Pathological findings in four cases of human angiostrongyliasis

Three adults and a 3 1/2-year-old child presented with eosinophilic meningitis. A history of consumption of raw snails was elicited in 2; evidence of a constant diet of raw food, in the form of opisthorchiasis and taeniasis, as well as angiostrongyliasis, was present in the third; no history of raw food ingestion was obtained in the fourth, the child. Pathologic changes were similar in all 4 cases. There was infiltration of the meninges and around intracerebral vessels by varying proportions of lymphocytes, plasma cells and eosinophils. Numerous tracks and microcavities were found in the brains, and in the spinal cords in 2 cases, varying in size from 0.1 to 2 mm, and in age, with older tracks containing debris and gitter cells, newer tracks showing disruption of brain tissue, with and without haemorrhage. Numerous 4th and 5th stage Angiostrongylus larvae, alive and dead, were found in the meninges and brain tissue, sometimes in blood vessels or perivascular spaces, in 3 cases; in the fourth case a 5th stage larva was found on the surface of the right frontal lobe. In one case a degenerating larva was found in a pulmonary vessel. Cellular reaction was more often associated with dead larvae.