Current WHO treatment access criteria may have limited impact on onward transmission of HIV

A study involving HIV-positive women in Kenya suggests that providing antiretroviral therapy to individuals with advanced HIV disease may only have a limited impact on HIV transmission. The study, which is published in the April 15^th edition of the Journal of Acquired Immune Deficiency Syndromes, found that women with a CD4 cell count below 200 cells/mm³ had the highest genital shedding of HIV, but were the least sexually active. Women without any symptoms of HIV and a CD4 cell count above 350 cells/mm³ shed a smaller, but still significant amount of HIV in their genitals, and were the most sexually active.

It has been suggested that the widespread provision of antiretroviral therapy could decrease the number of new HIV infections by lowering the viral load and infectiousness of people with HIV. Current World Health Organization (WHO) guidelines recommend that antiretroviral therapy should be provided to individuals who are ill because of HIV or if they have a CD4 cell count below 200 cells/mm³. However, the impact of antiretroviral therapy on HIV risk at a population level could be limited if infectivity or high-risk sexual behaviour is high in individuals who do not qualify for treatment.

Investigators from the United States and Kenya therefore looked at the genital shedding of HIV and sexual risk behaviour of 650 HIV-positive women who had never taken antiretroviral therapy in Mombasa. They were stratified according to WHO criteria for initiating anti-HIV therapy.

The women had a median age of 29, 50% were married and 6% reported selling sex. A total of 65% of women had symptomatic HIV infection.

Genital shedding of HIV increased in a stepwise fashion with each advancement in the severity of HIV disease. Women with a CD4 cell count above 200 cells/mm³ had the highest concentration of HIV in their genitals (3.8 log₁₀ copies/swab) and women with a CD4 cell count above 350 copies/ml and no symptoms of HIV the lowest (2.4 log₁₀ copies/swab). This difference was highly statistically significant (p < 0.001). Nevertheless, the concentrations of HIV observed in the genital swabs obtained from women with the least advanced HIV disease were still high and implied a significant risk of onward transmission of the virus.

In addition, women with less advanced HIV disease reported higher levels of sexual activity. Of the 104 women with a CD4 cell count above 350 cells/mm³ and no symptoms of HIV, 60 (58%) reported sexual intercourse in the last week. This compared to 35% of women with a CD4 cell count between 200 – 350 cells/mm³ and 26% of women with a CD4 cell count below 200 cells/mm³. Condom use was low in all groups of women, ranging from a low of 6% for women with the highest CD4 cell counts and no symptoms to a high of 13% for women with a CD4 cell count below 200 cells/mm³.

“Although the most important factor in deciding when to initiate antiretroviral therapy is the potential risk vs. benefit to the additional benefit for the individual patient, additional consideration of the public health implications of treatment guidelines is important because it may help maximize the benefit for communities where antiretrovirals are being introduced,” write the investigators. Although their study found that women with the most advanced HIV disease shed the most HIV in their genitals, they stress that significant levels of shedding and high-risk sexual activity was observed in patients in the best health. Earlier initiation of anti-HIV strategy together with risk reduction counselling and the promotion of condoms may help reduce HIV transmission in this population, the investigators conclude.