The World Health Organization estimates that 40 million people are infected with the AIDS virus, 95 percent of them in developing countries. In some African countries, 40 percent of pregnant women have the virus. Last year, an estimated 700,000 children caught HIV.
In impoverished areas where the risk is greatest, researchers have settled on a simple, one-time treatment for HIV-infected pregnant women to keep them from passing the virus to their newborns. The treatment, using the drug nevirapine, is easy, inexpensive and effective, typically cutting the risk of HIV transmission in half.
However, new findings suggest a potentially important trade-off for the mother that could complicate her later treatment, if it is available. Earlier studies had suggested that the single dose of the drug might make the virus impervious to later treatment, but until now there has been no clear evidence whether the theoretical risk is real.
One study, conducted in South Africa, found that 39 percent of HIV-infected women who get nevirapine during pregnancy go on to harbor virus that is resistant to the drug. Another, done in Thailand, shows the potential consequence: The mothers who eventually need drug treatment for their infection are much less likely than usual to respond to it.
In the United States and Europe, pregnant women with HIV are routinely given combinations of powerful AIDS drugs throughout their pregnancy. This reduces the risk of passing the virus on at birth to near zero and minimizes the chance of developing resistance.
In Africa and other places where this approach is not considered practical, the WHO has recommended giving a single dose of nevirapine when labor starts and then giving a second pill to the baby two days after birth.About 8 percent of babies catch the virus after nevirapine, compared with about 20 percent of those who get no treatment.
From their study researchers found that women who had gotten nevirapine during pregnancy were much less likely to do well on a standard three-drug regimen if they developed AIDS. Three-quarters responded to treatment if they had never received nevirapine during pregnancy, compared with just one-third of those who had developed resistant virus because of their pregnancy treatment.
Thus researchers conclude that more research and studies need to be done till a solution is found.