care personnel has been shown to vary by job category and by location within a facility. 506,533 In one study of 224 health care personnel, the overall prevalence of skin-prick reactivity to latex was 17% but ranged from 0% (0/17) among house keepers and clerical workers to 38% (5/13) among dental residents and assistants. 506 In another sur vey of 512 health care personnel, the prevalence among physicians (6.5%, 7/108) was greater than that among nurses (2.2%, 7/325) or other hospital personnel (1.3%, 1/79). Also, operating room per sonnel (6.2%, 9/145) were significantly more like ly to be sensitized than were personnel assigned to general wards or laboratories (1.6%, 6/367); oper ating room nurses had fourfold the prevalence of general ward nurses (5.6% vs 1.2%). 533 Measurable levels of latex aeroallergen have been detected in the breathing zones of operating room personnel and may vary as much as 100-fold, depending on the invasiveness of the procedure and frequency of glove changes. 534 Several factors have been linked with latex sen sitization among health care personnel, including the presence of other allergic conditions (e.g., asthma, eczema, hay fever), 503,516,518,519,522,532,533 nonwhite ethnicity, 519,532 elevated total IgE lev els, 519 allergy to cosmetic powders or foods, 535 years or status (full-time vs part-time) of employ ment, and frequency or duration of glove use. 503,516,522,533 Coexistent allergy to certain fruits (e.g., bananas, 536,537 avocados, 538,539 and chest nuts 540 ) also has been described in latex-allergic health care personnel.
Skin irritation and eczematous dermatitis 516,533 (conditions that may allow passage of latex pro teins through the skin) and use of other latex products (e.g., condoms, diaphragms) have not been consistently linked to latex sensitization in health care personnel.

# b. Diagnosis and identification
Diagnosis of latex allergy in personnel relies largely on a clinical history of symptoms elicited by exposure to latex products (e.g., balloons, gloves). Clinical symptoms, such as urticaria, may be good predictors of IgE-medicated allergy. 516,519 AJIC June 1998 A variety of methods have been used to aid in the identification of latex-allergic persons; most are experimental and have not been approved for clinical use. Skin-prick testing may be the most sensitive method for diagnosis of IgE-mediated allergy, but no standardized FDA-approved anti gen is currently available in the United States for detection of latex-specific IgE antibodies. Moreover, the use of some skin-test reagents in highly sensitized persons has been associated with adverse outcomes, 541 suggesting that these nonstandardized reagents may not be safe for rou tine use. In Europe, where a standardized testing antigen has been developed, skin-prick testing has been used successfully.
FDA-approved immunoassays are available for detection of latex-specific IgE antibodies in blood. The FDA has recommended that these assays be used as confirmatory tests, rather than screening tests, for persons in whom latex allergy is sus pected on the basis of clinical history and find ings. Levels of detectable antibody appear to be associated with symptoms, 504,519 but, as with other allergens, the correlation between serum concen trations of latex-specific IgE antibodies and symp tom severity may not be predictable. 312,504,516

# c. Prevention strategies
Avoiding latex products remains the cornerstone of preventing sensitization (primary prevention) and reactions (secondary prevention) to natural rubber latex products. Proposed strategies to reduce the risk of reactions to natural rubber latex have included the use of the following: (a) nonla tex (e.g., vinyl) products alone or in combination with latex gloves, (b) powder-free latex gloves, (c) powdered latex gloves washed to remove powder, and (d) "low-protein" latex gloves. However, none of these interventions has been prospectively stud ied in controlled trials to assess cost-effectiveness or efficacy in preventing sensitization or reactions.
Because latex proteins can be aerosolized when powdered gloves are donned or removed, systemic symptoms caused by latex aeroallergens may not be alleviated by simply avoiding latex products, particularly if coworkers of the affected worker continue to use powdered latex gloves. Although the risk of a worker's exposure is greatest when gloves are donned or removed, allergenic proteins also may settle on environmental surfaces, surgi cal gowns, or other clothing and become resus pended. The use of powder-free or low-protein gloves appears more effective and less costly than either laminar-flow or high-efficiency particulate air-filtered glove-changing stations in reducing latex aeroallergens. 534 For personnel with sys temic manifestations of latex allergy, workplace restriction or reassignment may be necessary.

# J. THE AMERICANS WITH DISABILITIES ACT
The Americans With Disabilities Act provides guidelines for hiring and placing employees with disabilities, as defined in the Act.  In general, employers must assess applicants for their qualifications to perform the tasks inher ent to the job for which the employee is being considered. Applicants may be asked about their ability to perform specific job functions but may not be asked about the existence, nature, or severity of a disability. Employers must make a "reasonable accommodation" to allow an indi vidual to perform the essential functions of a job, unless the employer can prove that this would create undue hardship because of signifi cant difficulty or expense.
The provisions of the Americans With Disabilities Act need to be incorporated into infec-CDC Personnel Health Guideline 327 tion control policies for health care personnel. For example, applicants with a communicable disease spread by aerosol could justifiably be denied employment (until they are no longer infectious) because they could pose a direct threat to others. On the other hand, applicants who are immuno compromised may not necessarily be excluded because of an increased risk for acquiring an infection in the hospital if the employer can make reasonable accommodations that prevent expo sure. Health care personnel who are known to be immunocompromised need to be referred to per sonnel health professionals who can individually counsel the employees on their risk for infection. At the request of the immunocompromised health care personnel, employers should offer but not compel a work setting in which health care per sonnel would have the lowest possible risk for occupational exposure to infectious agents. Evaluation of individual situations also needs to include consideration of the provisions of other applicable federal, state, and local laws.

