Evaluation of Helminth Infections Identified in Slaughtered Livestock in Iran, 2015-2019

Introduction: Helminth infections of livestock can result in considerable economic losses. This study aims to evaluate the spatial frequency of cystic echinococcosis (CE), dicrocoeliasis, and fascioliasis in livestock slaughtered in Iran during the years 2015-2019 and estimate direct costs associated with organ condemnation due to these parasites.Methods: Abattoir data from all 31 Iranian provinces were collected from the Iran Veterinary Organization. Infection prevalence was calculated per year at the province level. The Local Moran's I statistic was performed to evaluate spatial autocorrelation of animals positive at slaughter for the years 2015-2019. Direct costs associated with condemned livers were calculated for each parasitic condition. Results: Overall prevalence values for the study timeframe were as follows: sheep and goat fascioliasis (1.5%, 910,282/58,393,349), cattle fascioliasis (3.8%, 23,3175/6,038,419), sheep and goat dicrocoeliasis (4.6%; 270,1274/58,393,349), cattle dicrocoeliasis (3.1%; 186,009/6,038,419), sheep and goat CE (5.3%; 3,108,767/58,393,349), and cattle CE (7.2%; 438,534/6,038,419). Northwestern Iran had the highest prevalence of CE and fascioliasis. High infection areas for Dicrocoelium spp. included the provinces of Zanjan, Gilan, Qazvin, and Tehran, which are located in northern Iran. Direct economic losses for sheep and goat fascioliasis, dicrocoeliasis, and CE for the study period were US$13,841,826, US$41,768,472, and US$22,801,296, respectively. Direct economic losses for cattle fascioliasis, dicrocoeliasis, and CE for the study period were US$1,989,582, US$1,669,289, and US$2,656,535, respectively.Conclusion: Our findings provide valuable data for future monitoring of these important parasitic diseases in Iranian livestock. Disease control strategies are required to reduce the economic and public health impact of these helminths.