DRY AREAS - AN EXAMPLE OF SEASONAL EVOLUTION OF HELMINTH INFECTION OFSHEEP AND GOATS IN SOUTHERN MAURITANIA

A total of 647 faecal. egg counts and 53 necropsies were performed on sheep and goats originating from three sites of a Sahelian region of M auritania (Gorgol) over a period of 2 years (1990-1992). Haemonchus co ntortus, Oesophagostomum columbianum and Stilesia globipunctata were t he most prevalent species. The seasonal pattern was characterized by l ong survival of adults and high percentages of arrested fourth-stage l arvae in the dry season, suggesting that two different strategies were used to survive from one rainy season to the next. Sheep and goats we re equally infected, except for Stilesia globipunctata, which was foun d more often in sheep. The influence of age was limited, although kids and lambs born in the beginning of the dry season did not become infe cted until their first grazing in the rainy season.