'Benign' malaria found to just as deadly

Australian scientists have found that a strain of malaria previously considered to be 'benign' is actually potentially fatal.

The scientists from the Menzies School of Health Research, in Darwin challenge the current perception that Plasmodium falciparum (P. falciparum) can be severe and life-threatening whereas Plasmodium vivax (P. vivax) tends to be mild.

P. vivax and P. falciparum are the two major strains of malaria which affect humans and traditionally, attention has focused on P. falciparum, which is the dominant strain in Africa and considered to be the more virulent and deadly strain of the disease.

Almost half of the malaria prevalent in Asia is due to P. vivax and there are as many as 400 million cases of vivax malaria each year - 300 cases are reported each year in people returning to Australia from malaria endemic countries.

The parasite has developed resistant to standard treatments making it difficult to treat in countries such as Indonesia and Papua New Guinea (PNG) and new research conducted in PNG and Indonesia has shown that P. vivax is far from benign.

Dr. Ric Price and his colleagues examined data collected from all the patients attending outpatient and inpatient departments of a hospital that serves a large area in the southern lowlands of Papua between January 2004 and December 2007.

P. vivax was found to be responsible for a significant amount of illness with high rates of severe disease and death and in many cases, victims were infected with a mixture of both parasites with a resulting higher still risk of severe disease than infection with a single parasite.

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Dr. Price says that the findings provide important information about the burden of malaria associated with P. vivax infection and should focus attention on treating and preventing the disease.

Dr. Price says the research revealed that in a region where multidrug-resistant strains of malaria are common, P. vivax infection is associated with severe and fatal malaria, particularly in young children.

Dr. Price also says it shows that people infected with both types of malaria parasites are more likely to suffer from a severe case of malaria and die from the disease.

He says both strains of malaria must be considered when measures are implemented to eliminate these parasites from regions where they co-exist.

Dr. Price says more research is needed in other settings to confirm the findings and to learn more about the pattern of severe malaria associated with P. vivax, in particular, with multi drug-resistant strains.

Experts say calls for increased efforts to control malaria internationally will need to ensure that P. vivax receives appropriate attention.

The study is published this week in the International journal PLoS Medicine.