Update: Investigation of Bioterrorism-Related Anthrax -Continued had no evidence of B. anthracis exposure by nasal swab testing. No cases of disease have been identified among postal workers. On the basis of the positive environmental swabs, focused clean-up procedures continue at regional and local postal centers. The Environmental Protection Agency (EPA), in consultation with health officials, is conducting decontamination of the work site. Approximately 1,100 persons were started on antimicrobial prophylaxis for suspected B. anthracis exposure; 555 worked either full-or part-time in the affected building. The majority of other persons reported spending at least 1 hour in the affected building since August 1. Additional follow-up for compliance with prophylaxis recommendations and monitoring adverse events associated with long-term antimicrobial prophylaxis is ongoing.Investigations in NYC have identified five (three confirmed and two suspected) cutaneous anthrax cases; three cases (one confirmed and two suspected) have been identified since the last report (1 ). These five cases were associated with four media companies (A-D). The two previously reported cases were related to work sites A and B, and the three additional cases were related to work sites C, D, and A, respectively. No cases among postal workers have been identified. On October 1, a 27-year-old woman who regularly handled mail at work site C sought medical care at a local hospital for two lesions on the left cheek, which developed surrounding erythema and edema and local adenopathy. A biopsy obtained on October 16 was positive by IHC staining for the cell wall antigen of B. anthracis and serologic testing was weakly reactive. No suspicious letter was identified from her work site. Two suspected cases of cutaneous anthrax also have been detected. The first suspected case, a 29-year-old woman with onset of illness on September 22, frequently handled mail at work site D. At her work site, an unopened letter postmarked September 18, which contained powder contaminated with B. anthracis was found on October 19. The second suspected case, a 23-year-old woman with onset of illness on September 28, handled a suspicious letter postmarked September 18 from work site A. All three patients were treated with ciprofloxacin and have shown clinical improvement. A total of three persons were confirmed by nasal swabs to have been exposed to B. anthracis, presumably acquired during handling and processing of specimens during the investigation of the first confirmed case (1 ). In work site A, potentially exposed persons were identified and prescribed antimicrobial prophylaxis. An environmental investigation of work site A was conducted subsequently; environmental samples taken from work site A were culture-positive for B. anthracis. Of 1,360 persons who were tested by nasal swabs from work site A, all were confirmed negative. Nasal swabs were obtained from 1,202 persons from work sites B, C, and D; 1,183 tested negative and 19 are pending final results. Environmental samples taken from work site A were positive. Testing of environmental specimens from work sites B, C, and D is ongoing. Prophylaxis was recommended for potentially exposed persons at work site A. Antimicrobial prophylaxis was initiated for nine persons who had recent contact with the sealed letter containing B. anthracis in work site D. Vol. 50 / No. 42 MMWR 911 Update: Investigation of Bioterrorism-Related Anthrax -ContinuedTo date, investigations in New Jersey and Pennsylvania have identified four (two confirmed and two suspected) anthrax cases. Cutaneous disease has been diagnosed in three patients and one has illness suspected to be inhalational anthrax, but laboratory tests to confirm the diagnosis are pending. All four of these patients worked at one of two postal facilities in New Jersey. Although no specific contaminated letter was identified, contaminated letters destined for both NYC and DC passed through at least one of these postal facilities in New Jersey. On October 1, a 45-year-old female mail carrier sought medical care at a local hospital for a 4-day history of worsening skin lesions on her right forearm. A biopsy was obtained and arrived at CDC on October 17 and later that night was found positive by IHC. In addition, tissue was positive for B. anthracis by polymerase chain reaction (PCR), and serologic testing was reactive. The patient's condition improved on antimicrobial therapy. On October 16, a 35-year-old male mail processor, with a history of a chronic, bullouslike skin condition, was taken to a local hospital complaining of a 2-day history of a large pustular lesion on his neck. He returned 1 day later with increasing ulceration of the skin lesion associated with fatigue, chills, and a swollen throat; he was afebile but had vesicles and bullae around the pustular lesion. Biopsy was positive by IHC, and serologic testing was reactive to B. anthracis. The patient's lesions responded to antimicrobial therapy. Two suspected cases also have been detected. The first case occurred in a 39-yearold male machine mechanic who was taken to a local hospital on September 26 for two bullous, vesicular lesions with surrounding erythema, edema, and induration on the right forearm, which progressed to black eschars. The patient was treated for cellulitis with ceftriaxone followed by amoxicillin/clavulanate. The patient was reported to CDC on October 17 and serologic testing at CDC was reactive to B. anthracis. No biopsy was obtained. The patient's condition improved. On October 14, the second suspected case occurred in a 56-year-old female postal worker who sought medical care for fever, diarrhea, and vomiting at a local hospital. On October 19, the patient was admitted to the hospital with chills, dry cough, and pleuritic chest pain. A chest radiograph showed a small right infiltrate and bilateral effusions, but no evidence of a widened mediastinum. The next day, her respiratory status and pleural effusions worsened. A chest computerized tomography (CT) showed an enlarged mediastinal and cervical lymph nodes without parenchymal disease. The pleural fluid was positive for B. anthracis by PCR. Bilateral pleural effusions have complicated the patient's hospital course and she continues to require supplemental oxygen. On October 20, the postal facility was closed; the New Jersey Department of Health and Senior Services recommended that postal workers at both postal facilities initiate antimicrobial prophylaxis pending further epidemiologic and environmental investigation. Both facilities have been closed pending results of further environmental evaluation. Environmental sampling is being conducted at both postal facilities. In one facility, 13 of 23 samples from high-risk areas were preliminarily culture-positive for B. anthracis. Clean-up efforts are ongoing. Results of cultures from samples taken in the second facility and results from approximately 600 nasal swab cultures obtained from postal employees are pending.#
Since October 3, 2001, CDC and state and local public health authorities have been investigating cases of bioterrorism-related anthrax. This report updates previous findings, provides new information on case investigations in two additional areas, presents the susceptibility patterns of Bacillus anthracis isolates, and provides interim recommendations for managing potential threats and exposures and for treating anthrax.
