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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