Re-infection with Fasciola gigantica 6-month post-treatment with triclabendazole in cattle from mobile pastoralist husbandry systems at Lake Chad

At Lake Chad in central Africa, livestock fascioliasis caused by Fasciola gigantica represents a major veterinary health problem, particularly in cattle reared in mobile pastoralist husbandry systems. We assessed re-infection after a single dose of triclabendazole with fascioliasis in cattle in a mobile pastoralist setting towards the end of the dry season. Within the cattle herds of 14 groups of mobile pastoralists, 375 cattle were randomly selected. A faecal sample was obtained from each animal to determine the prevalence of F. gigantica. Animals were administered a single oral dose of triclabendazole (12 mg/kg). A second faecal sample was obtained 6-month post-treatment after cattle had returned from the annual migration cycle. Faecal samples were fixed in sodium acetate-acetic acid-formalin (SAF), and examined for F. gigantica using the sedimentation technique. From the 375 cattle enrolled at baseline, 198 animals (53%) in 12 groups of mobile pastoralists were re-sampled at the 6-month follow-up. Baseline prevalence did not differ noteworthy between animals lost to follow-up and those re-examined. At baseline, bovine fascioliasis prevalence in cattle with follow-up data was 41.9% (95% confidence interval (CI) 35.2-48.9%). At the 6-month post-treatment follow-up, the prevalence was 46.0% (95% CI 39.2-52.9%), ranging between 0% and 75% at the herd level. The mean faecal egg counts at the unit of the herd were higher at follow-up compared to baseline. The observed persistent high prevalence of F. gigantica infection in cattle shows that a single pre-rainy season treatment does not prevent rapid re-infection despite the partial migration away from the high-risk areas at Lake Chad into drier areas. A locally adapted strategic control package for fascioliasis in cattle in the Lake Chad area ought to integrate targeted triclabendazole treatment and seasonal transhumance practices.