Angiostrongyliasis cantonensis (eosinophilic meningitis, Alicata's disease)

Angiostrongyliasis is an infectious disease caused by nematode parasites of the genus Angiostrongylus. The rat lung worm Angiostrongylus cantonensis, primarily a parasite of rodents, is largely responsible for human cases of eosinophilic meningitis, or meningoencerphalitis, which occurs on many Pacific islands and in Southeast Asia. The disorder, which frequently occurs in epidemic extent, is caused by invasion of the central nervous system by developing larvae of the parasite. The infection is most frequently due to ingestion of food containing the infective, third-state, larvae. Meningitic and ocular forms of the disease have been recognized. The disease has been described or referred to under a variety of synonyms. The terms eosinophilic meningitis, eosinophilic meningoencephalitis, and epidemic eosinophilic meningitis were first used to describe the disease before its etiology was known. These terms, however, lack specificity, because the eosinophilic meningitic syndrome may accompany many other parasitic as well as nonparasitic diseases of the central nervous system. Nevertheless, they are still being widely used, since in most cases only the epidemiology of the disease points to the etiologic role of A. cantonensis. Direct clinical or laboratory evidence of the etiologic agent is usually not established because reliable tests are not yet available. The term angiostrongylosis, or angiostrongyliasis, if used without the adjective, also may give rise to confusion, since the same term is applied to the pulmonary infection of dogs by A. vasorum and might be used for infection by any other Angiostrongylus species. Even the term cerebral or ocular angiostrongyliasis may prove in the future to have similar disadvantages. The scientifically correct term angiostrongyliasis cantonensis has been used recently. It is sufficiently specific and formed in analogy to the names of other parasitic diseases of man, like schistosomiasis japonica, schistosomiasis mansoni, schistosomiasis haematobia. For the murine infection, as well as for the disease produced experimentally in animals, the term angiostrongylosis cantonensis ought to be reserved because of the preferential use by veterinarians of the ending osis for designation of pathological changes produced in animals by parasites. After the recent discovery of A. costaricensis, another rat parasite causing human disease in Costa Rica, it becomes necessary to distinguish between angiostrongyliasis cantonensis (eosinophilic meningitis) and angiostrongyliasis costaricensis (intra-abdominal eosinophilic granulomatosis). A potential disadvantage of these terms may be encountered in case of a systemic revision or reclassification of the parasite. This has happened at intervals. A. cantonensis was named Pulmonema cantonensis by its discoverer and later was described under the name Haemostrongylus ratti.