Why does malaria cause repeating cycles of chills and fever?

Malaria causes repeating cycles of chills and fever due to the synchronized life cycle of the Plasmodium parasite within the human body.

After infecting red blood cells, the parasites multiply rapidly. The periodic chill-and-fever attacks occur when these infected blood cells rupture, releasing a new generation of merozoites and toxins into the bloodstream.12

The timing of these symptoms depends on the specific species of the parasite:
* 48-hour cycles (tertian malaria): Caused by P. falciparum, P. vivax, and P. ovale.12
* 72-hour cycles (quartan malaria): Caused by P. malariae.12
* 24-hour cycles: Caused by P. knowlesi, which can result in daily fever spikes.12

Each attack typically lasts 4 to 10 hours, progressing through stages of shaking chills, high fever with headache, and finally profuse sweating as the body temperature returns to normal. If a patient is infected with multiple generations of parasites or different species simultaneously, these classic patterns may become irregular.2