Scientists Offer New Explanation for Intercontinental Spread of Drug-Resistant Malaria

SAN ANTONIO -- Africa's increasing incidence of  drug-resistant malaria resulted from mutant parasites transported from Asia,  according to an article in the Aug. 20, 2004 issue of the journal Science.

Researchers say people's global mobility makes the further spread of

mutant parasites likely, and they recommend a united international effort to

prevent this from happening with malaria and other diseases.

Contrary to the common presumption that new genetic mutations in the

malaria parasite occur repeatedly in malaria-affected regions, scientists now

show that these genetic mutations are rare; when they have occurred, the drug-

resistant parasites have been exported from one region or continent to

another, resulting in a rapid spread of resistance to low-cost drug treatments

and a rise in malaria's death toll.

The Science article, "Intercontinental Spread of Pyrimethamine-Resistant

Malaria" explains findings that a triple-mutant, highly drug-resistant malaria

parasite that originated at a single point in Southeast Asia is the same

strain spreading through Africa.  Co-authors include Tim Anderson and Shalini

Nair at the Southwest Foundation for Biomedical Research, lead author Cally

Roper at the London School of Hygiene and Tropical Medicine, and other

collaborators from Africa and Thailand.

In 2003, Nair and Anderson published results from DNA-fingerprinting tests

revealing that all the drug resistance of mutant malaria parasites in five

countries of Southeast Asia could be traced to a single origin.

Roper led a similar study in a southeastern region of Africa and published

comparable findings, that mutant parasites in a 4,000-square-kilometer-region

of Africa also had a single origin.

After the 2003 publications, the Anderson and Roper laboratories compared

findings and discovered that the mutant parasites in Africa had the same

fingerprint as those in Asia, indicating that they did not appear there on

their own, but instead jumped continents. 

Now Anderson asks, "What is going to happen when the parasite with four

mutations jumps from Asia to Africa, as we can be sure it will given the

mobility of people in today's world?"  That is why he and his colleagues are

calling for a unified international response.

Source:  Southwest Foundation for Biomedical Research