# A. INTRODUCTION
In this document, the term health care personnel refers to all paid and unpaid persons working in health care settings who have the potential for exposure to infectious materials including body substances, contaminated medical supplies and equipment, contaminated environmental sur faces, or contaminated air. These personnel may include but are not limited to physicians, nurses, technicians, therapists, pharmacists, nursing assistants, laboratory personnel, autopsy person nel, emergency medical service personnel, dental personnel, students and trainees, contractual staff not employed by the health care facility, and per sons not directly involved in patient care but potentially exposed to infectious agents (e.g., vol unteer, dietary, housekeeping, maintenance, and clerical personnel).
As in previous CDC guidelines, each recommen dation is categorized on the basis of existing sci entific data, theoretic rationale, applicability, and potential economic impact. The system for cate gorizing recommendations is as follows:
Category IA Strongly recommended for all hospitals and strongly supported by well-designed experimental or epidemiologic studies.

# Category IB
Strongly recommended for all hospitals and reviewed as effective by experts in the field and a consensus of Hospital Infection Control Practices Advisory Committee members on the basis of strong rationale and suggestive evi dence, even though definitive scientific studies have not been done.

# Category II
Suggested for implementation in many hospi tals. Recommendations may be supported by sug gestive clinical or epidemiologic studies, a strong theoretic rationale, or definitive studies applica ble to some but not all hospitals.

# No recommendation; unresolved issue
Practices for which insufficient evidence or consensus regarding efficacy exists.  8,9 (b) well informed about indications, storage, dosage, preparation, side effects, and contraindications for each of the vaccines, toxoids, and immune globu lins used, 8,9,24 and (c) kept updated on nation al and local recommendations regarding vac cination of health care personnel (Tables 1  and 2). Category IB 3. Ensure that immunization product informa tion is available at all times and that a perti nent health history, especially a history of allergy and potential vaccine contraindica tions, is obtained from each person before an agent is given (Table 2). Category IB 4. Develop a list of needed immunizations for each employee during screening and an indi vidual plan to provide the necessary vac cines. Category IB 5. In the absence of a known occupational exposure, provide personnel with on-site immunizations or refer personnel to their own health care providers for routine non-occupation-related immunizations against diphtheria, pneumococcal disease, hepatitis A, or tetanus (Table 1). Category IB 6. Provide vaccine to personnel who may have occupational exposure to uncommon dis-

# Bloodborne pathogens, general recommen dation
Ensure that health care personnel are famil iar with precautions to prevent occupational transmission of bloodborne pathogens. 3,6,30,31,39 Category IA Follow state and federal guidelines and strategies for determining the need for work restrictions for health care personnel infected with bloodborne pathogens. 48 1). 9 Category IA e. Administer rubella vaccine- in the postpar tum period to female personnel not known to be immune. Category IA f. Exclude susceptible personnel who are exposed to rubella from duty from the sev enth day after the first exposure through the 21st day after the last exposure (Table 3). 9 Category IB g. Exclude personnel who acquire rubella from duty until 7 days after the beginning of the rash (Table 3 3). 369 371,374 Category IB b. Do not routinely exclude personnel with sus pected or confirmed carriage of group A Streptococcus from patient care or food han dling unless it is shown epidemiologically that they are responsible for disseminating the organism in the health care setting (Table 3). 369,373,378  1) Exclude personnel with infectious pul monary or laryngeal TB from the workplace until the facility has documentation from their health care provider that they are receiving adequate therapy, their coughs have resolved, and that they have had three consecutive sputum smears collected on dif ferent days with negative results for AFB. After personnel return to work, obtain peri odic documentation from their health care provider that effective drug therapy has been maintained for the recommended peri od and that sputum smear results remain negative for AFB (  1). 9,18 Category IB b. Consider administering vaccinia vaccine to personnel who provide clinical care to recip ients of recombinant vaccinia virus vaccines (Table 1). 9,18 Category II c. Do not administer vaccinia vaccine to pregnant personnel or personnel with immunosuppres sion or eczema (Tables 1 and 2). Category IB d. Do not exclude from duty personnel who receive the vaccine, if they keep the vaccina tion site covered and adhere to handwashing practices. 18 Category IB

