Tropical splenomegaly syndrome

Tropical splenomegaly syndrome, also known as hyperreactive malarial splenomegaly, occurs due to immunological overstimulation by repeated attacks of malarial infection over a long period of time. The condition is usually seen in areas where malaria is endemic, such as Africa and the Indian subcontinent.

Source: Wikipedia — Tropical splenomegaly syndrome (CC BY-SA 4.0)