As of October 24, investigations in the District of Columbia (DC), Florida, New Jersey, New York City (NYC), Maryland, Pennsylvania, and Virginia have identified 15 (11 confirmed and four suspected) cases of anthrax according to the CDC surveillance case definition (1 ). Seven of the 15 cases were inhalational anthrax and eight were cutaneous. Of the seven inhalational cases, five occurred in postal workers in New Jersey and DC, and one in a person who sorted and distributed mail at a media company in Florida. Two letters mailed to two different recipients in NYC and one letter mailed to a recipient in DC are known to have contained B. anthracis spores. Six cases were identified in employees of media companies; one was a 7-month-old infant who visited a media company; and eight cases are consistent with exposures along the postal route of letters known to be contaminated with B. anthracis spores in New Jersey and DC. Using molecular typing, analysis of B. anthracis isolates from cases in Florida, NYC, and DC indicated that the isolates are indistinguishable (2 ). Epidemiologic investigations and surveillance in other locations are continuing; no additional cases have been identified.

# Florida
As of October 24, investigations in Florida have identified two confirmed cases of inhalational anthrax in persons who worked at the same media company; no additional cases of disease have been identified since the last report (1 ). A pleural biopsy for the second confirmed patient was positive for B. anthracis by immunohistochemical (IHC) staining. In addition, a >4-fold increase in levels of serum antibody (IgG) to the protective antigen (PA) component of the anthrax toxin using enzyme-linked immunosorbant assay (ELISA) was demonstrated.
Environmental sampling of the work site revealed B. anthracis contamination and implicated one or more mailed letters or packages as the likely source of exposure. Several environmental specimens from regional and local postal centers that provided mail services to the work site were culture-positive for B. anthracis. Thirty postal workers anthrax, a chest radiograph and chest CT scan were performed that revealed mediastinal lymphadenopathy and a right middle lobe infiltrate. Antimicrobial therapy was initiated. Blood cultures grew B. anthracis within 18 hours. The patient is clinically stable and remains hospitalized.
On October 21, a third postal worker, a 55-year-old man, who worked at the same distribution center was admitted to the hospital with suspected inhalational anthrax. The patient had initially sought medical care at a physician's office on October 18 for 2 days of progressive fatigue, myalgias, and fever. The patient had a temperature of 102 F (38.9 C) and normal white blood cell count and was sent home. The patient returned to the ED on October 21 with persistent symptoms, including chills, vague chest tightness, and temperature of 102 F (38.9 C). Chest radiograph revealed right middle and lower lobe alveolar infiltrates and right hilar and peritracheal soft tissue fullness. Evaluation revealed hypoxia, leukocytosis, and hemoconcentration. Antimicrobial therapy was initiated, and the patient was mechanically ventilated. The patient's condition deteriorated, and he died on October 21. Blood cultures obtained on admission to the hospital grew grampositive bacilli, which were confirmed later as B. anthracis at CDC.
On October 22, a fourth postal worker, a 47-year-old man, who worked at the same distribution center was admitted to the hospital with suspected inhalational anthrax. The patient had initially presented to the ED on October 21 with complaints of 5 days of progressive fatigue, nausea, vomiting, and diarrhea, and syncope. The patient was afebrile and had orthostatic hypotension. A chest radiograph was obtained and reported to be normal. The patient received intravenous fluids and was discharged. He returned to the ED 26 hours later following another syncopal episode and persistent gastrointestinal complaints. The patient was afebrile, hypotensive, diaphoretic, and in respiratory distress. A second chest radiograph and a chest CT revealed mediastinal lymphadenopathy and bilateral pleural effusions. Subsequent review of the first chest radiograph revealed an ill-defined area of increased density in the right subhilar region. Laboratory evaluation revealed leukocytosis and hemoconcentration. Antimicrobial therapy was initiated, and the patient was mechanically ventilated. Peripheral blood smear demonstrated grampositive bacilli; blood cultures grew gram-positive bacilli within 18 hours and were confirmed as B. anthracis at CDC. The patient died on October 22.
