What Causes Malaria: How the Plasmodium Parasite Infects People

Neither. Malaria is caused by a single-celled parasite called Plasmodium, technically a protozoan, one of the oldest kinds of life on earth. Five species infect humans: P. falciparum (the most dangerous, common in Africa and parts of India's North-East and eastern states), P. vivax (the most widespread in India, causes relapsing infections), P. ovale, P. malariae, and P. knowlesi (rare, mainly South-East Asian forest exposure). Because it is a parasite and not a bacterium or virus, malaria does not respond to antibiotics or antiviral medicines. It needs specific antimalarial drugs, chloroquine, artemisinin-based combinations, or primaquine, depending on the species and drug-resistance pattern in the region.

The bite injects fewer than a hundred parasite sporozoites into your bloodstream, a tiny number, but they head straight for the liver within an hour. Inside a liver cell, each sporozoite multiplies silently over 7-30 days into tens of thousands of new parasites (merozoites). When the liver cell bursts, those merozoites flood into your bloodstream and start invading red blood cells. Each infected red cell then bursts every 48-72 hours, releasing more parasites, and this is when you first feel sick. So the mosquito bite is small, but the liver stage is a hidden multiplier that turns a handful of parasites into millions before symptoms even begin.

Because the parasite's blood-stage cycle is synchronised. All the infected red blood cells burst at roughly the same time, every 48 hours for P. vivax and P. ovale (tertian fever), 48 hours for P. falciparum (though often less regular), and 72 hours for P. malariae (quartan fever). Each mass rupture releases parasites plus toxic parasite waste products into the bloodstream, which triggers the immune system to spike fever, chills, and shivering, the classic malaria paroxysm. Between paroxysms, the parasite is quietly invading fresh red blood cells and you feel relatively normal. This cyclical pattern is so distinctive that a fever every other day in someone who has been in an endemic area should trigger a malaria test even before other symptoms develop.

Both P. falciparum and P. vivax are prevalent in India but they behave differently. P. falciparum is more common in Odisha, Chhattisgarh, Jharkhand, and the North-East and causes almost all severe and fatal malaria, cerebral malaria, kidney failure, ARDS, severe anaemia. It progresses fast and can kill within days if untreated. P. vivax is more widespread across the country and causes fewer deaths but has two features that matter: relapses can occur months to years after the original infection because dormant liver-stage parasites (hypnozoites) can reactivate, and chronic P. vivax weakens people over time. Any fever after being in a mosquito-endemic area should be tested regardless of which species is more common there, waiting to see if it is just viral fever can be dangerous with P. falciparum.