Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Abstract

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.

Recovery of Trichostrongylus colubriformis infective larvae from three grass species contaminated in the autumn

“…In the dry regions of Africa, pastures can be considered safe three months after contamination (NDAMUKONG;NGONE, 1996). In Niger, pastures for sheep and goats can be considered free of contamination in the dry period (CHIEJINA et al, 1989). Similarly, in the semi-arid region of northeastern Brazil, the transmission of parasites is almost nil in dry periods (CHARLES, 1989).…”

Seasonal and habitat dependence of fleas parasitic on small mammals in Tanzania

“…One component of the parasite environment is represented by the hosts, whereas another component is the environment of the hosts, which influences parasites both directly (e.g. affecting their free-living transmission stages; Chiejina et al 1989;McSorley 2003;Carrillo et al 2007) and indirectly . In other words, the complicated nature of the environment of a parasite is determined by the fact that it has to deal with the host itself as well as with the host's biotic and abiotic environment.…”

A Review of the Epidemiology of Gastrointestinal Nematode Infections in Sheep and Goats in Ghana

“…The stocking rate in the forest zone is therefore an important factor in determining the level of challenge. Adult sheep and goats are capable of building up some resistance but young stock are very susceptible to gastrointestinal helminths (Assoku, 1981;Chiejina, 1986).…”

“…The prepatent period is normally 2-3 weeks, although it may be more than 6 months for certain species or if development is "arrested" (Michel, 1974;Eysker, 1993). Rainfall is considered to be the main climatic factor determining the availability of infective strongylid larvae and the transmission of infection in grazing animals (Chiejina et al, 1989;Fakae, 1990;Agyei & Amponsah, 2001;Agyei, 2003;Agyei et al, 2005). This paper reviews the epidemiological knowledge of gastrointestinal (GI) nematode infections in sheep and goats in the different agro-ecological zones of Ghana with the view to providing adequate information for developing strategic control measures against GI nematode infections in small ruminant in Ghana.…”