Initial assessment of the economic burden of major parasitic helminth infections to the ruminant livestock industry in Europe

•Initial framework to estimate economic burden of helminths to the ruminant livestock industry developed.•Annual cost of livestock infections with helminths in 18 countries estimated at €1.8 billion.•The cost of anthelmintic resistant nematodes estimated at € 38 million annually.•Data gaps to improve estimations in the future identified. We report a European wide assessment of the economic burden of gastrointestinal nematodes, Fasciola hepatica (common liver fluke) and Dictyocaulus viviparus (bovine lungworm) infections to the ruminant livestock industry. The economic impact of these parasitic helminth infections was estimated by a deterministic spreadsheet model as a function of the proportion of the ruminant population exposed to grazing, the infection frequency and intensity, the effect of the infection on animal productivity and mortality and anthelmintic treatment costs. In addition, we estimated the costs of anthelmintic resistant nematode infections and collected information on public research budgets addressing helminth infections in ruminant livestock. The epidemiologic and economic input data were collected from international databases and via expert opinion of the Working Group members of the European Co-operation in Science and Technology (COST) action COMbatting Anthelmintic Resistance in ruminants (COMBAR). In order to reflect the effects of uncertainty in the input data, low and high cost estimates were obtained by varying uncertain input data arbitrarily in both directions by 20 %. The combined annual cost [low estimate-high estimate] of the three helminth infections in 18 participating countries was estimated at € 1.8 billion [€ 1.0–2.7 billion]. Eighty-one percent of this cost was due to lost production and 19 % was attributed to treatment costs. The cost of gastrointestinal nematode infections with resistance against macrocyclic lactones was estimated to be € 38 million [€ 11–87 million] annually. The annual estimated costs of helminth infections per sector were € 941 million [€ 488 – 1442 million] in dairy cattle, € 423 million [€ 205–663 million] in beef cattle, € 151million [€ 90–213 million] in dairy sheep, € 206 million [€ 132–248 million] in meat sheep and € 86 million [€ 67–107 million] in dairy goats. Important data gaps were present in all phases of the calculations which lead to large uncertainties around the estimates. Accessibility of more granular animal population datasets at EU level, deeper knowledge of the effects of inf