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Am Fam Physician. 2010;81(5):649

Background: Postexposure prophylaxis for human immunodeficiency virus (HIV) infection is standard for occupational exposures (e.g., needlestick) in which it can reduce infection rates by more than 80 percent. Postexposure prophylaxis may also be useful for nonoccupational HIV exposures (e.g., sexual contact, intravenous drug use). Landovitz and Currier reviewed available guidelines from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), and summarized the current recommendations.

Recommendations: The decision to administer postexposure prophylaxis is based on the characteristics of the exposure and the source patient. Risk of HIV transmission varies widely depending on the type of exposure (see accompanying table). Both the exposed patient and source patient should have their HIV status documented at baseline by an enzyme-linked immunosorbent assay (ELISA) test. HIV viral load testing in asymptomatic patients is not recommended because of concerns of false-positive results and cost. The exposed patient should also have baseline testing for hepatitis B surface antigen, hepatitis B virus surface antibodies, hepatitis C virus antibodies, and creatinine and liver function, in addition to a complete blood count. Testing for syphilis, gonorrhea, and chlamydia should also be performed in cases of sexual exposure. HIV testing should be repeated at four to six weeks, three months, and six months after exposure. Patients who have been exposed to HIV should use condoms during sexual contact and avoid sharing razors and toothbrushes until negative test results are documented at six months.

Type of exposureEstimated risk per episode* (95% confidence interval)
Percutaneous (e.g., needlestick)0.3% (0.2 to 0.5)
Splash contact to mucous membranes0.09% (0.006 to 0.5)
Receptive anal intercourse1 to 30%
Insertive anal or receptive vaginal intercourse0.1 to 10.0%
Insertive vaginal intercourse0.1 to 1.0%
Injection drug use with needle sharing0.67% per needle-sharing contact

HIV postexposure prophylaxis should be offered to the exposed patient if the source patient is known to be HIV-positive. A negative HIV test in the source patient usually makes postexposure prophylaxis unnecessary, but it should still be considered if HIV status is unknown or if he or she belongs to a high-risk subgroup (i.e., men who have sex with men, sex workers, injection drug users, persons with a history of incarceration, persons who come from a country in which the prevalence of HIV infection is more than 1 percent, or persons with a sex partner belonging to one of these groups). Sexual assault victims should also be offered postexposure prophylaxis.

Treatment should be initiated as soon as possible after a potential exposure (preferably within 36 hours) and should be continued for 28 days. Weekly contact by telephone or e-mail may improve adherence to the treatment regimen, which is estimated to be only 70 to 80 percent. The optimal postexposure prophylaxis regimen is unclear, although several regimens are available.

Conclusion: Further guidelines for occupational and non-occupational exposure are available from the CDC and WHO. Physicians can also receive 24-hour postexposure prophylaxis advice from the National Clinicians' Post-Exposure Prophylaxis Hotline at 1-888-448-4911.

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