|HIV infection impairs immunity to malaria in pregnant women|
|June 04, 2004|
CHAPEL HILL -- Scientists studying infections with HIV -- the virus that causes AIDS -- and malaria have found a strong link between the two illnesses, both major scourges in sub-Saharan Africa.
One of their reports, appearing in the April 30 issue of the journal AIDS, shows that malaria makes HIV worse in pregnant women and may increase the risk of transmission of HIV to their babies.
A new paper will be published in the June 5 issue of the Lancet, a British medical journal. It reports for the first time that HIV impairs immunity to malaria in pregnant women.
Together, the work demonstrates that interactions between malaria and HIV make women with both infections much worse off than those with either one alone, the scientists say.
Authors include Drs. Stephen Rogerson and Adele M. Mount of the University of Melbourne in Australia, Dr. Steven Meshnick of the University of North Carolina at Chapel Hill and Dr. Victor Mwapasa of the University of Malawi, one of Meshnick's former students. Rogerson was the principal investigator for the Lancet study.
"This work is important because it suggests that if we can protect women from malaria when they are pregnant, we might be able to reduce the likelihood of their transmitting HIV to their babies," Meshnick said. "Also, if a woman has both diseases, it shows you need to control the HIV to make her less susceptible to malaria.
"In other words, the two infections go hand-in-hand," he said. "The findings also suggest that two important programs in Africa -- to prevent malaria in pregnancy and mother-to-child transmission of HIV -- ought to be combined."
The studies involved testing women in labor for both HIV and malaria, said Meshnick, professor of epidemiology and microbiology at the UNC schools of public health and medicine. If they tested positive for HIV, doctors gave them nevirapine to prevent or reduce transmission of the virus to the babies. Malaria infections were treated with sulfadoxine-pyrimethamine or quinine, which are standard treatments in Malawi.
Clinicians also followed the infants -- testing them at birth, at six weeks and 12 weeks to learn if they had HIV in their bloodstreams.
Blood analyses revealed that simultaneous malarial infections almost doubled the number of HIV particles in patients' blood when compared with women not suffering from malaria, Rogerson said. The difference was even more striking when they measured HIV viral loads in the placenta.
"In the second paper, we described finding that HIV-infected pregnant women mounted a much weaker antibody response to the malaria parasite than HIV-uninfected women," he said. "Normally, this antibody response helps eliminate malaria parasites. This could explain why HIV-infected pregnant women suffer worse malaria, an observation made earlier in several parts of Africa."
Tens of millions of African women are exposed to malaria during pregnancy each year, Meshnick said. Often, their babies have low birth weights and face a strongly reduced chance of surviving their first year of life. Malaria is the most frequent preventable cause of complications in pregnancy in Africa.
"In Malawi, about a third of new mothers suffer from malaria, and about a third are HIV-infected," he said. "Roughly 10 percent have both illnesses."
The findings highlight an important mechanism by which HIV infection increases susceptibility to malaria in pregnant women, the authors said. It likely will have important implications for malaria vaccine development in this group and may also be relevant to malaria susceptibility in other HIV-infected groups.
The National Institutes of Health and the Wellcome Trust supported the research.
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This article was researched and written by David Williamson of UNC News Services.