Epidemiology of parasitosis in the Tzotzil sheep production system J. Nahed-Toral a,∗ , Q. López-Tirado b , G. Mendoza-Mart´ õnez c , A. Aluja-Schunemann d , F.J. Trigo-Tavera e

The prevalence of parasitic infections in sheep caused by Eimeria spp., intestinal nematodes, Dictyocaulus filaria and Fasciola hepaticawas analyzed. The study was carried out in 78 crossbred adult sheep, from 15 different flocks (10 .5 ± 6.5 sheep), which belonged to five different indigenous Tzotzil communities in the highlands of Chiapas, Mexico. Feces were collected for parasitologic analysis during the four seasons of the year. The results indicated a high average prevalence of Eimeria sp. (81.7%) and intestinal nematodes (76.9%), with a higher presence of subclinical infection, and a lower proportion of moderate and severe infection during summer and winter. The occurrence of Fasciola hepatica(37.5%) and Dictyocaulus filaria (16.7%) was also concentrated at summer and winter. Geographically, the highest prevalence of Eimeria spp. was found at Bautista Chico (90.0%) and Luquilho (83.0%); of intestinal nematodes at Mitziton (90.0%) and Nachig (87.0%). Fasciola hepatica highest prevalence was at Nachig (50.0%) and Mitziton (50.0%); and Dictyocaulus filaria at Mitziton (35.0%) and Nachig (25.0%). The occurrence of ectoparasites was also investigated. The seasonal fluctuation of parasitic infections was correlated (r ≥ 0.60) with climatic changes, forage availability, dry matter intake and body weight. The environmental factors, when associated with poor management of the flocks, reduced the tolerance of sheep to the different parasitoses.