Malaria Basics

Malaria is a life-threatening parasitic disease caused by Plasmodium species and transmitted to humans through the bite of an infected female Anopheles mosquito. Five Plasmodium species cause malaria in humans: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi. Of these, P. falciparum is the most virulent and causes the majority of malaria-related deaths worldwide, while P. vivax is the most geographically widespread. The life cycle of the malaria parasite involves two hosts: the mosquito (definitive host where sexual reproduction occurs) and the human (intermediate host where asexual reproduction occurs). When an infected female Anopheles mosquito bites a human, it injects sporozoites into the bloodstream. These sporozoites travel to the liver within 30 minutes and invade hepatocytes, where they undergo asexual multiplication (exo-erythrocytic schizogony) over 7 to 30 days, producing thousands of merozoites. P. vivax and P. ovale can also form dormant liver stages called hypnozoites, which can reactivate weeks to years later causing relapse -- this is a critical distinction because treatment of P. vivax and P. ovale requires primaquine to eliminate hypnozoites and prevent relapse. The...