EPIDEMIOLOGY For the first time, a study of HIV-infected pregnant women has found that coinfection with malaria significantly increased a mother's risk of transmitting the AIDS virus to her baby before or during birth. According to a report in the November issue of the journal AIDS , HIV-infected pregnant women in the Rakai district of Uganda had nearly three times the risk of transmitting the AIDS virus to their babies if they concurrently had malaria and if the parasite that causes the disease had infected their placentas. “I was startled by the findings,” says the paper's first author, epidemiologist Heena Brahmbhatt of Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. In January 2002, Brahmbhatt, then a Ph.D. candidate at Hopkins studying mother-to-child transmission (MTCT) of HIV, read a report that an antimalarial drug might reduce HIV transmission to infants through their infected mother's breast milk. Intrigued by the possible impact of the drug, Brahmbhatt asked her adviser, Hopkins epidemiologist Ronald Gray, if she could look for the effect of malaria in data from Gray's well-known Rakai study. The study, conducted in collaboration with several Ugandan research groups, evaluated MTCT in 746 HIV-infected pregnant women and their babies in Uganda's Rakai district from 1994 to 1999. Brahmbhatt found 93 cases in which the researchers had ascertained the baby's HIV status and also had preserved the placenta. Of the 15 babies whose mothers had placental malaria, she found that six (40%) became infected. In contrast, HIV spread to only 12 of 78 infants (15%) whose mothers did not have malaria in their placentas. Brahmbhatt emphasizes that the sample size is small, and the findings are not conclusive. Still, the results were statistically significant, leading the authors to conclude that trials are “urgently needed” to evaluate whether giving HIV-infected pregnant women malaria prophylaxis can also reduce the transmission of HIV. “If our observations pan out, there may be a case for much more aggressive malaria suppression in HIV-infected women during pregnancy,” says Gray. ![Figure][1] Net gain. Protecting pregnant women from malaria may help thwart the spread of HIV from mother to child. CREDIT: ORC MACRO/CSTS+PROJECT Few studies have been done on the relationship of placental malaria and the maternal transmission of HIV. In 1998 a preliminary report on HIV-infected women in Kisumu, Kenya, hinted at a similar effect. But a lead investigator in that work, Richard Steketee of the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, says a more thorough analysis showed that, overall, placental malaria did not increase a woman's risk of transmitting HIV to her baby. “The [Rakai and Kisumu] studies don't match up, but that doesn't mean either one is wrong, because the methodology is different,” says Steketee, who heads CDC's malaria epidemiology branch. Steketee's results, in press at Emerging Infectious Diseases , offer a clue to the complex interaction of the two diseases in a pregnant woman. In Kisumu, the researchers assessed the parasitic burden in the placentas. Curiously, they found some protection from HIV when a placenta had a low level of parasites, but the risk of MTCT increased when the parasite density rose to high levels. Hopkins's Gray says he and his co-workers now plan to conduct a similar analysis in the placentas they collected. Steketee suspects that the intensity of the malaria infection modifies the mother's immunity in different ways, affecting HIV's ability to transmit in utero. “It would be important for someone to look at this again,” says Steketee. “These are not easy studies and they are not cheap, but the impact could be substantial.” [1]: pending:yes