Studies Examine Reducing Risk of Vertical HIV Transmission While Breastfeeding, Effect of Herpes Treatments on Transmission
HIV-positive women who are breastfeeding can reduce the risk of vertical HIV transmission if they take the antiretroviral drug nevirapine for up to six months after giving birth, according to five CDC- and NIH-funded studies conducted in Africa and India and presented Monday at the 15th Conference on Retroviruses and Opportunistic Infections in Boston, the New York Times reports.
In one of the five studies, HIV-positive women in Kenya took a combination of antiretrovirals beginning in their 34th week of pregnancy until they had been breastfeeding for six months. Their infants received the standard single dose of nevirapine after birth to prevent vertical transmission. Of the 497 infants in the Kenyan study, 12, or 2.4%, were HIV-positive one week after birth. Fifteen infants, or 3%, contracted the virus from breastfeeding eight days to 12 months after birth, the study found.
In a similar study conducted in Malawi, more than 3,000 infants received one of three treatment regimens during the first 14 weeks following birth. The study found that after nine months, HIV incidence was lowest at 3.1% among infants who received nevirapine for 14 weeks, compared with 10% in the control group, which received the standard single dose of nevirapine at birth followed by one week of treatment with another antiretroviral (Altman, New York Times, 2/5).
The other studies were conducted by Brooks Jackson of Johns Hopkins University and colleagues in Ethiopia, India and Uganda between 2001 and 2007 (Reuters Health, 2/4). For the studies, 2,000 infants received a single dose of nevirapine at birth. The infants then were randomly divided into two groups. One group received multivitamin alone for the first six weeks. The other group received a multivitamin plus nevirapine for the first six weeks (NIAID bulletin, 2/6). After six months, the risk of HIV or death was one-third less among the infants who received a multivitamin and nevirapine than among the other infants, the study found (Reuters Health, 2/4).
According to the Times, the studies' findings "open the way" for new strategies to prevent vertical transmission in developing countries, where HIV-positive women often must breastfeed because of a lack of access to formula or clean water, strong cultural traditions of breastfeeding or fear of stigmatization for not breastfeeding. Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases, said the studies "could serve as the basis of a new standard of care," adding that the next step is to "determine the optimal time for treating mothers and infants" (New York Times, 2/5).
In related news, another study presented Monday at the conference found that treating genital herpes with the drug acyclovir does not prevent or reduce the risk of HIV transmission, the San Francisco Chronicle reports. According to the Chronicle, many researchers believed that treating herpes would reduce susceptibility to HIV because numerous studies in the past 20 years have found that herpes increases the risk of HIV by creating lesions that serve as points of entry into the body for the virus.
The study was conducted among 3,000 men who have sex with men in New York, Peru, San Francisco and Seattle, as well as women in Africa (Russell, San Francisco Chronicle, 2/4). Half of the participants took acyclovir and half took a placebo. The study found that people who took acyclovir to treat herpes contracted HIV at the same rate as those who took a placebo (Fox, Reuters Health, 2/4). The study also found that acyclovir reduced herpes lesions by different percentages in different groups: 32% among African women, 41% among MSM in Peru and 50% among MSM in the U.S.
According to the Chronicle, one possible reason the herpes treatment did not prevent HIV is that it does not eradicate herpes, meaning that people who take acyclovir continue to have occasional genital ulcers, which increase the risk of HIV. A possible solution would be to increase the number of acyclovir pills beyond two daily, the Chronicle reports. According to Connie Celum, a researcher at the University of Washington who led the study, previous studies have shown no significant improvement in herpes suppression with higher doses (San Francisco Chronicle, 2/5). In addition, Rowena Johnston, vice president of research for the American Foundation for AIDS Research, said it is possible that herpes causes immune cells to circulate actively in the body, increasing the risk of HIV (Reuters Health, 2/4).
Celum said that despite the study's "disappointing" findings, she will continue another study currently under way that aims to determine whether herpes treatments block HIV among couples in which one partner is HIV-positive. That study is expected to end in June, and results are expected in about one year, the Chronicle reports (San Francisco Chronicle, 2/5).