Malaria Incubation Period
In the case of malaria, the incubation period for the disease (the period between infection and the beginning of symptoms) typically lasts between 10 days to four weeks. In some cases, the malaria incubation period may be as short as seven days or as long as several years. Factors that affect the incubation period for malaria include the type of Plasmodium parasite responsible for the infection. When antimalarial drugs are used to prevent the spread of the disease, they may also increase the length of the malaria incubation period by weeks or months.
When a person becomes infected with one of the Plasmodium parasites that cause malaria, he or she will not feel sick immediately. The infected person may feel normal from seven days to several years after infection; however, inside his or her body, the malaria parasites are multiplying. The period between infection with the parasites that cause the disease and the beginning of malaria symptoms is called the malaria incubation period.
For most people, the malaria incubation period is between 10 days to four weeks after the bite from the infected Anopheles mosquito, although a person may feel ill as early as seven days after infection, or as late as several years later. The malaria incubation period will vary depending on the type of Plasmodium parasite responsible for the infection.
Plasmodium falciparum tends to have a shorter incubation period, while Plasmodium malariae tends to have a longer incubation period.
The other kinds of malaria, Plasmodium vivax and Plasmodium ovale, can have a much longer malaria incubation period. For these parasites, a proportion of them may begin to grow immediately in the liver and cause symptoms after the normal incubation period. The remaining portion may remain inactive ("dormant") in the liver for several months (and up to about four years) after a person is bitten by an infected mosquito. When these parasites come out of hibernation, begin multiplying and then invade red blood cells, the person will become sick again. These "sleeping" forms are the causes of the relapses seen with these two species.