Do all mosquitoes transmit malaria?

Online Q&A
Updated January 2014

Q: Do all mosquitoes transmit malaria?

A: Only certain species of mosquitoes of the Anopheles genus—and only females of those species—can transmit malaria.

Malaria is caused by a one-celled parasite called a Plasmodium. Female Anopheles mosquitoes pick up the parasite from infected people when they bite to obtain blood needed to nurture their eggs. Inside the mosquito the parasites develop and reproduce. When the mosquito bites again, the parasites mix with its saliva and pass into the blood of the person being bitten.

Malaria parasites multiply rapidly in the liver and then in red blood cells of the infected person. One to two weeks after a person is infected the first symptoms of malaria appear: usually fever, headache, chills and vomiting. If not treated promptly with effective medicines, malaria can kill by infecting and destroying red blood cells and by clogging the capillaries that carry blood to the brain or other vital organs.

There are four types of human malaria: Plasmodium vivax, P. malariae, P. ovale and P. falciparum. P. vivax and P. falciparum are the most common forms. Falciparum malaria—the most deadly type—is most common in sub-Saharan Africa, where it causes nearly a million deaths a year.

In recent years, some human cases of malaria have also occurred with Plasmodium knowlesi – a species that causes malaria among monkeys and occurs in certain forested areas of South-East Asia.

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