Chiejina S N, Fakae B B, Eze P I
Department of Veterinary Parasitology and Entomology, University of Nigeria, Nsukka.
Vet Res Commun. 1989;13(2):103-12. doi: 10.1007/BF00346720.
Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L3) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25 degrees C-30 degrees C and at a constant temperature of 50 degrees C and the free-living development was also monitored. L3 developed very readily in the faeces cultured at 25 degrees C-30 degrees C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50 degrees C died and disintegrated after 24-48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.
1982年10月至1983年4月期间，四块草地依次被含有已知数量主要为捻转血矛线虫和毛圆线虫未受精卵的山羊粪便污染。1987年2月至5月期间，另外四块草地同样被绵羊粪便污染。1987年2月至4月，还有一块草地被绵羊粪便反复污染。随后分别监测了粪便中自由生活阶段的虫口数量以及1983年4月底和1987年6月底牧草中感染性幼虫（L3）的数量。1987年2月和5月期间，将两份绵羊粪便对照培养物分别在25摄氏度至30摄氏度以及50摄氏度的恒温条件下在实验室中培养，并对自由生活阶段的发育情况进行监测。L3在25摄氏度至30摄氏度培养的粪便中以及在雨季末期10月铺在草地上的粪便中发育得非常快，但在雨季开始时5月污染的草地上发育得较少。在炎热干燥季节（12月至4月）沉积在草地上的粪便中的虫卵或在50摄氏度下培养的虫卵，在暴露于高温环境24至48小时后死亡并分解。结果表明，在尼日利亚衍生的稀树草原地区的旱季，绵羊和山羊的胃肠道线虫不太可能在开阔牧场上发育或存活。
