When you're bitten by a malaria-infected mosquito, the parasites that cause malaria are released into your blood and infect your liver cells. The parasite reproduces in the liver cells, which then burst open. This allows thousands of new parasites to enter the bloodstream and infect red blood cells. The parasites reproduce again in the blood cells, kill the blood cells, and then move to other uninfected blood cells.
After the early stages, life-threatening complications may develop rapidly with P. falciparum and P. knowlesi. If the infected person is not treated, serious complications or death can occur.
But you may recover in a week to a month (or longer) after being infected with P. vivax, P. malariae, or P. ovale, even without treatment.
Malaria can be a very serious disease for a pregnant woman and her developing fetus, for people without a spleen, and for young children. Medicine choices are limited for a pregnant woman or a child. Infection with P. falciparum can lead to death for a pregnant woman and her fetus. For these reasons, a pregnant woman should not travel to an area where she could get P. falciparum malaria. Visit the CDC website (www.cdc.gov/malaria/travelers/index.html) to find out whether malaria is a problem in the country where you will be traveling.
Malaria caused by P. falciparum may come back (recur) at irregular intervals for up to 2 years if treatment is not complete.
Malaria caused by P. vivax and P. ovale may recur at irregular intervals for up to 3 to 4 years, but medicine can prevent relapses.
P. malariae can remain in the blood of an infected person for more than 30 years, usually without causing any symptoms.