On October 20, CDC and DCDOH initiated an investigation of the postal facility where the four patients were employed. Although no specific exposure event was identified, the contaminated tightly sealed letter that was mailed to the Senator's office was processed at this facility on October 12 before entering the Capitol mail distribution system. The postal facility was closed on October 21, and antimicrobial prophylaxis was recommended to employees working in proximity to the same mail sorting area of the first patient. In addition, visitors to nonpublic operations areas of this facility also were offered antimicrobial prophylaxis.
On October 22, because of concern about the potential for unrecognized aerosol exposures among postal workers, antimicrobial therapy was recommended for all workers and visitors to nonpublic areas in this postal facility. Subsequently, this recommendation has been extended to all postal workers in the DC area directly served by this postal facility pending results of ongoing epidemiologic and environmental investigation.
The first patient also worked at a second postal facility. On October 21, this facility also was closed. Antimicrobial prophylaxis also was recommended for workers at this facility pending further epidemiologic and environmental testing.

# Susceptibility Testing of B. anthracis Isolates
Antimicrobial susceptibility patterns were determined for 11 B. anthracis isolates associated with intentional exposures in Florida, NYC, and DC. Susceptibility breakpoints for interpreting minimum inhibitory concentration (MIC) results for B. anthracis have not been determined by the National Committee for Clinical Laboratory Standards (NCCLS); thus, breakpoints for staphylococci were used (3 ). All B. anthracis isolates were susceptible to ciprofloxacin (MIC<0.06 g/mL), doxycycline (MIC<0.03 g/mL), chloramphenicol (MIC=4 g/mL), clindamycin (MIC<0.5 g/mL), tetracycline (MIC=0.06 g/mL), rifampin (MIC<0.5 g/mL), and vancomycin (MIC=1-2 g/mL). Limited testing of imipenem suggests that these organisms are also susceptible to this agent (MIC<0.12 g/mL) and are likely susceptible to meropenem. Susceptibility of the isolates was considered intermediate to erythromycin (MIC=1 g/mL) and borderline susceptible to azithromycin (MIC=2 g/mL); clarithromycin was considered susceptible (MIC=0.25 g/mL).
B. anthracis isolates were susceptible to penicillin (MIC range: <0.06 ug/mL-0.12 g/ mL) and amoxicillin (MIC<0.06 g/mL); ceftriaxone (MIC=16) was considered intermediate. NCCLS has not defined either a B. anthracis or staphylococcal interpretive breakpoint for ceftriaxone results; thus, breakpoints for gram-negative organisms were used to interpret ceftriaxone results. These ceftriaxone MICs and additional laboratory data at CDC indicate the presence in B. anthracis isolates of a cephalosporinase, an enzyme that inhibits the antibacterial activity of cephalosporins such as ceftriaxone. Additional studies were performed with some of the B. anthracis isolates to identify other betalactamases, the general class of enzymes that inactivate penicillins, cephalosporins, and related drugs. These preliminary studies indicate the presence of a class B cephalosporinase and suggest that a penicillinase also may be present. These enzymes often are present in naturally occurring B. anthracis isolates.
This information is current as of October 24, 2001, 9 p.m. eastern daylight time. Intensive surveillance activities and environmental and case investigations are in progress to identify and treat all U.S. Postal Service workers and others at potential risk for anthrax. Surveillance also is being conducted to monitor adverse events associated with antimicrobial prophylaxis for anthrax. CDC and FBI are collaborating to accelerate all aspects of the investigation surrounding these events. Editorial Note: Bioterrorism attacks using B. anthracis spores sent through the mail have resulted in 15 anthrax cases and three deaths. The initial anthrax cases occurred among persons with known or suspected contact with opened letters contaminated with B. anthracis spores. Later, investigations identified four confirmed cases and one suspected case among postal workers who had no known contact with contaminated opened letters. This suggests that sealed envelopes contaminated with B. anthracis passing through the postal system may be the source of exposure. The number of contaminated envelopes passing through the postal system is not known. In addition, automated sorting could damage envelopes and release spores into postal environments; other circumstances that could contribute to the contamination of postal facility environments may be identified.
Because these cases are the result of intentional exposures, FBI and other law enforcement authorities are investigating these events as criminal acts and are working to identify and eliminate the source of these exposures. Until that occurs, the possibility of further exposure to B. anthracis and subsequent clinical illness exists. Clinicians and laboratorians should be vigilant for symptoms or laboratory findings that indicate B. anthracis infection, particularly among mail handlers. Information to guide healthcare providers and laboratorians is available at .

# Managing Threats
Letters containing B. anthracis spores have been sent to persons in NYC and DC. Prompt identification of a threat and institution of appropriate measures may prevent inhalational anthrax. To prevent exposure to B. anthracis and subsequent infection, suspicious letters or packages should be recognized and appropriate protective steps taken.
