American Foundation for AIDS Research, October 2004
Kristen Kresge

August 2004 — Highly burdened regions for malaria and HIV overlap geographically, yet researchers know little about treating both diseases simultaneously. In Africa, the impact of this coinfection on children and pregnant women — the two high-risk groups for malaria — is of particular concern. Several studies evaluating HIV transmission from coinfected mothers to their babies have produced conflicting results. But a recent study concluded that babies of coinfected mothers are much more likely to contract HIV, regardless of maternal viral loads.

“The two epidemics have a synergistic affect on each other. They both facilitate progression of the other disease,” said Dr. Heena Brahmbhatt of Johns Hopkins University. She reported on a study involving 300 Ugandan women in a late-breaker session at the XV International AIDS Conference in Bangkok (Int Conf AIDS. 2004 Jul 11-16;15:Abstract No. LbOrC20).

Because of the synergism between HIV and malaria, women battling coinfection often have higher levels of virus in their blood than women with only HIV. A higher viral load at delivery is the greatest risk factor for mother-to-child transmission of HIV. But Brahmbhatt found that despite disease status, coinfected mothers had HIV-infected babies more often, suggesting another factor exists. The rates of transmission were 31% in coinfected women, versus only 8% in mothers with HIV alone.

A possible explanation is the concentration of parasite within the placenta, which may damage the placental barrier and put the baby in contact with more of the mother’s blood. This is one of several hypotheses, according to Brahmbhatt.

She and her coauthors recommend that pregnant women in malaria-endemic areas take malaria prophylaxis and antiretrovirals to further reduce their chances of transmitting HIV. “We really need to target women at antenatal clinics for both HIV and malaria,” said Brahmbhatt. She also calls for more research on the effects of combining these treatments.

Few studies on the interactions between malaria and HIV drugs exist. One examined the combination of ritonavir and the antimalarial mefloquine. Another study by Andrea Savarino (J Acquir Immune Defic Syndr. 2004 Mar 1;35(3):223-32) focused on protease inhibitors and chloroquine. The latter study used animal models but suggested that chloroquine can raise or lower protease inhibitor levels, depending on the antimalarial concentration.

Studies on how antiretrovirals affect the potency of malaria drugs are even more urgent. Fluctuations in protease inhibitor concentrations over a short time should have minimal impact on viral control. Weakening the potency of antimalarials, however, could jeopardize their ability to rid the parasite from the body.

Research is required to answer the complex questions of treating coinfected people. “This costs money and effort,” explained Allan Schapira, coordinator of malaria policy at the WHO. “We need scientists to get proactive and submit proposals.”

HIV-positive people traveling to endemic areas need to learn about how to treat and prevent malaria. Only three preventative malaria drugs are currently recommended for people in North America traveling abroad: doxycycline, mefloquine, and atovaquone/proguanil. Still, HIV/malaria coinfection remains a minor concern in Western countries, and drug companies are unlikely to fund interaction studies.

In endemic countries, the issue of coinfection is relegated to the shadows in the face of more dire concerns, such as accessing any treatment at all. “Antiretroviral treatment is only now beginning to become widespread in Africa, and so many issues have to be addressed with both HIV and malaria,” said Schapira. “You have to do things piece by piece.”

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