/ 26 October 2005

New Aids drug could help prevent malaria

A drug designed to protect people with HIV/Aids from dangerous bacterial infections could also protect them against malaria, according to a report on the Science and Development Network website.

Combining treatments in this way could be a major advantage in Africa, where many people have little or no access to malaria drugs. The African team of researchers says that although the drug should not be used solely against malaria, it could save the lives of thousands of HIV-infected Africans — especially pregnant women — for whom malaria presents a huge health risk.

The researchers, led by Mahamadou Thera at the University of Bamako, Mali, published their findings online in the Journal of Infectious Diseases.

The team looked at how well the cheap and widely available drug trimethoprim-sulfamethoxazole could prevent malaria in 245 children in Mali who did not have HIV/Aids. Two-thirds of the children were given the drug for 12 weeks; the other third nothing.

The team showed that of the 157 children given trimethoprim-sulfamethoxazole, only one developed malaria. But of the 77 children not taking the drug, 72 got malaria. The children given trimethoprim-sulfamethoxazole also had fewer gastrointestinal illnesses than the other group.

One of the researchers, Christopher Plowe at the United States-based University of Maryland School of Medicine, told SciDev.Net that the team does not advocate using trimethoprim-sulfamethoxazole solely to prevent or treat malaria in Africa, partly because of fears of creating more drug resistance.

However, he says, the team’s evidence suggests that worries about drug resistance should not prevent the widespread use of trimethoprim-sulfamethoxazole in those with HIV.

The World Health Organisation is expected to release new guidelines for using the drug in Africa soon.

Meanwhile, Australian laboratory scientists say they’ve found other drugs that can tackle both HIV and malaria. Researchers from the Queensland Institute of Medical Research assessed the effect of six commonly used HIV drugs on the malaria parasite — Plasmodium falciparum — in laboratory tests.

Three of the drugs stopped the parasite from growing, while three had no effect. The drugs block an important parasite molecule and were effective against malaria parasites that are resistant to currently used drugs, according to a study in the Journal of Infectious Diseases.

The drugs currently “do not form part of the first-line treatment of HIV in developing countries”, says Stephen Rogerson, a malaria researcher at the University of Melbourne. “For two reasons: expense, and in many instances the need for cool storage of the drugs.”

However, Rogerson told SciDev.Net that “growing evidence shows that HIV-infected people respond less well to standard malaria therapy”, suggesting the need for a new class of anti-malarial drugs specifically for those with HIV.

Although the Queensland researchers do not believe that these drugs would be the first choice to treat malaria patients initially, they think they have identified a chink in the parasite’s armour that could be explored for the development of new drugs.

The researchers say they are not sure exactly how the drugs act against the malaria parasite. One theory they propose is that the drugs inhibit an enzyme the parasite uses to digest haemoglobin, the pigment in human blood that allows transport of oxygen.

The next step, they say, is to test these results in patients who have both HIV and malaria to determine how the drugs work in combination with others. — SciDev.Net