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Herpes Therapy Doesn't Bar HIV Transmission
MedPage Today
January 20, 2010
Action Points
* Explain to interested patients that some evidence originally suggested that treating herpes simplex-2 might reduce the risk of HIV transmission between discordant couples (where one person was HIV positive and the partner wasn't).
* Note, however, that this study -- along with some earlier trials -- now appears to rule that out.
Treating herpes has no effect on the transmission of HIV among discordant couples, researchers said.
The lack of efficacy was found in a large, randomized clinical trial despite significant reductions in HIV viral load among those treated for herpes simplex-2 (HSV-2), according to Connie Celum, MD, of the University of Washington, and colleagues.
Researchers will have to look for new ways to prevent transmission among discordant couples (in which one partner has HIV and the other does not), Celum and colleagues concluded online in the New England Journal of Medicine.
The study comes after earlier trials also showed that treating HSV-2 with the antiviral acyclovir (Zovirax) did not lower the risk of getting HIV.
The trials -- and the current study -- had their origins in epidemiological and laboratory observations that having an HSV-2 infection increased the risk of contracting HIV.
Researchers reasoned that a converse effect might also be true -- treating HSV-2 in HIV-negative people might reduce their risk of infection.
The reasoning was bolstered by clinical trials showing that treating HSV-2 in HIV-positive people lowered their viral load.
In the current study, that effect also occurred. HIV-positive volunteers treated with acyclovir saw, on average, a reduction in plasma concentration of HIV by 0.25 log10 copies per milliliter compared with members of the placebo group. The difference was significant at P<0.001.
But transmission among the couples was not affected, implying that a greater reduction in viral load is needed, the researchers said.
The study, randomized and placebo-controlled, included 3,408 couples in Africa in which only one of the partners had HIV (but was not taking antiretroviral therapy) and also had an HSV-2 infection.
The outcome was first reported at the Cape Town meeting of the International AIDS Society last year.
The primary outcome was transmission between partners, verified by genetic sequencing of the virus.
Transmission between partners was verified in 84 of the 132 recorded cases of transmission, the researchers said, and they were evenly divided -- 41 among those getting the drug and 43 in the placebo group.
On the other hand, the use of the drug reduced the occurrence of herpes lesions by 73%, which was significant at P<0.001.
The reduction of herpes lesions suggests that the drug was being used, the researchers said, and therefore that the lack of efficacy against HIV was not a result of nonadherence to acyclovir.
Overall, the rate of HIV transmission in the study was 2.7 cases per 100 person-years, markedly lower than earlier observations. The researchers attributed that to such interventions as monthly counseling on risk reduction and free condoms.
The study had support from the Bill and Melinda Gates Foundation, as well as the University of Washington, the National Institute of Allergy and Infectious Diseases, Gen-Probe, and the National Institute of Mental Health.
Celum reported financial links with GlaxoSmithKline and several other authors reported links with various pharamceutical companies.
FREE Primary source: New England Journal of Medicine
Source reference:
Celum C, et al "Acyclovir and transmission of HIV-1 from persons infected with HIV-1 and HSV-2" N Engl J Med 2010.
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