Characteristics of suspicious packages and letters include inappropriate or unusual labeling, strange return address or no return address, postmarks from a city or state different from the return address, excessive packaging material, and others. If a package appears suspicious, it should not be opened. The package should be handled as little as possible. The room should be vacated and secured promptly and appropriate security or law enforcement agencies promptly notified (Box 1).

# Box 1. Handling of Suspicious Packages or Envelopes
- Do not shake or empty the contents of a suspicious package or envelope.
- Do not carry the package or envelope, show it to others, or allow others to examine it. - Put the package or envelope on a stable surface; do not sniff, touch, taste, or look closely at it or any contents that may have spilled. - Alert others in the area about the suspicious package or envelope. Leave the area, close any doors, and take actions to prevent others from entering the area. If possible, shut off the ventilation system. - Wash hands with soap and water to prevent spreading potentially infectious material to face or skin. Seek additional instructions for exposed or potentially exposed persons. - If at work, notify a supervisor, a security officer, or a law enforcement official.
If at home, contact the local law enforcement agency. - If possible, create a list of persons who were in the room or area when this suspicious letter or package was recognized and a list of persons who also may have handled this package or letter. Give the list to both the local public health authorities and law enforcement officials.

# MMWR October 26, 2001
Update: Investigation of Bioterrorism-Related Anthrax -Continued

# Managing Exposures
Identification of a patient with anthrax or a confirmed exposure to B. anthracis should prompt an epidemiologic investigation. The highest priority is to identify at-risk persons and initiate appropriate interventions to protect them. The exposure circumstances are the most important factors that direct decisions about prophylaxis. Persons with an exposure or contact with an item or environment known, or suspected to be contaminated with B. anthracis-regardless of laboratory tests results-should be offered antimicrobial prophylaxis. Exposure or contact, not laboratory test results, is the basis for initiating such treatment. Culture of nasal swabs is used to detect anthrax spores. Nasal swabs can occasionally document exposure, but cannot rule out exposure to B. anthracis. As an adjunct to epidemiologic evaluations, nasal swabs may provide clues to help assess the exposure circumstances. In addition, rapid evaluation of contaminated powder, including particle size and characteristics, may prove useful in assessing the risk for inhalational anthrax.
CDC is working with U.S. Postal Service employees and managers on several strategies to address the risk for anthrax among workers involved in mail handling. These strategies include personal protective equipment for workers handling mail and engineering controls in mail facilities. Clinicians and laboratorians should be vigilant for symptoms or laboratory findings that indicate possible anthrax infection, particularly among workers involved in mail sorting and distribution. Information to guide health-care providers and laboratories is available at  (1 ).

# Antimicrobial Treatment
A high index of clinical suspicion and rapid administration of effective antimicrobial therapy is essential for prompt diagnosis and effective treatment of anthrax. Limited clinical experience is available and no controlled trials in humans have been performed to validate current treatment recommendations for inhalational anthrax. Based on studies in nonhuman primates and other animal and in vitro data, ciprofloxacin or doxycycline should be used for initial intravenous therapy until antimicrobial susceptibility results are known (Table 1). Because of the mortality associated with inhalational anthrax, two or more antimicrobial agents predicted to be effective are recommended; however, controlled studies to support a multiple drug approach are not available. Other agents with in vitro activity suggested for use in conjunction with ciprofloxacin or doxycycline include rifampin, vancomycin, imipenem, chloramphenicol, penicillin and ampicillin, clindamycin, and clarithromycin; but other than for penicillin, limited or no data exist regarding the use of these agents in the treatment of inhalational B. anthracis infection. Cephalosorins and trimethoprim-sulfamethoxazole should not be used for therapy. Regimens being used to treat patients described in this report include ciprofloxacin, rifampin, and vancomycin; and ciprofloxacin, rifampin, and clindamycin.
Penicillin is labelled for use to treat inhalational anthrax. However, preliminary data indicate the presence of constitutive and inducible beta-lactamases in the B. anthracis isolates from Florida, NYC, and DC. Thus, treatment of systemic B. anthracis infection using a penicillin alone (i.e., penicillin G and ampicillin) is not recommended. The B. anthracis genome sequence shows that this organism encodes two beta-lactamases: a penicillinase and a cephalosporinase. Data in the literature also show that some betalactamase negative B. anthracis strains for which the penicillin MICs are 0.06 g/mL increase to 64 g/mL and become beta-lactamase positive when exposed to semisynthetic penicillins (4 ). The frequency of this induction event is unknown. Although - For gastrointestinal and oropharyngeal anthrax, use regimens recommended for inhalational anthrax.
