occurs when a female Anopheles mosquito injects sporozoites while
taking a blood meal.
spozoites move to the liver, enter liver cells and replicate asexually
through schizogony. This is the exoerythrocytic stage.
Merozoites from the liver infect red blood cells and replicate asexually
through schizogony. This is the erythrocytic stage.
Merozoites continue to burst from RBCs and infect new RBCs in a periodic
cycle of 48-72 hours depending on the species.
Some parasites will differentiate into the sexual stages, called gametocytes.
The life cycle is continued when an Anopheles mosquito ingests gametocytes
during a blood meal.
Infection with Plasmodium
species leads to chracteristic fever and chills, often accompanied by headaches,
muscle soreness, weakness, vomiting and diarrhea.
Other symptoms include an enlarged
spleen, anemia, lung or kidney dysfunction and neurological problems.
Infection with Plasmodium falciparum
is often the most severe and involves infection in the brain (cerebral
malaria), kidney failure, and severe anemia that may lead to death.
Infection with P. vivax often leads to complications of the spleen
or spleen rupture.
A dormant stage of P. ovale
and P. vivax may remain in the liver for weeks or years after the
intial infection. These parasites may then enter the bloodstream
and cause relapses long afterwards.