Christensen C M, Barnes E H, Nansen P, Roepstorff A, Slotved H C
Danish Centre for Experimental Parasitology, Royal Veterinary and Agricultural University, Frederiksberg C. Copenhagen, Denmark.
Int J Parasitol. 1995 Dec;25(12):1491-8. doi: 10.1016/0020-7519(95)00085-2.
This report describes the effect of different dose levels of infection upon worm burdens and development and fecundity of the parasites. Three groups each of 40, 9-week-old, helminth naive pigs were inoculated once with either 2000 (group A), 20,000 (group B), or 200,000 (group C) infective third stage larvae of Oesophagostomum dentatum. Subgroups of 5 pigs from each major group were killed 3, 6, 11, 14, 18, 25, 34 and 47 days post inoculation (p.i.) and the large intestinal worm burdens were determined. Faecal egg counts were determined at frequent intervals after day 13 p.i. There were no overt clinical signs of gastrointestinal helminthosis during the experiment. Faecal egg counts became positive in groups A and B at around day 19 p.i., whereas most pigs in the high dose group C did not have positive egg counts until day 27-33 p.i. and some pigs remained with zero egg counts until the end of the study. Throughout the experiment the worm populations in group C consisted mainly of immature larval stages, while those in groups A and B were predominantly adult stages after days 14-18. Adult worms from the low dose group A were significantly longer than those from group C. At high population densities, stunted development of worms and reduced fecundity among female worms were found. Furthermore, there was a tendency for the distribution of the worms within the intestine to be altered with increasing population size.
本报告描述了不同感染剂量对蠕虫负荷以及寄生虫发育和繁殖力的影响。将三组各40头9周龄未感染蠕虫的仔猪，每组分别接种2000条（A组）、20000条（B组）或200000条（C组）有齿食道口线虫感染性第三期幼虫。在接种后3、6、11、14、18、25、34和47天，从每个主要组中选取5头猪的亚组进行宰杀，并测定大肠蠕虫负荷。在接种后第13天之后定期测定粪便虫卵计数。实验期间未出现明显的胃肠道蠕虫病临床症状。A组和B组在接种后约第19天粪便虫卵计数呈阳性，而高剂量C组的大多数猪直到接种后第27 - 33天才出现阳性虫卵计数，一些猪直到研究结束时虫卵计数仍为零。在整个实验过程中，C组的蠕虫种群主要由未成熟幼虫阶段组成，而A组和B组在第14 - 18天后主要为成虫阶段。低剂量A组的成虫比C组的成虫长得显著更长。在高种群密度下，发现蠕虫发育受阻，雌虫繁殖力降低。此外，随着种群规模的增加，蠕虫在肠道内的分布有改变的趋势。
