Molecular Confirmation of a Fasciola gigantica × Fasciola hepatica Hybrid in a Chadian Bovine.

Fascioliasis is a zoonotic infection of humans and, more commonly, ruminants. It is caused by 2 liver fluke species, Fasciola hepatica and Fasciola gigantica, which differ in size. The traditional morphological methods used to distinguish the 2 species can be unreliable, particularly in the presence of hybrids between the 2 species. The development of advanced molecular methods has allowed for more definitive identification of Fasciola species, including their hybrids. Hybrids are of concern, as it is thought that they could acquire advantageous traits such as increased pathogenicity and host range. In 2013, we collected flukes from Fasciola-positive cattle, sheep, and goats slaughtered in 4 Chadian abattoirs. DNA from 27 flukes was extracted, amplified, and analyzed to identify species using the ITS1+2 locus. Twenty-six of the 27 flukes were identified as F. gigantica, while the remaining fluke showed heterozygosity at all variable sites that distinguish F. hepatica and F. gigantica. Cloning and sequencing of both alleles confirmed the presence of 1 F. hepatica and 1 F. gigantica allele. To our knowledge, this is the first unambiguous, molecular demonstration of the presence of such a hybrid in a bovine in sub-Saharan Africa.

Human and livestock trematode infections in a mobile pastoralist setting at Lake Chad: added value of a One Health approach beyond zoonotic diseases research.

Background: At Lake Chad in Central Africa, mobile pastoralists face economic losses due to livestock trematodiases. Fasciola gigantica and Schistosoma bovis-trematodes that affect livestock-share transmission ecology traits with Schistosoma haematobium and S. mansoni that cause human schistosomiasis. This project aimed at assessing treatment strategies and elucidating the predictive potential of human and livestock trematode infections. Methods: Schistosomiasis and fascioliasis were investigated concurrently in humans and cattle by repeated cross-sectional surveys. Urine and stool samples from humans and faecal samples from cattle were examined for trematode eggs. Treatment strategies were assessed by means of focus group discussions and in-depth interviews. Results: Mobile pastoralists of four ethnic groups participated. Prevalence of human schistosomiasis and livestock trematodiases showed considerable heterogeneity from one ethnic group to another, but correlated within ethnic groups. Effective trematocidal drugs were not available in the study area. Conclusions: Mutual predictive potential of human schistosomiasis and livestock fascioliasis relates to distinct livestock husbandry practices. Introducing efficacious strategic treatment against human schistosomiasis and livestock fascioliasis might improve human and animal health and well-being. Our research provides evidence for the benefits of a One Health approach targeting diseases that share specific ecological traits.

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 (12mg/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.