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Malaria drugs may boost viral activity.

Malaria Drugs may boost viral virility

Mouse studies suggest that five of the most commonly used antimalaria drugs may make individuals especially susceptible to viral diseases, including AIDS. If confirmed in humans, this could portend a no-win predictment for the millions of Africans who live virtually surrounded by both the AIDS virus and the deadly malaria-causing protozoan Plasmodium falciparum.

Radha K. Maheshwari and his coleagues at the Uniformed Services University of Health Sciences in Bethesda, Md., gave healthy mice one of five different antimalaria drugs and then injected the animals with either of two tropical viruses -- Semliki Forest virus or encephalomyocarditis virus. At blood concentrations equivalent to therapeutic levels in humans, the antimalaria drugs significantly enhanced viral replication, leading to more rapid onset of disease and higher death rates in the treated mice compared with untreated mice challenged with the same viruses.

The researchers say their data are consistent with in vitro experiments by others suggesting that antimalaria drugs may enhance the activity of the AIDS virus and Epstein-Barr virus, which has been associated with a cancer called Burkitt's lymphoma. They say their experiments -- the first to test the phenomenon in vivo--"suggest that the widespread use of antimalarials in malaria-endemic areas may predispose the population to significant viral infections, including AIDS." The team presented its data in New Orleans last week at the annual meeting of the American Society of Tropical Medicine and Hygiene.

Scientist know that chloroquine, the most commonly prescribed antimalaria drug, suppresses the immune system, says William K. Milhous of the Walter Reed Army Institute of Research in Washington, D.C. However, he adds, it's not obvious why other, chemically unrelated antimalarials would also do so.

In the mouse experiments, all five drugs suppressed the disease-fighting "natural killer calls" and apparently blocked the action of interferon, an immune-enhancing chemical secreted by several types of white blood cells. Nothing that physicians in Africa often prescribe synthetic interferon to help ward off infections, the researchers warn that antimalaria drugs might render that treatment useless.

Milhous says scientists will have to perform similar studies in primates to help determine whether the new findings apply to humans.
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Author:Weiss, Rick
Publication:Science News
Date:Nov 17, 1990
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