Epidemiology:
(1) Most cases are acquired in Southeast Asia and the Pacific basin (including Japan, Hawaii, Philippines, Papua New Guinea).
(2) Rats carried in ships have dispersed the parasite to Australia, North America and other regions.
(3) Transmission to humans may occur by consuming third-stage larvae, by (a) eating raw snails, (b) fresh vegetables contaminated with mollusk slime. or (c) crabs or freshwater shrimp that have eaten infected mollusks.
Clinical Features:
(1) subacute meningitis, with fever, headache, photophobia and paresthesias
(2) CSF eosinophilia (usually > 10%), with normal CSF glucose and slight increase in CSF protein
(3) absence of mass lesions on CT or MRI scans of the brain.
Laboratory Diagnosis:
(1) positive serology (ELISA, confirmed by Western blot), with a 31-kDa antigen considered more specific
(2) direct visualization of worm or larvae
Differential diagnosis (pages e113-e114):
(1) gnathostomiasis
(2) schistosomiasis
(3) toxocariasis
(4) neurocysticercosis
(5) baylisascariasis
(6) trichinosis
(7) paragonimiasis
(8) coccidioidomycosis
(9) neurosyphilis
(10) malignant lymphoma
(11) hypereosinophilic syndrome
