The contribution to the epidemiology of gastrointestinal nematodes of sheep with special focus on the survival of infective larvae in winter conditions

Abstract

Tracer tests conducted over a 3-year period were aimed at measuring the level and species nematode composition of survival on pastures with a special focus on winter months. The survival of infective larvae in chilly conditions is not significantly affected by Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus vitrinus and Chabertia ovina. On the contrary, the number of Teladorsagia circumcincta and Nematodirus filicollis significantly increased in milder winter conditions. The results confirmed an epidemiological strategy of overwintering in the arrested stage for Teladorsagia circumcincta and Nematodirus filicollis; the epidemiological strategy of genus Trichostrongylus used both strategies-in particular the tolerance of free-living stages to cold conditions. Part of the population overwintered in the arrested stage as well.

Influence of breed and parasite challenge on the immune response to naturally acquired intestinal nematode infection in sheep

“…Environmental conditions have great influence on the distribution of different nematode species and on the risk of massive infections (Wilmsen et al ., 2014; Almeida et al ., 2020). Unlike other countries where seasonality is observed in the epidemiology of intestinal parasites (De Chaneet & Dunsmore, 1988; Makovcová et al ., 2009; McMahon et al ., 2012), Brazil has favourable climatic conditions for the development and survival of nematode larvae in pastures throughout the year (Silva et al ., 2008; Rocha et al ., 2014; Almeida et al ., 2020). This fact contributes to high infection rates of animals, with cases of mortality, especially in young animals.…”