The persistence and fate of inhibited Haemonchus contortus larvae in young sheep.

Abstract

Abstract Extract Inhibited development of Haemonchus contortus at an early fourth larval stage has been reported frequently both in New Zealand (McKenna, 1973a McKenna, P. B. 1973a. The significance of inhibition in the parasitic development of abomasal nematodes in New Zealand sheep. N.Z. vet. J., 21: 98–102. [Taylor & Francis Online] , [Google Scholar]; Brunsdon, 1973 Blitz, N. M. and Gibbs, H. C. 1971a. An observation on the maturation of arrested Haemonchus contortus larvae in sheep. Can. J. comp. Med., 35: 178–180. [Google Scholar]) and elsewhere (Muller, 1968 Blitz, N. M. and Gibbs, H. C. 1971b. Morphological characterization of the stage of arrested development of Haemonchus contortus in sheep. Can. J. Zool., 49: 991–995. [Crossref], [Web of Science ®] , [Google Scholar]; Connan, 1968 Blitz, N. M. and Gibbs, H. C. 1972a. Studies on the arrested development of Haemonchus contortus in sheep. I. The induction of arrested development. Int. J. Parasitol, 2: 5–12. [Google Scholar], 1971 Blitz, N. M. and Gibbs, H. C. 1972b. Studies on the arrested development of Haemonchus contortus in sheep. II. Termination of arrested development and the spring rise phenomenon. Int. J. Parasitol, 2: 13–22. [Crossref] , [Google Scholar]; Blitz and Gibbs, 1972a Brunsdon, R. V. 1973. Inhibited development of Haemonchus contortus in naturally acquired infections in sheep. N.Z. vet. J., 21: 125–126. [Taylor & Francis Online] , [Google Scholar], b Connan, R. M. 1968. Studies on the worm populations in the alimentary tract of breeding ewes. J. Helminth., 42: 9–28. [Crossref], [PubMed] , [Google Scholar]; Ayalew and Gibbs, 1973 Connan, R. M. 1971. The seasonal incidence of inhibition of development of Haemonchus contortus. Res. vet. Sci., 12: 272–274. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) and although it is generally accepted that such larvae are capable of eventual resumption of development (Blitz and Gibbs, 1971a Field, A. C., Brambell, M. R. and Campbell, J. A. 1960. Spring rise in faecal worm-egg counts of housed sheep, and its importance in nutritional experiments. Parasitology, 50: 387–399. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), relatively little is known regarding their persistence in sheep.