A resurgence of malaria in parts of Africa is raising questions about whether current control mechanisms are failing. It could be, some researchers say, that mosquitoes are becoming resistant to the insecticide used on bed nets. Or that people are losing their partial immunity to malaria, gained from repeated exposure to the parasite that causes it.

HSPH malaria expert Dyann Wirth, commenting on NPR’s health blog, “Shots,” noted that malaria “immunity” cannot prevent reinfection from the disease, only reduce its severity.

“We don’t really know what we mean when we talk about immunity to malaria, the way you can with measles,” said Wirth, chair of HSPH’s Department of Immunology and Infectious Diseases and Richard Pearson Strong Professor of Infectious Diseases. “So it’s hard to measure.”

She added that it’s also possible that when malaria rates dropped several years ago, people stopped seeking care as frequently, thus creating “a reservoir of infected people” on whom mosquitoes can feed, thus starting another cycle of transmission.

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