Angiostrongyliasis is a zoonotic disease resulting from infection with two species of a parasitic nematode (roundworm), Angiostrongylus cantonensis (also known as rat lungworm) and Angiostrongylus costaricensis. The predominant clinical manifestations in humans are eosinophilic meningitis for A. cantonensis and enteritis for A. costaricensis. This summary focuses on angiostrongyliasis resulting from infection with A. costaricensis.

Angiostrongyliasis costaricensis has been reported mostly in South and Central America, the Caribbean, and Africa.

The life cycle is similar for both species. In the definite host (rats), adult worms lay eggs, and larvae hatch from them, migrate, and get excreted in the rat's feces. These larvae are then swallowed by snails and slugs. These slugs may then be eaten by a variety of creatures including frogs, crabs, fish, etc. The predominant manner in which humans become infected is ingestion of raw snails that are harboring the larva. Similarly, ingestion of other uncooked or undercooked freshwater species that have consumed infected snails or slugs such as frogs, shrimp, crabs, and fish can also lead to disease. Fruits and vegetables can also carry larvae and cause infection. Children may infect themselves by putting their hands in their mouth after playing with affected creatures.

Angiostrongylus costaricensis causes eosinophilic enteritis, usually in children. Since the worms often reside in the arterioles of the ileocecal region, the infection is often discovered during surgery in cases of suspected appendicitis. The worms are typically removed at the time of surgery.