Which protozoan parasite causes malaria and is responsible for the disease’s most severe cases?

Plasmodium falciparum is the protozoan parasite responsible for malaria’s most severe cases.

P. falciparum is transmitted to people through the bites of infected female Anopheles mosquitoes. It first develops in the liver and then infects red blood cells. Infected cells can adhere to small blood-vessel walls, contributing to complications such as cerebral malaria and severe anemia.

The parasite causes the largest share of malaria deaths worldwide, although the exact distribution changes with geography, prevention, diagnosis, and treatment. Plasmodium vivax is another major human malaria parasite, but P. falciparum is especially associated with life-threatening disease.

Malaria parasites are eukaryotic protists, not bacteria. Control relies on mosquito protection, testing, effective medicines, and vaccines or other preventive measures where recommended. Drug resistance remains an important public-health challenge.