Malaria is an infectious disease, transmitted to humans by mosquitoes. Symptoms include fever, fatigue, headache, and vomiting. Severe cases of malaria may also include yellowish skin, seizures, coma, and may be fatal. Symptoms usually onset within ten to fifteen days of being bitten. Malaria is widespread in tropical and subtropical regions, but is easily preventable and treatable with modern medicine, despite there being no effective vaccine.
Malaria has been known throughout human history; the word itself is derived from the Italian mala aria, meaning "bad air." It was not until 1820 that quinine was developed as an effective treatment of malaria. Before then, most cases of malaria proved to be fatal. Quinine is still in use, often combined with other antimalarial medicines, although increasing drug resistance is proving to be problematic.
Sporozites enter the bloodstream via a mosquito bite, migrating to the liver. There, they multiply into merozoites before returning to the bloodstream. In the blood, these merozoites infect red blood cells. Malaria is then classified as either "severe" or "uncomplicated," depending upon symptoms. Uncomplicated malaria can be treated with oral medications, usually artemisins. Severe malaria must be treated with intravenous medications, as high fevers require the services of a critical care unit.