(Plasmodium falciparum, Plasmodium malariae, Plasmodium vivax, and Plasmodium ovale)
Malaria is a serious disease caused by a microscopic parasite that affects red blood cells. There are four species of malaria parasite: Plasmodium falciparum, P. malariae, P. vivax, and P. ovale. The severity of disease depends on the species of Plasmodium causing the infection. The parasite is transmitted by the bite of an infected Anopheles mosquito, commonly found in tropical and subtropical regions of the world. Malaria can also be transmitted from mother to fetus, via blood transfusions, organ transplant, or use of shared needles and syringes contaminated with infected blood.
People usually become ill with malaria within 7 days to 30 days after being bitten by an infected mosquito. Infection with malaria parasites may range from absent of symptoms to severe illness, including death. Initially, symptoms include fever, chills, sweats, headaches, nausea and vomiting, body aches, and general malaise. Severe symptoms may include neurologic abnormalities, severe anemia, acute respiratory distress syndrome, decrease in blood platelets, low blood glucose, cardiovascular collapse and shock, and acute kidney failure.
Most of the malaria cases in the United States are reported from returning travelers and immigrants. In Wisconsin, an average of 12 cases of malaria was reported annually between 2002 and 2009. All illnesses were reported from people who traveled to a malaria endemic country.