 Ciprofloxacin or doxycycline should be considered an essential part of first-line therapy for inhalational anthrax.  Steroids may be considered as an adjunct therapy for patients with severe edema and for meningitis based on experience with bacterial meningitis of other etiologies.  Other agents with in vitro activity include rifampin, vancomycin, penicillin, ampicillin, chloramphenicol, imipenem, clindamycin, and clarithromycin. Because of concerns of constitutive and inducible beta-lactamases in Bacillus anthracis, penicillin and ampicillin should not be used alone. Consultation with an infectious disease specialist is advised.  Initial therapy may be altered based on clinical course of the patient; one or two antimicrobial agents (e.g., ciprofloxacin or doxycycline) may be adequate as the patient improves.   If meningitis is suspected, doxycycline may be less optimal because of poor central nervous system penetration.   Because of the potential persistence of spores after an aerosol exposure, antimicrobial therapy should be continued for 60 days.   If intravenous ciprofloxacin is not available, oral ciprofloxacin may be acceptable because it is rapidly and well absorbed from the gastrointestinal tract with no substantial loss by first-pass metabolism. Maximum serum concentrations are attained 1-2 hours after oral dosing but may not be achieved if vomiting or ileus are present. * In children, ciprofloxacin dosage should not exceed 1 g/day.
   The American Academy of Pediatrics recommends treatment of young children with tetracyclines for serious infections (e.g., Rocky Mountain spotted fever).    Although tetracyclines are not recommended during pregnancy, their use may be indicated for life-threatening illness. Adverse effects on developing teeth and bones are dose related; therefore, doxycycline might be used for a short time (7-14 days) before 6 months of gestation.  - Cutaneous anthrax with signs of systemic involvement, extensive edema, or lesions on the head or neck require intravenous therapy, and a multidrug approach is recommended. Table 1.  Ciprofloxacin or doxycycline should be considered first-line therapy. Amoxicillin 500 mg po TID for adults or 80 mg/kg/day divided every 8 hours for children is an option for completion of therapy after clinical improvement. Oral amoxicillin dose is based on the need to achieve appropriate minimum inhibitory concentration levels.  Previous guidelines have suggested treating cutaneous anthrax for 7-10 days, but 60 days is recommended in the setting of this attack, given the likelihood of exposure to aerosolized B. anthracis (6 ).  The American Academy of Pediatrics recommends treatment of young children with tetracyclines for serious infections (e.g., Rocky Mountain spotted fever).  Although tetracyclines or ciprofloxacin are not recommended during pregnancy, their use may be indicated for life-threatening illness. Adverse effects on developing teeth and bones are dose related; therefore, doxycycline might be used for a short time (7-14 days) before 6 months of gestation.
amoxicillin/clavulanic acid is more active than amoxicillin alone against beta-lactamase, producing strains in vitro, the combination may not be clinically effective for inhalational anthrax where large numbers of organisms are likely to be present. Toxin-mediated morbidity is a major complication of systemic anthrax. Corticosteroids have been suggested as adjunct therapy for inhalational anthrax associated with extensive edema, respiratory compromise, and meningitis (5 ).
For cutaneous anthrax, ciprofloxacin and doxycycline also are first-line therapy (Table 2). As for inhalational disease, intravenous therapy with a multidrug regimen is recommended for cutaneous anthrax with signs of systemic involvement, for extensive edema, or for lesions on the head and neck (Table 2). In cutaneous anthrax, antimicrobial treatment may render lesions culture negative in 24 hours, although progression to eschar formation still occurs (5 ). Some experts recommend that corticosteroids be considered for extensive edema or swelling of the head and neck region associated with cutaneous anthrax. Cutaneous anthrax is typically treated for 7-10 days; however, in this bioterrorism attack, the risk for simultaneous aerosol exposure appears to be high. Although infection may produce an effective immune response, a potential for reactivation of latent infection may exist. Therefore, persons with cutaneous anthrax associated with this attack should be treated for 60 days.
Prophylaxis for inhalational anthrax exposure has been addressed in a previous report (1 ) and indicates the use of either ciprofloxacin or doxycycline as first line agents. High-dose penicillin (e.g., amoxicillin or penicillin VK) may be an option for antimicrobial prophylaxis when ciprofloxacin or doxycycline are contraindicated. The likelihood of beta-lactamase induction events that would increase the penicillin MIC is lower when only small numbers of vegetative cells are present, such as during antimicrobial prophylaxis.
All medications may have undesirable side effects and allergic reactions may result from any medication. Clinicians prescribing these medications should be aware of their side effects and consult an infectious disease specialist as needed. Patients should be urged to inform their health-care provider of any adverse event.
This is the first bioterrorism-related anthrax attack in the United States, and the public health ramifications of this attack continue to evolve. Additional updates and recommendations will be published in MMWR.

