Researchers map malaria parasite P vivax; Nearly 3B people at risk of infection in 2009

A new evidence-based map estimates that in 2009 2.85 billion people lived "at risk of infection" with the malaria parasite Plasmodium vivax, BMJ News reports. As described in a study, published Tuesday in PLoS Neglected Tropical Diseases, P vivax "is more widespread and potentially represents a greater burden on human health in some parts of the world than P falciparum, the species usually associated with the greatest mortality and morbidity," BMJ News writes (Moszynski, 8/3).

The majority of the global population (91 percent) at risk of P vivax lives in central and southeast Asia, Reuters reports. "P vivax remains the most widely distributed human malaria parasite even after a century of development and control," Simon Hay, a co-author of the study, told the news service. Mapping the parasite is important "so that plans can be made to control it, wrote Carlos Guerra, another author" (8/3).

"Risk areas were refined using temperature and aridity data based upon their relationship with parasite and vector bionomics," Press Trust of India reports (8/4).

The study was conducted as part of the Malaria Atlas Project, "a multinational research collaboration funded mainly by the Wellcome Trust," BMJ News continues. The researchers used "novel methods," including "developing new global maps of Duffy negativity, which confers partial protection against P vivax. People who are Duffy negative lack an antigen on the surface of red blood cells that codes for a protein receptor for P vivax."

BMJ News continues: "Globally P falciparum 'is undeniably the main killer' of the two, Dr. Guerra said. Even though worldwide more people are exposed to risk of P vivax infection than P falciparum, most deaths from malaria are reported in Africa, 'where P vivax infection is rather uncommon due to the high prevalence of Duffy negativity in large parts of the continent,' he added" (8/3).

Reuters also reports on another article published Tuesday in PLoS Medicine that concludes, "vector control measures such as insecticide-treated nets and sprays have not been able to break the transmission cycle of the Plasmodium falciparum, another parasite that causes malaria in the most endemic parts of Africa and the Pacific." Researchers said that "priority areas" will include better understanding the aspects mosquito life cycle that "directly mediate malaria transmission," according to Reuters (8/4).