The infection is initiated when sporozoites are injected with the saliva of a feeding mosquito.
Sporozoites are carried by the circulatory system to the liver and invade hepatocytes (1). The
intracellular parasite undergoes an asexual replication known as exoerythrocytic schizogony
within the hepatocyte (2-4). Exoerythrocytic schizogony culminates in the production of
merozoites which are released into the bloodstream (5). A proportion of the liver-stage parasites
from P. vivax and P. ovale go through a dormant period (not shown) instead of immediately
undergoing asexual replication (i.e., stay temporarily at step 2). These hypnozoites will
reactivate several weeks to months (or years) after the primary infection and are responsible for
relapses.