Plasmodium vivax, a strain of malaria thought to be mild and non-life-threatening is potentially fatal, according to a new study. Two malaria strains, P. vivax and P. falciparum, affect humans. The latter, the dominant strain in Africa, is considered to be more virulent and deadlier. But P. vivax accounts for 400 million cases every year in Asia, with about 300 cases reported annually in patients returning to Australia from malaria endemic countries. In Indonesia, the parasite has developed resistance to standard treatments. The new research has shown that P. vivax is responsible for a significant illness with high rates of severe disease. The paper shows that victims infected with both parasites and that this results in an even higher risk of severe disease than infection with a single parasite. The study's author Mr Ric Price of Charles Darwin University, said that these findings provide important information about the burden of malaria associated with P. vivax infection. "Our findings show that in a region where strains of malaria are common, P. vivax infection is associated with severe and fatal malaria, particularly in young children," he said.