# Varicella
a. Administer varicella vaccine to susceptible personnel, especially those that will have contact with patients at high risk for serious complications (Table 1). 9,13 Category IA b. Do not perform serologic screening of per sons with negative or uncertain history of varicella before administering varicella vac cine to personnel, unless the institution con siders it cost-effective. 9,13 Category IB c. Do not routinely perform postvaccination testing of personnel for antibodies to vari cella. 9 Category IB d. NO RECOMMENDATION for administering postexposure varicella vaccination for the protection of exposed, susceptible person nel. 9 UNRESOLVED ISSUE e. Develop guidelines for managing health care personnel who receive varicella vaccine; for example, consider precautions for personnel who acquire a rash after receipt of varicella vac cine and for other health care personnel who June 1998 receive varicella vaccine and will have contact with susceptible persons at high risk for serious complications from varicella. 9 Category IB f. Develop written guidelines for postexposure management of vaccinated or susceptible personnel who are exposed to wild-type vari cella. 9 Category IB g. Exclude personnel from work who have onset of varicella until all lesions have dried and crusted (Table 3). 3 Category IB h. Exclude from duty after exposure to varicella personnel who are not known to be immune to varicella (by history or serology), begin ning on the tenth day after the first exposure until the 21st day after the last exposure (28th day if VZIG was given; Table 3). 9 Category IB i. Restrict immunocompetent personnel with localized zoster from the care of high-risk patients until lesions are crusted; allow them to care for other patients with lesions cov ered. 9 Category IB j. Restrict immunocompromised personnel with zoster from contact with patients until their lesions are crusted (Table 3). 9 Category IB k. Restrict susceptible personnel exposed to zoster from patient contact from the tenth day after the first exposure through the 21st day after the last exposure (28th day if VZIG was given; Table 3). 9 Category IB l. Perform serologic screening for immunity to varicella on exposed personnel who have not had varicella or are unvaccinated against varicella. 9,13 Category IB m. Consider performing serologic screening for immunity to varicella on exposed, vacci nated personnel whose antibody status is not known. If the initial test result is negative, retest 5 to 6 days after exposure to determine whether an immune response occurred. Category IB n. Consider excluding vaccinated personnel from work beginning on the 10th day after the first exposure through the 21st day after the last exposure if they do not have detectable antibodies to varicella, or screen daily for symptoms of varicella (Table 3). 9 Category IB o. Do not routinely give VZIG to exposed sus ceptible personnel, unless immunosup pressed, HIV infected, or pregnant. If VZIG is given, exclude personnel from duty from the 10th day after the first exposure through the 28th day after the last exposure (Tables 1  and 3). 9,13 Category IB

# Viral respiratory infections
a. Administer influenza vaccine annually to all personnel, including pregnant women, before the influenza season, unless otherwise contraindicated (Table 1). 9,17 Category IB b. Consider the use of antiviral postexposure prophylaxis for unvaccinated health care per sonnel during institutional or community outbreaks of influenza for the duration of influenza activity, or consider giving vaccine to unvaccinated personnel and providing them with antiviral postexposure prophylaxis for 2 weeks after vaccination (Table 1). 3,17,459 Category IB c. Consider excluding personnel with acute febrile respiratory infections or with lab oratory evidence of epidemiologically significant viruses from the care of highrisk patients (e.g., neonates, young infants, patients with chronic obstructive lung disease, and immunocompromised patients) during community outbreaks of influenza or RSV infections (Table 3). 3

# Category IB

# H. SPECIAL ISSUES
1. Pregnancy a. Counsel pregnant women and women of childbearing age regarding the risk of transmission of particular infectious dis eases (e.g., CMV, hepatitis, herpes simplex, HIV, parvovirus, rubella) that, if acquired during pregnancy, may have adverse effects on the fetus, whether the infection is acquired in nonoccupational or occupa tional environments. Provide such women with information on standard and transmission-based precautions appropriate for each infection (Table 6). 3, Category IB b. Do not routinely exclude women only on the basis of their pregnancy or intent to be pregnant from the care of patients with particular infections that have potential to harm the fetus (e.g., CMV, HIV, hepatitis, herpes simplex, parvovirus, rubella, and varicella; Table 6).  Category IB a. Develop an institutional protocol for (1) evaluating and managing personnel with suspected or known latex allergy, (2) establishing surveillance for latex reac tions within the facility, (3) purchasing gloves, and (4) measuring the impact of preventive measures. Educational materi als and activities should be provided to inform personnel about appropriate glove use and the manifestations and potential risk of latex allergy. 31,546 Category IB b. Glove purchasers should review information on the barrier effectiveness of gloves and consider worker acceptance (e.g., comfort and fit) when selecting gloves for use in the health care organization. 31, Category IB c. To facilitate the appropriate selection of gloves, the occupational health service should maintain a list of all gloves used the institution according to whether they do or do not contain latex. Category II d. Evaluate personnel with symptoms sugges tive of latex allergy (e.g., localized dermati tis and workplace-related asthma). 522 Use serologic tests only for those who, on the basis of this evaluation, have suspected latex allergy. 504,516 Category IB e. Avoid the use of all latex products by per sonnel with a history of systemic reactions to latex. 520, Category IB f. Use nonlatex gloves for personnel with localized reactions to latex. 502,507, Category IB The opinions of all the reviewers might not be reflected in all the rec ommendations contained in this document.