Which malaria species is associated with high fever and release of merozoites from red blood cells, contributing to severe disease?

• A. Plasmodium vivax
• B. Plasmodium ovale
• C. Plasmodium falciparum
• D. Plasmodium malariae

Answer: (C)

High fever in malaria comes from the rupture of infected red blood cells (schizogony) and release of merozoites into the bloodstream. The species most associated with severe disease is the one whose infected red blood cells stick to the lining of blood vessels and accumulate in the microvasculature. This cytoadherence causes microvascular obstruction, tissue hypoxia, and organ damage, leading to life-threatening syndromes like cerebral malaria. Plasmodium falciparum has the ability to infect red blood cells of all ages, reach very high parasite burdens, and mediate this vascular sequestration, making it the primary cause of severe malaria.

The other species tend to produce fever patterns tied to their schizogony cycles and are generally less likely to cause the same degree of severe vascular complications (vivax and ovale cause relapses related to liver-stage hypnozoites and are usually milder; malariae causes a slower quartan fever with lower parasitemia).