German doctors have published a case report of a man who became infected with HIV after an episode of unprotected insertive anal sex, and despite receiving a course of post-exposure prophylaxis. The report is published in the February 20th edition of the AIDS.
The case involved a man who had tested negative for HIV in 1999. In late 2001 he started a sexual relationship with a man known to be HIV-positive. At this time, the HIV-positive individual was on a treatment break from his antiretroviral therapy and had a viral load of 20,000 copies/ml.
In December 2001 both men requested HIV risk counselling and post-exposure prophylaxis after a single brief episode of unprotected anal sex in which the HIV-negative man was insertive.
A baseline HIV antibody test was negative, and the man was provided with a post-exposure prophylaxis (PEP) regimen consisting of d4T, ddI and Kaletra. The man took PEP for four weeks.
Two weeks after the completion of PEP, the man developed symptoms of primary HIV infection including a rash and high fever. The man’s viral load was tested and was found to be 750,000 copies/ml and his CD4 cell count was 400 cells/mm3. Two weeks later the man tested HIV-positive.
Because of symptoms, the man was started on a HAART regimen consisting of 3TC, abacavir and efavirenz, leading to an increase in his CD4 cell count and an undetectable viral load within twelve weeks.
The investigators were in no doubt that the man was infected with HIV by his partner after testing revealed that the men shared a closely related strain of HIV.
The investigators speculate that the failure of PEP to prevent infection with HIV could have been related to the possible mode of HIV transmission. They explain, “The first cells to come into contact with HIV during insertive anal intercourse would be Langerhans cells in the foreskin and penile mucosa. HIV can be internalized into these cells, retaining its infectivity for an extended period of time and remaining protected from the effects of antiretroviral drugs.” When the course of PEP ended, surviving virus in these cells could start replicating, leading to infection. However, they acknowledge that it is possible that the man became infected with HIV after the cessation of PEP, from an unreported risk activity, or had been in the window period of HIV infection when PEP was prescribed.
Further information on this website
Treatment to prevent infection – post exposure prophylaxis - overview
Cordes C et al. HIV transmission despite post-exposure prophylaxis after non-occupational exposure. AIDS 18: 582 - 584, 2004.