liverstage

Liver stage refers to the phase of the malaria parasite life cycle that occurs in hepatocytes after transmission by a mosquito bite. Sporozoites injected into the skin enter the bloodstream and rapidly migrate to the liver, where they invade liver cells and begin replication. In hepatocytes they develop into exoerythrocytic schizonts, which release merozoites into the bloodstream to begin the red blood cell—infecting, or erythrocytic, stage of the parasite life cycle. This liver stage is typically asymptomatic, and clinical symptoms arise after merozoites invade red blood cells.

In Plasmodium falciparum, the liver stage generally lasts about 6–7 days before merozoites are released. In Plasmodium vivax and Plasmodium ovale, there is an additional feature: dormant liver forms called hypnozoites that can persist for weeks or months and reactivate later to cause relapses, even after a person has finished a course of treatment for the blood-stage infection.

Because the liver stage is asymptomatic, it is a key target for malaria prevention. Vaccines aiming to block sporozoite entry into hepatocytes or to destroy infected liver cells, as well as chemoprophylaxis that eliminates sporozoites, are designed to interrupt this stage. Understanding the liver stage is important for explaining malaria pathogenesis, transmission dynamics, and the development of interventions that prevent progression to the symptomatic blood stage.