Cattle Schistosomiasis Host parasite Interactions

Abstract

Schistosomiasis is a common parasitic infection in cattle in Africa and Asia. Although schistosomes may, under rare conditions favouring intensive transmission, act as important pathogens per se (Kulkarni et al. 1954; Van Wyk et al. 1974; Markovics et al. 1993), most infections in endemic areas occur at a subclinical level. It has however been established that high prevalence rates of subclinical infections cause significant losses due to long-term effects on animal growth and productivity and increased susceptibility to other parasitic or bacterial diseases (Dargie, 1980; Pitchford & Visser, 1982; McCauley et al. 1983, 1984). For that reason and in parallel with studies on species affecting man, schistosomes of veterinary concern have received considerable interest over the last thirty years. Detailed reviews on cattle schistosomiasis have been published (Hussein, 1973; Lawrence, 1978a; Christensen et al. 1983 ; Kumar & de Burbure, 1986; Taylor, 1987). It is therefore not the intention here to provide a comprehensive review on the subject but rather to summarize the information available on those particular aspects discussed later in this thesis.