# Methicillin-Resistant Staphylococcus aureus Skin or Soft Tissue Infections in a State Prison -Mississippi, 2000
On October 25, 2000, the Mississippi State Department of Health (MSDH) notified CDC that, since November 1999, 31 inmates had acquired methicillin-resistant Staphylococcus aureus (MRSA) skin or soft tissue infections at a state prison. During November 1998-October 1999, no MRSA infections had been reported at the prison, which houses approximately 1,200 female and 1,800 male inmates. This report summarizes the case investigation and the nasal culture prevalence survey conducted by MSDH and CDC during November 2000. Findings indicate that MRSA infections were transmitted person-to-person within the prison, and that the number of asymptomatic carriers was unexpectedly high for a nonhealth-care setting. Correctional facilities can reduce the increasing prevalence of MRSA disease by identifying and appropriately treating infected persons and by instituting prevention measures.
A case of MRSA infection was defined as a skin or soft tissue lesion occurring in a state prison inmate with symptoms (e.g., pus, pain, warmth, or tenderness) and with MRSA cultured from the site of infection during November 1999-November 2000. Cases were identified by interviews with physicians and inmates and a review of the prison's medical, laboratory, and pharmacy records. Fifty-nine inmates had an illness that met  the case definition (Figure 1); 46 (78%) were women, and the median age was 33 years (range: 19-70 years). The median length of incarceration was 397 days (range: 3-3,717 days). Records of 45 (76%) infected inmates were reviewed. Three (7%) had been hospitalized during the year preceding infection. Twenty-six (58%) had infections on the legs and seven (16%) on the arms. Fifteen (33%) were diagnosed with furuncles, 12 (27%) with skin abscesses, and 11 (24%) with open wounds; 21 (47%) had cellulitis, and two (4%) had systemic infections requiring hospitalization. Infections resolved after a median of 3 weeks (range: 1-36 weeks). Systemic antimicrobials were used to treat 44 (98%) infected inmates, 35 (78%) received topical antimicrobials, six (13%) required incision and drainage, and wound dressing was prescribed for 21 (47%). Nineteen (90%) of the 21 infected inmates with wound dressings changed their dressings themselves. During interviews, 15 (33%) infected inmates reported helping or being helped by other inmates with wound care or dressing changes. Twenty-six (58%) reported lancing their own boils or other inmates' boils with fingernails or tweezers; 40 (89%) shared personal items (e.g., linen, pillows, clothing, and tweezers) that potentially were contaminated by wound drainage.
To assess the extent of MRSA carriage among the inmates, swab specimens of both anterior nares were collected from all female and a one third systematic sample of male inmates. Of 1,757 inmates sampled, 86 (4.9%) were MRSA carriers. More women (73 of 1,241 ) were carriers than men (13 of 516 ) (p=0.003), and inmates who had been incarcerated for >60 days were more likely to be carriers (84 of 1,565 ) than those who had served less time (one of 142 ) (p=0.01).
Of the 59 infection-associated isolates, 41 (69%) were tested and genotyped at CDC. All 41 isolates were confirmed as MRSA and 40 (98%) were susceptible to gentamicin, rifampin, trimethoprim-sulfamethoxazole, clindamycin, vancomycin, and chloramphenicol; three (7%) were resistant to levofloxacin. Pulsed-field gel electrophoresis of isolates revealed that three MRSA strains predominated: genotype A (24 ), genotype B (seven ), and genotype C (four ).
During December 2000, CDC and MSDH provided the Mississippi State Department of Corrections and the prison with control measures such as optimizing antimicrobial treatment of infected inmates, reinforcing infection control practices (e.g., implementing Standard Precautions  at prison clinics, educating inmates in personal hygiene and wound care), using antibacterial soap, and establishing an MRSA skin infection surveillance system. Editorial Note: S. aureus is an important and common pathogen in humans. It is found in the nose or on the skin of many healthy, asymptomatic persons (i.e., carriers) and can cause infections with clinical manifestations ranging from pustules to sepsis and death. Most transmission occurs through the contaminated hands of a person infected with or carrying S. aureus. MRSA infections frequently are encountered in health-care settings (2 ). Since the 1960s, treatment of these infections has become more difficult because S. aureus has progressively acquired resistance to previously effective antimicrobial agents (2 ). In 1999, 2,538 (53.5%) of 4,744 intensive care unit patients with hospitalacquired S. aureus-associated infection had MRSA (3 ). Less information is available on long-term-care facilities, where prevalence of MRSA carriage may range from zero to 33% of the residents (4 ).
Risk factors for infection with MRSA in health-care settings include prolonged hospital stay, exposure to multiple or prolonged broad-spectrum antimicrobial therapy, stay in an intensive care or burn unit, proximity to patients colonized or infected with MRSA, use of invasive devices, surgical procedures, underlying illnesses, and MRSA nasal carriage (5 ).
