Short report: Schistosoma mansoni miracidia are killed by the defense system of an Argentine strain of Biomphalaria straminea.

L Grassi Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.

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M Torr es Jordá Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.

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Z Andrade Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.

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S M González Cappa Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.

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DOI:
https://doi.org/10.4269/ajtmh.2001.65.290
Volume/Issue:
Volume 65: Issue 4
Page(s):
290–292
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Biomphalaria straminea snails from Argentina fail to shed cercariae even if exposed to high doses of Schistosoma mansoni EC miracidia. Alternative explanations for this failure are that miracidia are unable to penetrate the snail's epithelium or that the miracidia are killed by the snail's defense system. To discriminate between these 2 possibilities, B. straminea snails were individually exposed to increasing doses of miracidia. Susceptible B. glabrata were used as controls. Exposed snails were fixed 12 hr after exposure, and histological sections of the whole specimens were examined. Miracidia were seen to penetrate the epithelium of B. straminea and B. glabrata at similar rates (14.7%), independent of the exposure level. Regardless of the miracidial dose, 94% of the penetrating miracidia appeared encapsulated by the B. straminea defense system, whereas in B. glabrata, only 42% of the miracidia underwent encapsulation. These results show that resistance of B. straminea to S. mansoni EC strain is due to an efficient defense system that destroys miracidia once they have penetrated.

Author Notes

Published Online:
Oct 2001
Cover The American Journal of Tropical Medicine and Hygiene
The American Journal of Tropical Medicine and Hygiene
Print ISSN:
0002-9637
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