Mejer H, Roepstorff A
Danish Centre for Experimental Parasitology, Department of Veterinary Pathobiology, Royal Veterinary and Agricultural University, Dyrlaegevej 100, DK-1870 Frederiksberg C, Denmark.
Parasitology. 2006 Sep;133(Pt 3):305-12. doi: 10.1017/S0031182006000394. Epub 2006 Jun 2.
The transmission of Ascaris suum was studied in outdoor reared pigs. From May to June 2001, 6 farrowing paddocks were naturally contaminated with A. suum using experimentally infected seeder pigs. Early July, 1 sow farrowed on each paddock. One piglet per litter was slaughtered every second week starting at week 3 post-partum (p.p.) for registration of liver white spots and recovery of A. suum from the lungs and the small intestine. The last pigs were slaughtered at week 19 p.p. Faeces was examined for parasite eggs and blood was analysed for A. suum-specific antibodies. Weaning took place at week 7 p.p. by removing the sow. Paddock infection levels were estimated by regular examination of soil samples and in late June and late November using parasite naïve tracer pigs. Paddock contamination was high but eggs developed slowly resulting in a low initial transmission to the experimental pigs. By week 5 p.p. transmission had increased and the numbers of infective eggs in the soil increased during the study. The results indicate a continuous uptake of infective eggs, but visceral larval migration was reduced with time, probably due to the development of a pre-hepatic barrier. Nevertheless, a rather large population of adult worms remained in the pigs throughout the study, and it may primarily have been eggs ingested in the early infection phase that gave rise to the patent infections. It is suggested that neonatal exposure may result in increased persistence and size of adult worm burden and that the higher 'life-time worm burden' may be of significant economic importance.
在户外饲养的猪中研究了猪蛔虫的传播情况。2001年5月至6月，使用经实验感染的种猪对6个产仔围场进行了猪蛔虫的自然污染。7月初，每个围场有1头母猪产仔。从产后第3周开始，每隔一周从每窝仔猪中挑选1头进行屠宰，以记录肝脏白斑情况，并从肺和小肠中分离猪蛔虫。最后一批猪在产后第19周屠宰。对粪便进行寄生虫卵检查，并对血液进行猪蛔虫特异性抗体分析。在产后第7周通过移走母猪进行断奶。通过定期检查土壤样本以及在6月底和11月底使用未感染寄生虫的示踪猪来估计围场的感染水平。围场污染程度很高，但虫卵发育缓慢，导致对实验猪的初始传播率较低。到产后第5周，传播率有所增加，且在研究期间土壤中感染性虫卵的数量也有所增加。结果表明猪持续摄入感染性虫卵，但随着时间推移，内脏幼虫移行减少，这可能是由于肝前屏障的形成。尽管如此，在整个研究过程中猪体内仍有相当数量的成虫，可能主要是早期感染阶段摄入的虫卵导致了显性感染。研究表明，新生仔猪接触感染源可能会导致成虫负担的持续时间延长和数量增加，而较高的“终生蠕虫负担”可能具有重要的经济意义。
