Dynamics of the elimination of Dicrocoelium dendriticum (Trematoda, Digenea) eggs in the faeces of lambs and ewes in the Porma basin (León, NW Spain).

The elimination of Dicrocoelium dendriticum eggs in sheep faeces from 4 localities in the upper and middle Porma river basin was recorded at monthly intervals between March 1986 and March 1987. The faecal material was taken directly from the rectum of the animals (10% of the flock in each village). The sedimentation technique and McMaster egg counting chambers were used to analyze the faecal samples. Of the 995 samples examined, 63.6% contained D. dendriticum eggs and the number of eggs per gram (epg) varied from 33 to 5,340 (average 323.4 +/- 18.5). The highest elimination rate was observed in winter, not only because of prevalence (90.5%) but also because of the epg (average 726.6 +/- 88.4). Prevalence of infection (from 61.5 to 65.4%) was similar for all age groups, although the highest mean epg value (367.6 +/- 50.9) was found in lambs.