Associated Press: Genes sequenced for malaria parasite, mosquitoes that spread it

by Paul Recer

WASHINGTON — Researchers have mapped the genes of the parasite that causes malaria and the mosquito that spreads it, breakthroughs that may lead to better insecticides and repellents against the insect and new ways to combat the disease. The ancient scourge kills almost 3 million people a year.p. The double triumph pumps hope into a worldwide effort against malaria in an age when the disease is gaining strength in Africa. Up to 1,800 African children under 5 die each day of its shivering chills and brutal fever.

In parallel efforts that involved more than 160 researchers in 10 countries, scientists mapped the genes for Plasmodium falciparum, the deadliest form of malaria, and for Anopheles gambiae, a mosquito that prefers human prey and spreads malaria to millions with its bloodsucking bite.

The British journal Nature published the complete genetic sequence of P. falciparum. The mosquito genome is being published by the American journal Science. The achievement was announced today in London and in Washington.

“This is an extraordinary moment in the history of science,” said Carlos Morel of the World Health Organization. “At last, the enormous power of modern technology is penetrating the mysteries of an ancient disease … which continues to kill millions.”

Neil Hall of the Wellcome Trust Sanger Institute in the United Kingdom, one of the participating labs, said the gene map provides new molecular targets for vaccines and drugs.

“We have presented scientists with the haystack,” Hall said. “They have got to go out and find the needle.”

New drugs are desperately needed, said Stephen Hoffman, a co-author of the study who was a researcher at the Naval Medical Research Center in Silver Spring, Md.

Hoffman said all of the major drugs now in use are very old and their effectiveness is fading rapidly.

“The drugs that we use to treat malaria were introduced 50 to 2,000 years ago,” said Hoffman.

He said German researchers already are developing a drug they first tested after spotting a genetic vulnerability in one chromosome of the parasite.

Frank H. Collins, a mosquito expert at Notre Dame University, said studies of the Anopheles gambiae genome have revealed genes that may explain why the mosquitoes favor humans above all other prey.

He said genes linked to the insect’s sense of smell may be exploited to develop new repellents, while other genes may lead to novel insecticides.

Completing the gene mapping of malaria and the mosquito comes at a critical time in international public health, officials said. Studies show malaria is becoming increasingly resistant to chloroquine, a drug that has held the line against the disease for decades. At the same time, the mosquito has become tougher to control with current insecticides.

The advances also come in an era when some experts fear a warming climate will let the resistant malaria parasite move into areas where it has been rare or unknown. Malaria, though of a different strain, was detected in both humans and mosquitoes in Virginia recently, the first time in two decades that a wild reservoir of malaria has been found in this country. Hoffman said 300 million to 900 million people are infected with malaria each year, including 10,000 to 30,000 travelers who visit malaria-infested areas and return home with the disease.

The mosquito is a key part of the three-stage life cycle of the malaria parasite.

The female A. gambiae requires a blood meal to mature its eggs. An insect infected with malaria injects the parasite into a human when it sucks up blood. The parasite invades first the liver and then red blood cells. When another mosquito bites, parasites transfer into the new insect, which then bites another human and the cycle begins anew. Malaria causes chills and fever, with temperatures rising to 105 or higher, often with headaches, muscle pain and vomiting. Repeated attacks can cause death.

OCT. 3, 2002

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