Although community-onset MRSA infections have been reported recently (6 ), little is known about their epidemiology or prevalence of carriage. Community outbreaks have occurred among injection-drug users; aboriginals in Canada, New Zealand, and Australia; Native Americans/Alaska Natives in the United States; and players of close-contact

# MMWR October 26, 2001
Methicillin-Resistant Staphylococcus aureus -Continued sports (6 ). Reported most commonly have been uncomplicated skin infections; however, community-acquired MRSA infections can be severe. Four deaths from communityacquired MRSA in children were reported in Minnesota and North Dakota in 1999 (7 ). Disease transmission can occur easily among inmates at correctional facilities. In 1999, approximately two million persons were incarcerated in the United States (8 ). Skin or soft tissue infections are recognized problems in these facilities (9 ). MRSA disease in prisons can be controlled or prevented using several approaches. First, severe skin disease or treatment failures of presumed S. aureus skin infection should be evaluated with appropriate cultures or other diagnostic tests. Efforts to monitor the etiology of skin disease should be linked to these data to determine whether MRSA is a problem in the facility. MRSA outbreaks can be reported to CDC (telephone  893-0485) through state departments of corrections and state health departments. Second, optimal treatment of MRSA disease should be based on the infecting organism's antimicrobial susceptibility result and, when available, input by infectious disease expertise. Third, close contact among inmates may place them at increased risk for transmission of skincolonizing or skin-infecting organisms. To prevent skin disease, all inmates should practice good personal hygiene, including daily showers. Inmates should avoid touching wounds or drainage of others and should have access to sinks and plain soap (in this setting, the usefulness of antibacterial soap is unknown). Hands should be washed with soap as soon as possible after touching wounds or dressings. Personnel that provide wound care should follow Standard Precautions (1 ).  (4 ). This report describes an investigation of S. sonnei cases that occurred among MSM in San Francisco during May-December 2000. Following efforts to heighten awareness, the number of cases has declined, but new cases continue to occur at low levels in this risk group (Figure 1). The increased incidence of sexually transmitted Shigella and other sexually transmitted diseases (STDs) in MSM require renewed and innovative prevention efforts.
During June-December 2000, 230 cases of culture-confirmed- S. sonnei infection were reported to the San Francisco Department of Public Health; an average of 21 cases (range: 13-29 cases) occurred during the same period from 1996 to 1999. Based on data obtained from 230 reported cases, the median age was 39 years (range: 16-77 years) and 211 (92%) patients were males. Of 199 males for whom information was available, 141 (71%) were non-Hispanic whites, 159 (80%) were residents of predominantly gay neighborhoods, and 121 (61%) were self-reported MSM. Sexual behavior was unknown for 62 (31%) patients, and 16 (8%) were self-reported heterosexuals. On the basis of denominator data obtained from the annual San Francisco HIV/AIDS epidemiology report, the rate of S. sonnei infection among MSM was 259 per 100,000 population. The rate among all other groups, including women and heterosexual men, was 16 (5 ). Among persons aged >18 years with S. sonnei and symptom onset during May-December 2000, 106 were selected randomly for telephone interview; 35 (33%) could not be contacted and four (4%) refused to participate. Of the 67 (63%) who agreed to participate, 64 (96%) were male. Among the 64 male respondents, 62 (97%) were MSM, 42 (66%) were college graduates, and 29 (46%) had an annual income >$45,000. Of the respondents, 49 (78%) had health insurance coverage, 45 (70%) thought they became ill from a sexual partner, and 35 (55%) reported concurrent infection with human immunodeficiency virus (HIV).
The median duration of symptoms for male respondents was 7 days (range: 2-90 days); 62 (97%) reported diarrhea, 50 (78%) abdominal cramps, 49 (77%) fever, 47 (73%) weight loss, and 20 (31%) blood in stool.
In the week before illness, 50 (78%) of the 64 males reported being sexually active, including 34 (53%) who had multiple sex partners; 32 (50%) answered "yes" to, "The week before your illness did you put your tongue in a partner's anus?" Forty-seven (73%) answered "yes" to, "The week before your illness did you have a penis in your mouth?"
Of the 14 patients who reported sexual activity during the week of or the week following illness, three (21%) answered "yes" to, "During  your illness did you have a tongue in your anus?" All 14 persons who were sexually active during and after illness reported diarrhea (duration: 3-23 days) for which they were prescribed antibiotics.
Local response to the outbreak included a press release, development of an Internet web site, and a media campaign with newspaper and Internet articles for the gay community. Approximately 2,000 notices were mailed to community agencies and providers, 10 presentations were conducted for community agencies, and 4,000 health alerts were distributed through a mass mailing to 40 acquired immunodeficiency syndrome-related agencies and their clients, several large gay and lesbian fairs, bars, sex clubs, and the city STD clinic.
Free Shigella screening was offered for 1 month at the city STD clinic. Of 119 patients screened, five reported having diarrhea at presentation to the STD clinic. Two of the five had S. sonnei isolated from their rectal swab samples; no Shigella species were isolated from the 114 remaining clients.
A convenience sample of S. sonnei from outbreak-related patients and controls (women and children with S. sonnei infection in the outbreak period and region) was subtyped by pulsed-field gel electrophoresis (PFGE). Of 26 outbreak-related isolates, 23 (88%) shared one of two closely related patterns, and only one (12%) of eight isolates from controls had a similar PFGE patterns.
