Angiostrongyliasis is the most common cause of eosinophilic meningitis in SE Asia and Pacific Basin.
it is caused by Angiostrongylus cantonensis, a nematode (roundworm) parasite which resides in pulmonary arteries of rats.
primary intermediate host are snails
humans are incidental hosts and become infected through eating raw or undercooked infected snails or other vectors, or contaminated water or vegetables.
the larva migrate to CNS where they cause eosinophilic meningitis