By Stan Deresinski, MD, FACP, clinical professor of medicine, Stanford University and associate chief of infectious diseases, Santa Clara Valley Medical Center, Santa Clara, California.
The Centers for Disease Control published its first recommendations for management of exposure to human immunodeficiency virus (HIV) in the occupational setting in 1990, at a time when the only available antiretroviral was zidvudine.1 It first addressed the issue of nonoccupational exposure in print in 1998, at which time, however, it concluded that the available evidence for or against post-exposure prophylaxis (PEP) in this setting was inadequate to allow for recommendations applicable to the United States.2 Since then, a great deal of information has become available.
Data from animal and human studies provide clear evidence that the initiation of antiretroviral therapy within 48 to 72 hours after nonoccupational exposure to HIV is likely to reduce the risk of transmission. This study considers a nonoccupational exposure to be “any direct mucosal, percutaneous, or intravenous contact with potentially infectious body fluids that occurs outside perinatal or occupational situations (e.g., health care, sanitation, public safety, or laboratory employment). Potentially infectious body fluids are blood, semen, vaginal secretions, rectal secretions, breast milk, or other body fluid that is contaminated with visible blood.”3
The CDC recommends prompt institution of PEP within 72 hours after such exposures when the source is known to be HIV infected and the exposure is substantial (See Figure 1). The estimated risks of various exposures are listed in Table 1.
Table 1. Estimated Per-Act Risk for Acquisition of HIV
In cases in which the HIV status of the source is unknown, PEP is not recommended, but the CDC encourages clinicians and patients “to weigh the risks and benefits on a case-by-case basis.” In addition, in instances in which patients seek care more than 72 hours after substantial exposure, the CDC urges clinicians to consider prescribing PEP “if, in their judgment, the diminished potential benefit of PEP outweighs the potential risk for adverse events from antiretroviral medications.” In any case, individuals seeking evaluation should be provided counseling in risk-reduction and any other intervention services that are indicated to reduce the likelihood of future exposures.
The CDC recommends, as preferred PEP regimens, one of the following:
- Efavirenz plus either lamivudine or emtricitabine plus either zidovudine or tenofovir.
- Lopinavir/ritonavir (Kaletra®) plus either lamivudine or emtricitabine plus zidovudine. PEP should be administered for 28 days.
The potential teratogenicity of efavirenz precludes its use in pregnancy and in women of childbearing age at risk of pregnancy. When efavirenz is prescribed to women of childbearing potential, they should be instructed about the need to avoid pregnancy.
In practice, decisions concerning the level of risk are often quite difficult. In my opinion, a good practice in such circumstances, is to initiate PEP and then reevaluate. PEP always can be discontinued if a conclusion is reached that the risk of exposure was negligible.
References
1. The Centers for Disease Control. Public Health Service statement on management of occupational exposure to human immunodeficiency virus, including considerations regarding zidovudine postexposure use. MMWR 1990;39:1-14.
2. The Centers for Disease Control. Management of Possible Sexual, Injecting Drug-Use, or Other Nonoccupational Exposure to HIV, Including Considerations Related to Antiretroviral Therapy: Public Health Service Statement. MMWR 1998;47:1-14.
3. Smith, et al. Antiretroviral postexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV in the United States. MMWR 2005; 54(RR02):1-20.
The Centers for Disease Control published its first recommendations for management of exposure to human immunodeficiency virus in the occupational setting in 1990, at a time when the only available antiretroviral was zidvudine. Since then, a great deal of information has become available.
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