Scientists said they had unravelled the genetic codes of parasites responsible for the bulk of malaria cases outside Africa, and found they were scarily diversified and may be harder to kill.
In a study published in Nature Genetics, researchers said they had sequenced the genomes of four strains of Plasmodium vivax - a parasite that infects about 100 million people every year.
Other research had found that 10%-20% of P. vivax cases occur in Africa south of the Sahara - a region mainly affected by the P. falciparum parasite which causes the most malaria deaths worldwide.
Outside of Africa, P. vivax accounts for half of all malaria cases, mainly in the Middle East, the Western Pacific and Central and South America.
Both parasite species are transferred by Anopheles mosquitos. P. vivax is more resilient than its deadlier, tropical cousin, and can stay in remission for longer and tolerate cooler climates. Yet much less is known about P. vivax, and less attention has been paid to unravelling its genetic code than that of P. falciparum.
With their research, a team from India and the United States say they have tripled the number of genome sequences available for P. vivax.
They said they observed an "extremely high genomic diversity", suggesting it may be even harder than for P. falciparum to develop a single vaccine targeting several different strains of P. vivax.
In 2010, malaria infected about 216 million people and claimed an estimated 655 000 lives - mainly in Africa where a child dies of the disease every minute, says the World Health Organisation.
Symptoms include fever, headache, chills and vomiting which if not treated within 24 hours can progress to severe illness and even death.
In a second Nature Genetics report, scientists in Japan and the United States said they had sequenced the genomes of three strains of P. cynomolgi - a sister species to P. vivax and a cause of malaria in Asian Old World monkeys.
Since it is so closely related, information on the DNA code of P. cynomolgi "provides the foundation for further insights into traits that will enhance prospects for the eventual elimination of vivax-caused malaria and global malaria eradication," they wrote.
(Sapa, August 2012)
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