Angiostrongylus costaricensis is a species of parasitic nematode and is the causative agent of abdominal angiostrongyliasis in humans.

[3] Infection of mammalian hosts occurs via ingestion of L3 larvae in mollusc tissue (e.g. undercooked or raw snails or accidentally on produce) or possibly food contaminated with slime containing such larvae.

In rats with heavy infestations there is a yellow discolouring of the surface of the intestinal walls.

Serology is sometimes used to diagnose from a blood sample and there are specific enzyme-linked immunosorbent assays (ELISA).

[4] Diagnosis is based primarily on detection of worms and/or eggs in biopsy specimens.