The Brief Case: Angiostrongylus cantonensis Eosinophilic Meningitis in a Returned Traveler

摘要

Eosinophilic meningitis is a rare, underrecognized clinical entity with a distinct differential diagnosis. It is defined by the presence of ≥10% eosinophils/μl of the total CSF leukocytes and thus can easily be missed if it is not the predominant cell type. One of the most common causes of eosinophilic meningitis, Angiostrongylus cantonensis, is the rat lungworm first described in 1935 by H. T. Chen, who named it after Canton, China, where it was recovered. The adult worms inhabit and lay eggs within the pulmonary arteries of a variety of rodents. Once hatching occurs, the first-stage (L1) larvae enter the alveolar space, migrate up the trachea and down the alimentary tract, and finally are excreted in the feces. Slugs, as well as land planarians and terrestrial and aquatic snails, serve as the intermediate hosts, either by L1 larval penetration into the mollusk or by the ingestion of contaminated rodent feces. Larval development continues within the mollusk, where the third-stage (L3) infective larvae develop. Following ingestion by rodents, the L3 larvae migrate to the brain, where they develop into young adults before migrating to the subarachnoid space. From there the young adult enters the venous system and finally undergoes sexual maturation within the pulmonary arteries. Humans serve as an accidental host and thus develop infection through ingestion of slugs, snails, land planarians on vegetables contaminated with infective larvae, or paratenic hosts, such as crabs or shrimp. Larvae are unlikely to survive within humans, and most will die in the central nervous system (CNS). Some larvae may reach the eye chamber; however, they are unlikely to migrate to the lungs.