February 12, 2003
Dr. Baeten, from University of Washington in Seattle, presented
information on behalf of his research group in Mombasa, Kenya. They have
been interested in ways to prevent HIV infection in women and to slow
progression once infected. Vitamin A deficiencies are common in Kenya and
have been associated with higher HIV viral loads and advanced disease.
Consequently, they studied whether giving vitamin A supplements would
decrease HIV viral load and disease progression.
They randomized 400 HIV-infected women to vitamin A or placebo. Unfortunately, they found that vitamin A supplements did not lower HIV viral loads or slow disease progression even when just looking at women with vitamin A deficiency. Dr. Baeten suggested that vitamin A deficiency might be a result of high HIV viral load and advanced disease rather than a cause. In a parallel study, they randomized women to multivitamins or placebo and found that multivitamins actually increased vaginal shedding of HIV and did not affect the HIV viral load or CD4 in the blood.
Then Dr. Baeten discussed their study of 1,500 female sex workers from Kenya and their risk of HIV infection as it relates to use of hormonal contraception. The two types of hormonal contraception were oral contraceptives (OCT) and depot medroxyprogesterone acetate (DMPA), an injection given every three months to prevent pregnancy. They found that women using hormonal contraception were twice as likely to become infected with HIV than women not on hormonal contraception. Possible explanations include a thinning of the surface of the vagina and changes of the cervix associated with hormonal contraception.
In addition, they found that women using DMPA at the time of acquiring HIV had a higher viral load and increased viral diversity (meaning that the virus changed and mutated more often). It is difficult to say what this means for women's reproductive health. Because women in developing countries such as Kenya are much more at risk for dying during childbirth than women in the U.S. or Europe, it is unclear whether this increase in HIV infection is more important than the risk of unwanted pregnancies. Given that over 100 million women worldwide use hormonal contraception, this issue is of critical importance and is fortunately a focus of other large ongoing trials.