The effect of echinococcosis (hydatid disease) on carcase weight in cattle

Abstract Hydatid disease is caused by the zoonotic tapeworm Echinococcus granulosus. There has been ongoing controversy over whether it causes weight loss in cattle. Recently implemented recording of comorbidities at processors have provided opportunity to investigate this effect. Using prevalence-based observational data from 1,648,049 adult cattle processed in from seven states and territories in Australia (2019—2022), we explored associations between carcase weight, hydatid cysts, comorbidities, sex, age, and region. Linear mixed-effect regression models estimated the effect of hydatid disease on carcase weight, guided by directed acyclic graphs to reduce bias. The highest, previously unreported, prevalence was in the southeast Queensland region. The estimated effect of hydatid disease cysts on carcase weight ranged from 0.32kg (se 0.58kg; two-tooth 2022) to -5.45kg (se 0.63kg; six-tooth 2019) with most point estimates (11/16) between 0 – -2.5kg across all cattle grouped by year and dentition. This effect size would be practically undetectable in live cattle and is an important finding; cattle producers are unlikely to observe increased productivity through weight gain from hydatid disease prevention in cattle, and awareness to strengthen prevention in domestic dogs around cattle properties to reduce human risk remains a public health focus.