Abstract
Observations from October 1965 to May 1967, on the role played by mollusks and other invertebrates in the transmission of Angiostrongylus cantonensis infection to man on the South Pacific island of New Caledonia revealed that various snails, slugs and a planarian, ocurring in gardens supplying considerable amounts of edible green vegetation to local markets, were commonly infected with third-stage larvae of A. cantonensis. The veronicellid slugs, Vaginulus plebeius and Laevicaulus alte, were the most frequently and intensively infected mollusks and they probably serve as the chief reservoir of infection for feral rats. The high level of infection in these slugs not only results in maintaining a large population of infected rats but is of importance in the dispersal of infective larvae into planarians serving as paratenic hosts for the parasite. There is no apparent seasonal diference in the rate and level of infection among the slugs, although they have a dormant period during the cooler months (July to September) of the year. It is suggested that planarians are probably the single most important source of human infection in New Caledonia. The planarians show a marked seasonal occurrence, reaching their peak during the cool months of the year, which corresponds to the peak vegetable growing season. Their highly carnivorous habits in their attacking of both snails and slugs results in a high level of infection although individual planarians harbor relatively low numbers of larvae, usually less than 10. Their small size, their ability to fragment easily, and their rapid dehydration to form inconspicuous black masses contaminating lettuce and other vegetables make them an ideal vehicle for the transmission of A. cantonensis to man.
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Copyright (c) 1976 Revista de Biología Tropical