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In vitro demonstration of in utero larval development in an oviparous parasitic nematode: Haemonchus contortus

Published online by Cambridge University Press:  06 April 2009

Liyew Ayalew
Affiliation:
Reproductive Physiology Unit, Montreal General Hospital and the Departments of Medicine, Obstetrics and Gynecology, and Psychiatry, McGill University, Montreal
Beverley E. Pearson Murphy*
Affiliation:
Reproductive Physiology Unit, Montreal General Hospital and the Departments of Medicine, Obstetrics and Gynecology, and Psychiatry, McGill University, Montreal
*
*Address corresspondence to: Dr B. E. Pearson Murphy, Monteal General Hospital, Room 7823, LH, 1650 Cedar Avenue, Montreal, Canada H3G 1A4.

Summary

The life-cycle of Haemonchus contortus, a pathogenic stomach nematode of sheep, is typical of those of the other members of the superfamily Trichostrongyloides, all of which require a period of development outside the definitive host. Classically, gravid H. contortus, known as strictly oviparous, releases her eggs into the abomasal lumen. The eggs are passed out in the faeces in which they hatch into the 1st-stage larvae and then develop into the infective 3rd-stage larvae. We have developed a method to study the fate of eggs within gravid worms. Using this procedure, we have shown that H. contortus may also exhibit viviparity with apparently normal development from the egg to the 4th larval stage taking place within the gravid female maintained in vitro. On the basis of these observations we speculate that viviparity might occur in vivo with consequent autoinfections; if so, this might explain some puzzling clinical and epidemiological features of haemonchosis, as well as the incomplete efficacy of current control measures.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1986

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