Treatment with zidovudine after occupational exposure to HIV decreased the chance of HIV infection by 79% in a case–control study . The study led to recommendations that prophylaxis should be considered for persons with HIV sexual exposure [2,3]. Failures of zidovudine postexposure prophylaxis (PEP) have, however, been reported among healthcare workers . We report here a case of failure of PEP after sexual exposure to HIV.
A 20-year-old woman presented to the hospital in October 1999 because she had had receptive vaginal intercourse with an HIV-infected man 70 h earlier. The man had been off antiretroviral therapy for the past 2 years. An initial HIV antibody test (enzyme-linked immunosorbent assay) was negative. Treatment combining zidovudine, lamivudine and nelfinavir was prescribed for 4 weeks. The woman did not come to the follow-up visits. In December 1999, she developed a probable acute retroviral illness with unexplained fever, cervical lymph nodes and skin eruption of the trunk, which resolved spontaneously within 5 days. In February 2000, she presented again at the hospital, and HIV-1 infection was diagnosed with two positive enzyme-linked immunosorbent assay tests and a typical Western blot pattern. The woman denied any new exposure to HIV and indicated that she had taken the treatment for 4 weeks as prescribed. The plasma HIV-1 viral load was 69 200 copies/ml (Amplicor HIV-1 1.5 Monitor, Roche Molecular Systems, Branchburg, NJ, USA). A genotypic analysis of plasma HIV-1 failed to detect any mutation in the reverse transcriptase or protease genes.
This observation is the first documented failure of PEP after non-occupational HIV exposure. This failure could be explained in different ways: (i) the delay between exposure and the beginning of prophylaxis, 70 h, was perhaps too long, although it is the cut-off suggested for occupational exposure ; (ii) antiretroviral resistance of the contaminating viral strain; (iii) poor adherence to therapy; and (iv) a new exposure to HIV.
This observation emphasizes the importance of close follow-up after HIV exposure. It is also a reminder that PEP is not always effective, and that behavioural risk reduction remains essential to prevent HIV infection.
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