Of 20 randomly selected isolates from outbreak-related patients, 19 were resistant to trimethoprim-sulfamethoxazole, tetracycline, ampicillin, sulfisoxazole, and streptomycin. All isolates were susceptible to ciprofloxacin, nalidixic acid, and ceftriaxone. Approximately half of the patients in this report were infected with HIV compared with an estimated prevalence of 20% among MSM in San Francisco (7 ), suggesting that MSM with HIV infection are more likely to participate in sexual behaviors that place them at risk for shigellosis. Standard HIV management includes stool bacteria cultures of persons with diarrhea. However, HIV-infected persons with shigellosis might have more severe illness (8 ) leading to more frequent diagnosis and reporting.
The findings in this report are subject to at least two limitations. First, approximately a third of the selected cases could not be contacted, and those who were might have had difficulty accurately recalling events that occurred up to 6 months preceding the interview. Second, the magnitude of this outbreak probably was underestimated because reporting shigellosis in California is required of physicians but not of laboratories, and many cases probably were undiagnosed and unreported.
Because most patients in this outbreak were sexually active with multiple partners, the potential for ongoing transmission is high. In San Francisco and other communities with high rates of shigellosis in adult men, clinicians should obtain stool cultures and sexual orientation data from men with diarrhea and report suspected cases of shigellosis to the health department. Appropriate antimicrobial therapy will decrease the duration, transmission, and severity of symptoms and should be prescribed based on the severity of illness or the need to protect close contacts. Patients in certain occupations (i.e., foodhandlers, child-care providers, and health-care workers) and children who attend child care often are required to have a negative stool culture documented following treatment. The incubation period of shigellosis is 1-4 days, and shigellae are shed in stool from several days to several weeks after illness. Persons who receive appropriate antimicrobial therapy will be culture negative at 72 hours (9 ).
Patients with shigellosis should be counseled to abstain from sexual behavior that is likely to transmit infection for at least 3 days after starting an appropriate course of antimicrobial therapy (9 ). Because antimicrobial resistance is common, in cases in which antimicrobial susceptibility data are not available, patients should be counseled on abstaining from high-risk sexual behavior until at least one negative posttreatment stool culture is obtained. Patients also should be counseled on methods to avoid or reduce the risk for sexual transmission of enteric infections such as Shigella and hepatitis A, should be educated to avoid sexual practices that might result in fecal-oral transmission, and should be advised to wash with soap and water the perianal/perineal area, other body parts, and sex toys before and after sexual activity.

# Weekly Update: West Nile Virus Activity -United States, October 17-23, 2001
The following report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET and verified by states and other jurisdictions as of October 23, 2001.
During the week of October 17-23, six human cases of WNV encephalitis or meningitis were reported in Pennsylvania (three), New Jersey (two), and Florida (one). During the same period, WNV infections were reported in 101 crows, 45 other birds, and 26 horses. A total of 31 WNV-positive mosquito pools were reported in five states (Connecticut, Florida, Georgia, New York, and Ohio).
During 2001, 37 human cases of WNV encephalitis or meningitis have been reported in Florida (10), Maryland (six), New York (six), New Jersey (six), Connecticut (five), Pennsylvania (three), and Georgia (one); one death occurred in Georgia. Among these 37 cases, 20 (54%) were in males, the median age was 69 years (range: 36-81 years), and dates of illness onset ranged from July 13 to October 7. A total of 3,796 crows and 1,394 other birds with WNV infection were reported from 25 states and the District of Columbia (Figure 1); 151 WNV infections in other animals (all horses) were reported from 11 states (Alabama, Connecticut, Florida, Georgia, Kentucky, Louisiana, Massachusetts, Mississippi, New York, Pennsylvania, and Virginia); and 725 WNV-positive mosquito pools were reported from 14 states (Connecticut, Florida, Georgia, Illinois, Kentucky, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, and Rhode Island).
Additional information about WNV activity is available at  and . October 21-27 is National Lead Poisoning Prevention Week (NLPPW), and this year's theme is "Treat Yourself to Lead-Safe Living: Harvest the Rewards." Childhood lead poisoning is considered the most preventable environmental disease of young children, but approximately one million children have elevated blood lead levels. One of the national health objectives for 2010 is to eliminate childhood lead poisoning in the United States (objective 8-11) (1 ). The goal of NLPPW is 1) to raise awareness about this serious health issue and the importance of screening at-risk children at aged 1-2 years and children aged 3-5 years who have not been screened previously and 2) to urge persons to take precautions to minimize exposure to lead.
In commemoration of NLPPW, events such as state proclamations, free screenings, lead-awareness community events, and educational campaigns will be conducted nationwide. CDC, the Environmental Protection Agency, and the U.S. Department of Housing and Urban Development are collaborating to coordinate activities and offer assistance to campaigns at the local level. Additional information about NLPPW activities is available from state or local health departments.
Additional information about preventing childhood lead poisoning is available at http: //cdc.gov/nceh/lead or from the National Lead Information Center, telephone (800) 424-LEAD ( 424-5323).
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