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Treating Fever Has Double Malaria Benefit - 2002-08-14

Treating the high fever that accompanies malaria not only makes an infected person feel better, it also hastens recovery. researchers say keeping the body cool makes antimalarial drugs more efficient at killing the parasite that causes the disease.

Falciparum malaria is responsible for between one and three million deaths around the world each year. The parasite, which is transmitted by the bite of an infected mosquito, kills by multiplying rapidly inside stricken individuals.

Tropical medicine Professor Nicholas White of Oxford University and Mahidol University in Thailand says the parasite has a unique mechanism for evading antimalarial drugs. It makes a glue out of proteins inside red blood cells and adheres to the surface of the cells.

"We've been studying,- like many people have been studying, this phenomenon for a long time because we think it's the essential pathological feature of severe malaria," said Professor White. "In fact, all these parasitized red blood cells get stuck in the vital organs and cause a traffic jam and the circulation through these organs is impaired, a bit like the traffic jam in Bangkok in the morning, nothing gets past."

In a study of blood smears taken from people infected with malaria, Professor White and colleagues found malaria parasites did not stick to red blood cells at 37 degrees Celsius, the normal body temperature. However, at slightly elevated temperatures, perhaps 38 or 39 degrees, the parasites stuck.

Dr. White says the finding explained something that was discovered several years ago in Africa that was considered bad news at the time.

That was, if you gave people with malaria drugs to stop fever, the parasites stayed in the blood a little longer and could not be killed by antimalarials that target the parasites when they are stuck to red blood cells.

"Instead of it being a bad thing, it was a good thing because they are now still circulating, not blocking up the blood vessels," said Professor White. "And you can catch them them with the drugs. You could kill them before that bad stage, that pathological stage."

Thanks to the discovery of new antimalarial drugs that kill the parasite when it is young and still floating around in the bloodstream. The drugs are derivatives of the Chinese herb "artemisinin."

Unfortunately, the malaria parasite has become resistant to many of the older antimalaria drugs, incuding chloroquine, which targets the parasite at an older stage in its life cycle But Dr. White says the combination of artemisinin and chloroquine works very well in fighting the disease.

Professor White helped conduct clinical trials that demonstrated the effectiveness of artemisinin in killing the malaria parasite in its youthful stage.

U.S. regulators recently recommended the approval of the herb for the treatment of malaria.