Widespread anthelmintic resistance in European farmed ruminants: a systematic review

Anthelmintic resistance (AR) in gastrointestinal nematodes (GINs) has been reported worldwide in multiple nematode and livestock species (Kaplan and Vidyashankar 2012) and is a major constraint on production on affected farms (Sutherland and others 2010, Miller and others 2012). In the UK and Ireland, for example, AR in GINs and anthelmintic treatment failure is widespread in sheep (e.g. Bartley and others 2003, Keane and others 2014) and increasingly reported in cattle (e.g. O’Shaughnessy and others 2014). There is, therefore, a need to develop and adopt GIN control strategies that maintain the efficacy of anthelmintics and to identify risk factors for the development of AR. A systematic review of peer-reviewed literature was undertaken to record the current distribution of AR in the major GINs (Teladorsagia species, Trichostrongylus species, Haemonchus contortus, Ostertagia ostertagi and Cooperia oncophora) infecting goats, sheep and cattle in Europe (defined as the EU, European Economic Area and Switzerland).