Rose R A, Behnke J M
Department of Zoology, University of Nottingham, University Park.
Parasitology. 1990 Jun;100 Pt 3:469-78. doi: 10.1017/s0031182000078781.
Neonatal hamsters were exposed to varying doses of Necator americanus larvae and changes in the stability of the resulting worm burdens were monitored over a period of 25 weeks. No change in worm burdens was evident for the first 5 weeks of infection, irrespective of the infection intensity, but the more heavily infected groups subsequently lost worms in a density-dependent manner. Male and female hamsters lost comparable proportions of their established parasite burdens indicating that there was no host sex-linked difference in this respect. By week 15 infections had stabilized and the residual worm burdens, usually a maximum of 30 worms survived for a considerably longer period of time. Initially the percentage of male worms varied from 45% to 50% but as infection progressed male worms comprised a significantly increasing proportion of the total worm burden. By week 25 the percentage of male worms was usually in excess of 60%. The growth of infected animals was not severely affected by N. americanus, even when heavy worm burdens established initially, but a significant effect was detected particularly in week 5, prior to worm loss, when the adult worms would have been feeding on intestinal tissues and causing blood loss for a period of about 2 weeks. The most severe depression in the packed cell volume was also recorded in week 5, indicating that anaemia had been initiated in infected hamsters. Whilst, the regulation of parasite burdens in weeks 5-10 post-infection may have resulted from host immunity, the persistence of the residual worm burdens, the marked density-dependent anaemia and the subtle effect on host weight, all reflected well-documented aspects of chronic human necatoriasis.
将新生仓鼠暴露于不同剂量的美洲板口线虫幼虫，并在25周的时间内监测由此产生的虫负荷稳定性变化。在感染的前5周，无论感染强度如何，虫负荷均无明显变化，但随后感染较重的组以密度依赖的方式出现虫体丢失。雄性和雌性仓鼠丢失的已建立的寄生虫负荷比例相当，表明在这方面不存在宿主性别相关差异。到第15周时感染已稳定，残留的虫负荷（通常最多30条虫）存活了相当长的时间。最初雄虫的比例在45%至50%之间，但随着感染的进展，雄虫在总虫负荷中所占比例显著增加。到第25周时，雄虫的比例通常超过60%。即使最初建立了较重的虫负荷，感染动物的生长也未受到美洲板口线虫的严重影响，但在第5周，尤其是在虫体丢失之前，检测到了显著影响，此时成虫一直在摄取肠道组织并导致失血约2周时间。在第5周时还记录到血细胞比容的最严重下降，表明感染的仓鼠已开始出现贫血。虽然感染后第5至10周寄生虫负荷的调节可能是宿主免疫所致，但残留虫负荷的持续存在、明显的密度依赖性贫血以及对宿主体重的细微影响，都反映了慢性人类板口线虫病的充分记录的方面。
