Development of a milk and serum ELISA test for the detection of Teladorsagia circumcincta antibodies in goats using experimentally and naturally infected animals.

Teladorsagia circumcincta is among the most important gastrointestinal parasites in small ruminants and the predominant species in Southern European goats. Parasite control is largely based on metaphylactic/preventative treatments, which is often seen as non-sustainable anymore. The reasons are increased consumer demand to reduce chemicals in livestock production and anthelmintic resistance against the common drugs. This study aimed at the development of a T. circumcincta-enzyme-linked immunosorbent assay (ELISA) specifically for goats. Samples were obtained from goats raised parasite-free or infected experimentally. Sampling continued during the following pasture season and housing period. The sensitivity for the use in bulk milk samples as an indicator of T. circumcincta infection levels in grazing goats was examined. The ELISA enables clear differentiation of negative and positive animals. With a specificity of 100% negative cut-off values for serum and milk were 0.294 and 0.228 (sensitivity, 95%). Positive cut-off values (sensitivity, 90%) were 0.606 (serum) and 0.419 (milk), while a sensitivity of 95% resulted in 0.509 and 0.363, respectively. The grey-zone between negative/positive cut-offs was introduced to deal with animals in pre-patency and decreasing antibody levels after infection. There was no cross reactivity for Trichostrongylus colubriformis and Cooperia oncophora while for Haemonchus contortus and Fasciola hepatica it cannot be fully excluded currently. In bulk milk samples, 5% of the milk had to be contributed from animals infected with T. circumcincta to be detected as positive. The results derived from experimentally and naturally infected as well as parasite naïve animals indicate the potential of the ELISA to be used in targeted anthelmintic treatment regimes in goats.