Malarial parasites in humans are protozoa of the genus Plasmodium: Plasmodium falciparum, P. vivax, P. ovale, P. malariae and the zoonotic P. knowlesi. P. falciparum causes the most severe disease; P. vivax and P. ovale can form dormant liver stages (hypnozoites) causing relapses. Transmission is by infected Anopheles mosquitoes. Prompt diagnosis and treatment are important.

The four malaria parasites that commonly infect humans are Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale. P. falciparum causes the most severe illness; P. vivax and P. ovale can form dormant liver stages (hypnozoites) causing relapses, while P. malariae typically causes milder, often long‑lasting infections. All are transmitted by female Anopheles mosquitoes and vary by region and treatment needs.

Five Plasmodium species cause malaria in humans: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi. P. falciparum causes the most severe disease; P. vivax and P. ovale can form dormant liver stages (hypnozoites) leading to relapses; P. knowlesi is a zoonotic species primarily from macaques, and P. malariae is typically milder.

The malaria parasite is a single-celled protozoan of the genus Plasmodium (notably P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi) transmitted to humans by infected female Anopheles mosquitoes. It infects liver cells and red blood cells, causing fever, chills and anemia, and can cause severe complications. Diagnosis uses blood smears or rapid tests; treatment is with antimalarial drugs.

Malaria is caused by Plasmodium parasites transmitted to humans through the bite of infected female Anopheles mosquitoes. Key human species include P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi; P. falciparum most often causes severe disease. Less commonly, malaria spreads via infected blood transfusion, contaminated needles, or mother-to-child transmission during pregnancy.

Malaria is identified primarily by blood tests: microscopy of thick and thin blood smears to visualize parasites inside red blood cells (ring forms, trophozoites, schizonts, gametocytes), with thick smears for sensitivity and thin smears for species and parasite count. Rapid diagnostic tests detect Plasmodium antigens for point-of-care use. PCR confirms species and detects low-level infections. Clinical signs and travel history guide testing.