Mini-FLOTAC as an alternative, non-invasive diagnostic tool for Schistosoma mansoni and other trematode infections in wildlife reservoirs

Stefano Catalano,Nicolas D Diouf,Joanne P Webster,Mariama Sène,Kirsty J Marsh,Amelia Symeou,Cheikh B Fall,Davide Ianniello,Elsa Léger,Laura Rinaldi,Giuseppe Cringoli,Khalilou Bâ,Anna Borlase

doi:10.1186/s13071-019-3613-6

Abstract

BackgroundSchistosomiasis and food-borne trematodiases are not only of major public health concern, but can also have profound implications for livestock production and wildlife conservation. The zoonotic, multi-host nature of many digenean trematodes is a significant challenge for disease control programmes in endemic areas. However, our understanding of the epidemiological role that animal reservoirs, particularly wild hosts, may play in the transmission of zoonotic trematodiases suffers a dearth of information, with few, if any, standardised, reliable diagnostic tests available. We combined qualitative and quantitative data derived from post-mortem examinations, coprological analyses using the Mini-FLOTAC technique, and molecular tools to assess parasite community composition and the validity of non-invasive methods to detect trematode infections in 89 wild Hubert’s multimammate mice (Mastomys huberti) from northern Senegal.ResultsParasites isolated at post-mortem examination were identified as Plagiorchis sp., Anchitrema sp., Echinostoma caproni, Schistosoma mansoni, and a hybrid between Schistosoma haematobium and Schistosoma bovis. The reports of E. caproni and Anchitrema sp. represent the first molecularly confirmed identifications for these trematodes in definitive hosts of sub-Saharan Africa. Comparison of prevalence estimates derived from parasitological analysis at post-mortem examination and Mini-FLOTAC analysis showed non-significant differences indicating comparable results between the two techniques (P = 1.00 for S. mansoni; P = 0.85 for E. caproni; P = 0.83 for Plagiorchis sp.). A Bayesian model, applied to estimate the sensitivities of the two tests for the diagnosis of Schistosoma infections, indicated similar median posterior probabilities of 83.1% for Mini-FLOTAC technique and 82.9% for post-mortem examination (95% Bayesian credible intervals of 64.0–94.6% and 63.7–94.7%, respectively).ConclusionsOur results showed that the Mini-FLOTAC could be applied as an alternative diagnostic technique for the detection of the zoonotic S. mansoni and other trematodes in rodent reservoirs. The implementation of non-invasive diagnostics in wildlife would offer numerous advantages over lethal sampling methodologies, with potential impact on control strategies of zoonotic helminthiases in endemic areas of sub-Saharan Africa and on fostering a framework of animal use reduction in scientific practice.

Highlights

Schistosomiasis and food-borne trematodiases are of major public health concern, but can have profound implications for livestock production and wildlife conservation
Based on the combined morphological and molecular analysis of ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA) data, the trematodes collected at post-mortem were identified as Echinostoma caproni, Plagiorchis sp., Anchitrema sp., S. mansoni, and a hybrid between Schistosoma haematobium and Schistosoma bovis
The Mini-FLOTAC analysis identified parasitic eggs in 85 out of 89 individuals (95.5%; 95% Confidence intervals (CI): 88.7–98.6%), which were morphologically compatible with: Plagiorchis sp. in 76 hosts (85.4%; 95% CI: 76.5–91.4%); S. mansoni in 21 hosts (23.6%; 95% CI: 15.9–33.5%); Echinostoma sp. in 18 hosts (20.2%; 95% CI: 13.1–29.8%); and Anchitrema sp. in one host (1.1%; 95% CI: 0–0.7%) (Fig. 1)

Summary

Introduction

Schistosomiasis and food-borne trematodiases are of major public health concern, but can have profound implications for livestock production and wildlife conservation. The zoonotic, multi-host nature of many digenean trematodes is a significant challenge for disease control programmes in endemic areas. The complex multi-host, zoonotic nature of trematodiases may have a considerable impact on the outcome of disease control programmes in endemic areas [9, 10]. The role of wild small mammals as disease reservoirs is emerging as a public health concern, and the involvement of rodents in the transmission of human agents of schistosomiasis (e.g. Schistosoma japonicum and Schistosoma mansoni) in different regions of the world is a noteworthy example [11,12,13]. The exclusive application of molecular techniques may under represent parasite community composition and inaccurately depict quantitative estimates of infection if inferences are not properly tested [9, 14]

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