Malaria is a potentially deadly disease of the blood caused by a parasite, which is most often transmitted to humans by the bite of an infected mosquito. Although uncommon in temperate climates, it is still prevalent in tropical and subtropical countries.

Symptoms usually begin a few weeks after infection, although they can lay dormant in the body for up to a year. They include fever, sweating, headache, diarrhea, and vomiting. If drugs are not available or if the parasites are resistant to them, malaria infection can develop to anemia, breathing problems, hypoglycemia or cerebral malaria. Cerebral malaria can cause coma, life-long learning disabilities, and death.

The risk of disease can be reduced by preventing mosquito bites through the use of mosquito nets and mosquito repellents, or by spraying insecticides and draining standing water to control the mosquito population. There is currently no effective vaccine against malaria.

A combination of antimalarial medication is recommended for both disease prevention and treatment of acute attacks. The combination used depends on many factors including disease severity, the species of malaria parasite causing the infection and the part of the world in which the infection was acquired, the latter two factors being taken into account as they affect the suitability of certain drugs due to issues with resistance.