for managing patients with suspected viral hemorrhagic fever (VHF) who are admitted to U.S. hospitals. This document provides additional epidemiologic data on the transmission of VHF and updated recommendations on infection control precautions during patient care, environmental infection control procedures, case reporting, specimen handling and testing, handling of human remains, and post-exposure management. The terms and categories of isolation in this document are based on those outlined in the Guideline for Isolation Precautions in Hospitals (www.cdc.gov /ncidod/hip/ISOLAT/Isolat.htm l). These interim recommendations will be updated as additional information becomes available.

# Transmission Risk
In Africa, transmission of VHF in healthcare settings has been associated with reuse of contaminated needles and syringes and with provision of patient care without appropriate barrier precautions to prevent exposure to virus-containing blood and other body fluids (including vomitus, urine, and stool) (1-3). The transmission risks associated with various body fluids have not been well defined because most caregivers who have acquired infection had contacts with multiple fluids.
The risk for person-to-person transmission of hemorrhagic fever viruses is greatest during the latter stages of illness when virus loads are highest; latter stages of illness are characterized by vomiting, diarrhea, shock, and, in less than half of infected patients, hemorrhage. No VHF infection has been reported in persons whose contact with an infected person occurred only during the incubation period (i.e., before onset of fever). The incubation period for VHF ranges from 2 days to 3 weeks, depending on the viral agent (1). There are reports of Ebola virus transmission occurring within a few days after onset of fever; however, the presence of other symptoms in the source patients and the level of exposure to body fluids among secondary cases are unknown in these instances (CDC, unpublished data, 1995). In studies involving three monkeys experimentally infected with Ebola virus (Reston strain), fever and other systemic signs of illness preceded detection of infectious virus in the animals' pharynx by 2-4 days, in the conjunctivae and on anal swabs by 5-6 days, and in the nares by 5-10 days (8).
In studies involving nonhuman primates, monkeys could be infected by mechanically generated small-particle aerosols (4-7), but epidemiologic studies in humans do not indicate that VHF is readily transmitted from person to person by the airborne route (1,2). Airborne transmission was considered as a possible explanation for a hospital-associated cluster of Lassa fever infections in which the index patient had severe pulmonary involvement, but the mode of transmission for that outbreak was not determined (3). Although unproven, airborne transmission of VHF is a hypothetical possibility during procedures that may generate aerosols.

# Case Reporting and Specimen Testing
All suspected cases of VHF should be reported immediately to local and state health departments and to CDC (Special Pathogens Branch, 404 639-1115). Consult the Special Pathogens Branch before obtaining or sending specimens to CDC for confirmatory testing. State health departments should also be notified before sending specimens to CDC. For links to state health departments visit the "Information Networks and Other Information Sources" page on the CDC Web site www.cdc.gov/doc.do/id/0900f3ec80226c7a.

# Risk Categories
VHF should be suspected in febrile persons who, within 3 weeks before onset of fever, have either 1) traveled in the specific local area of a country where VHF has recently occurred; 2) had direct unprotected contact with blood, other body fluids, secretions, or excretions of a person or animal with VHF; or 3) had a possible exposure when working in a laboratory that handles hemorrhagic fever viruses. The likelihood of acquiring VHF is considered low in persons who do not meet any of these criteria. Even following travel to areas where VHF has occurred, persons with fever are more likely to have infectious diseases other than VHF (e.g., common respiratory viruses, endemic infections such as malaria or typhoid fever). Clinicians should promptly evaluate and treat patients for these more common infections while awaiting confirmation of a VHF diagnosis.

# Infection Control Precautions
The following recommendations should be followed when caring for persons with suspected VHF.

# Specimen Handling
- Alert laboratory staff to the nature of the specimens prior to sending them to the clinical laboratory. Specimens should remain in the custody of designated laboratory personnel until testing is completed.
Due to the potential risks associated with handling infectious materials, laboratory testing should be limited to the minimum necessary for essential diagnostic evaluation and patient care.
- While obtaining clinical laboratory specimens from the patient, use infection control precautions for patient care outlined in this document. Place specimens in sealed plastic bags, then transport them in a clearly labeled, durable, leak-proof container directly to the specimen handling area of the laboratory. Care should be taken not to contaminate the external surfaces of containers.
- Process clinical specimens in a class II biological safety cabinet following biosafety level 3 practices. If possible, pretreat serum used in laboratory tests with the combination of heat-inactivation at 56 C and polyethylene glycol p-tert-octylphenyl ether (Triton() X-100)*; treatment with 10 uL of 10% Triton() X-100 per 1 mL of serum for 1 hour reduces the titer of hemorrhagic fever viruses in serum, although 100% efficacy in inactivating these viruses should not be assumed. For tests in which the validity is affected by the presence of a detergent in the serum, heat inactivation alone may be of some benefit in reducing infectivity (9). - Blood smears (e.g., for malaria) are not infectious for VHF after fixation in solvents.

# Handling of Human Remains
If the patient dies, handling of the body should be minimized. The remains should not be embalmed. Remains should be wrapped in sealed leak-proof material and cremated or buried promptly in a sealed casket. If an autopsy is necessary, the state health department and CDC should be consulted regarding appropriate precautions.

# Management of Exposures
Persons with percutaneous or mucocutaneous exposures to blood, body fluids, secretions, or excretions from a patient with suspected VHF should immediately wash the affected skin surfaces with soap and water. Mucous membranes (e.g., conjunctiva) should be irrigated with copious amounts of water or eyewash solution. Exposed persons should receive medical evaluation and follow-up care, including fever monitoring twice daily for 21 days after exposure. Consultation with an infectious diseases expert is recommended for exposed persons who develop fever within 21 days of exposure. *Use of trade names and commercial sources is for identification only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services.