Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by parasitic protozoans of the genus
Plasmodium. Commonly, the disease is transmitted by a bite from an infected female
Anopheles mosquito, which introduces the organisms from its saliva into a person's circulatory system. In the blood, the parasites travel to the liver to mature and reproduce. Malaria causes symptoms that typically include fever and headache, which in severe cases can progress to coma or death. Five species of
Plasmodium can infect and be transmitted by humans. The vast majority of deaths are caused by
P. falciparum and
P. vivax, while
P. ovale, and
P. malariae cause a generally milder form of malaria that is rarely fatal. The zoonotic species
P. knowlesi, prevalent in Southeast Asia, causes malaria in macaques but can also cause severe infections in humans. Malaria is common in tropical and subtropical regions because rainfall, warm temperatures, and stagnant waters provide an environment ideal for mosquito larvae.