Nematodirus infestation in lambs: the importance of prepatent infestation in the stimulation of resistance

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Abstract
Extract Stewart (1959) Brunsdon, R. V. 1960. N.Z. J. agric. Res., 3: 772–772. [Taylor & Francis Online] [Google Scholar] has reviewed the literature relating to the mechanisms of resistance of the host to nematode infestation. Living parasites or antigenic materials produced from them seem to be essential for the stimulation of a satisfactory resistance; and the developmental stages would appear to be more important immunologically than the adult parasites. Most of the immunological studies of trichostrongyle parasites of the alimentary tract of sheep have concerned Haemonchus contortus. Stoll (1942) Brunsdon, R. V. 1962. N.Z. vet. J., 10: 1–1. [Taylor & Francis Online] [Google Scholar] reported that he was able to induce resistance by injecting intraperitoneally or subcutaneously sterilized exsheathed infective H. contortus larvae. Recently, Soulsby and Stewart (1960) Brunsdon, R. V. 1963. N.Z. J. agric. Res., in press [Google Scholar] have shown that the self-cure reaction in H. contortus infestations of sheep is provoked by antigens liberated from worms during their third ecdysis. Silverman and Patterson (1960) Ewer, T. K. and Sinclair, D. P. 1951. N.Z. J. Sci. Tech., 32A: 35–35. [Google Scholar] found that the fourth and fifth larval stages were significantly more antigenic than the third-stage larvae. Mulligan et al. (1961) Mulligan, W. , Gordon, H. McL. , Stewart, D. F. and Wagland, B. M. 1961. Aust. J. agric. Res., 12: 1175–1175. [Google Scholar] demonstrated that a high proportion of lambs dosed with irradiated infective larvae of Haenzomhcs contortus and Trichosfroyylw colubriformis, respectively, exhibited a solid resistance to a challenge infection.