Abstract
The authors present a survey of gastrointestinal helminths of sheep on permanent pastures in the extreme north region of Tunisia (Mediterranean climate). Dynamic infestation of animals has been monitored by using batches of three tracer lambs introduced each two months during 2004 and 2005. These lambs were kept in the pens of veterinary school of Sidi Thabet (Tunisia) during three months and then necropsied. Faecal and blood samples were took from tracer lambs each two months during the whole period, and from animal flock only during 2004. The main helminth genera encountered were Trichostrongylus spp., Teladorsagia spp., Strongyloides papillosus and Anoplocephalidea; occasionaly were found Nematodirus, Oesophagostomum, Chabertia, Cooperia, Trichuris and Paramphistomum. The egg count of the ewes and lambs in the flock showed two peaks. For both ewes and lambs there is a gradual increase from January with a peak in May-June. This first peak is considered to be due to acquisition of infective larvae during the rainy and cold season, as evident from the worm burdens of tracer lambs. The second peak was exclusively observed in ewes during late autumn-early winter (November-December); it has two origins: infestation by third larvae stage and the periparturient rise. The worm burdens of tracer lambs showed that there was a gradual accumulation of nematodes from September- October, reaching a peak in March-April; a very low or naught infection is reported during the dry period (July-August). Infection by Anoplocephalidea was higher during the dry season. This study is primordial for a comprehensive control programme implementation against gastrointestinal helminths.
Highlights
Small ruminant industry plays a significant role in food security and as an income source for many resource-poor families in most developing countries
The importance of knowledge of the seasonal population trends and availability of exogenous stages of sheep helminths for design control programmes has been well documented in other countries (Armour, 1980; Brunsdon, 1980; Katerina et al, 2009)
Each stage of the gastrointestinal exogenic phase is conditioned by climatic factors, specially temperature and humidity which determine both activity and viability of exogenous stages conditioning the epidemiological feature of gastrointestinal helminthiases
Summary
Small ruminant industry plays a significant role in food security and as an income source for many resource-poor families in most developing countries. & DARGHOUTH M.A. bad quality products leading to a dramatic increased of production costs (Waller, 1997; Perry & Randolph, 1999). Bad quality products leading to a dramatic increased of production costs (Waller, 1997; Perry & Randolph, 1999) The control of these infestations needs an excellent knowledge of their epidemiological features and requires important and persistent expenses (Michel, 1976, 1985; Armour, 1980). That is why we emphasise the need for relevant epidemiological data to design and implement rational preventive programmes against sheep helminthiasis in the studied region. The importance of knowledge of the seasonal population trends and availability of exogenous stages of sheep helminths for design control programmes has been well documented in other countries (Armour, 1980; Brunsdon, 1980; Katerina et al, 2009). Each stage of the gastrointestinal exogenic phase is conditioned by climatic factors, specially temperature and humidity which determine both activity and viability of exogenous stages conditioning the epidemiological feature of gastrointestinal helminthiases
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