The life history of the rat lung-worm, Angiostrongylus cantonensis (Chen) (Nematoda: Metastrongylidae).

Abstract

Adult Angiostrongylus cantonensis live in the pulmonary arteries. Unsegmented ova are discharged into the blood stream, and lodge as emboli in the smaller vessels. First-stage larvae break through into the respiratory tract, migrate up the trachea, and eventually pass out of the body in the faeces. Slugs (Agriolimax laevis) act as intermediate hosts. Two moults occur in the slug, and third-stage larvae appear about the 17th day. The larvae remain within the two cast skins until freed in the stomach of the rat by digestion. They then pass quickly along the small intestine as far as the lower ileum, where they leave the gut and become blood-borne. They congregate in the central nervous system, and have been found there 17 hr after ingestion. The anterior portion of the cerebrum is the most favoured site, and here the third moult takes place on the sixth or seventh day and the final one between the 11th and 13th days. Young adults emerge on the surface of the brain from the 12th to 14th day, and spend the next 2 weeks in the subarachnoid space. From the 28th to 31st days they migrate to the lungs via the venous system, passing through the right side of the heart to their definitive site in the pulmonary arteries. The prepatent period in the rat usually lies between 42 and 45 days.