Epidemiology of gastrointestinal helminths of sheep in the Rabat area of Morocco.

The epidemiology of gastrointestinal helminths of sheep on permanent pastures in Morocco was studied by monthly examination of faeces of ewes for helminth eggs and by use of batches of 3 tracer lambs each month from December 1979 to November 1980. The main helminth genera encountered were Teladorsagia, Haemonchus, Trichostrongylus and Moniezia, with Nematodirus, Cooperia, Oesophagostomum and Trichuris occasionally recorded. The faecal egg counts of ewes showed 2 peaks; the first in March due to the acquisition of larvae during the rainy season and periparturient rise, the second in October probably due to maturation of inhibited larvae. The worm burdens of tracer lambs showed that there was a gradual accumulation of nematodes from December, reaching a peak in May; an absence of infection in July and August during the dry period, and a second peak in November. Infection by Moniezia was higher during the dry season.