Plasmodium falciparum is a unicellular protozoan parasite that infects humans and causes the most severe and deadly form of malaria. The parasite is transmitted to humans by the bite of infected female Anopheles mosquitoes and undergoes complex cycles of development in liver cells and red blood cells.
Life cycle and pathogenic features
Plasmodium falciparum belongs to the phylum Apicomplexa. When an infected mosquito feeds, it injects sporozoites that rapidly invade hepatocytes. After a period of liver multiplication (exoerythrocytic stage), thousands of merozoites are released into the bloodstream, where they invade red blood cells. Inside erythrocytes the parasite goes through ring, trophozoite and schizont stages, producing more merozoites that rupture the host cell. Some asexual parasites differentiate into sexual gametocytes, which can infect another mosquito. Unlike other human malaria species, P. falciparum can invade red cells of all ages, leading to high levels of parasitemia. The parasite modifies the surface of infected erythrocytes by expressing proteins such as PfEMP1 that mediate cytoadherence to capillary endothelium and cause sequestration in organs. This cytoadherence contributes to severe complications such as cerebral malaria and placental malaria. P. falciparum has a genome of approximately 23 megabases and expresses unique organelles such as the apicoplast. Drug resistance mutations in genes encoding enzymes and transporters have led to resistance to chloroquine and other antimalarials.
Clinical impact and key facts
P. falciparum is prevalent in tropical and subtropical regions, especially sub Saharan Africa, where it causes the majority of malaria deaths. Symptoms include periodic fever, chills, severe anemia, jaundice and, in complicated cases, impaired consciousness, respiratory distress, acidosis and renal failure. Cerebral malaria arises when infected erythrocytes sequester in brain microvasculature, leading to coma and high mortality. Pregnant women are at risk of placental malaria, which can result in low birth weight and fetal loss. Prevention relies on vector control measures such as insecticide treated bed nets and indoor residual spraying, as well as chemoprophylaxis for travellers. Artemisinin based combination therapies are currently the mainstay of treatment, but emerging resistance underscores the need for ongoing surveillance and new therapeutics. Research into vaccine candidates, including pre erythrocytic and blood‑stage antigens, is ongoing to reduce the burden of this parasite.
Plasmodium falciparum is a highly adapted malaria parasite that causes substantial morbidity and mortality worldwide. Its ability to invade red blood cells of any age and to sequester in tissues contributes to its virulence. Understanding its biology and life cycle informs efforts to control and treat falciparum malaria.
Related Terms: Malaria, Sporozoite, Anopheles, Cerebral malaria, Hemozoin