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Abdou Malik Da Silva thesis defense

Abdou Malik Da Silva will defend his Science thesis at 9 am on Thursday 16 December, in the Bio-Innovation building next to the Besançon University Hospital (4 rue Charles Bried, 25000 Besançon) on the Hauts-du-Chazal site.
His topic is the study of the role of definitive hosts involved in environmental contamination by Echinococcus multilocularis in endemic areas.

As the number of people present is limited, the defense will be broadcasted by video. To obtain the link, do not hesitate to register by e-mail at abdou_malik.da_silva at univ-fcomte.fr

Composition of the jury
Raoul Francis, University Professor, University of Burgundy Franche-Comté Examiner
Gottstein Bruno, Professor, University of Bern Rapporteur
Berry Antoine, PU-PH, University of Toulouse III Rapporteur
Hayette Marie-Pierre, Professor, University of Liège Examiner
Umhang Gérald, Research Officer, ANSES/LRFS/LNR Echinococcus spp.
Bart Jean-Mathieu, Research Officer, IRD/UMR INTERTRYP Examiner
Millon Laurence, PU-PH, University of Bourgogne Franche-Comté Thesis Director
Knapp Jenny, Research Fellow, University of Burgundy Franche-Comté Co-director of the thesis

Abstract

Alveolar echinococcosis remains an expanding zoonosis despite improved sanitary measures, changing dietary habits and decreasing populations in the most at-risk socio-economic categories. Environmental contamination by Echinococcus multilocularis, the parasite responsible for this zoonosis, and the risk of infection for humans depend on the distribution of faeces of carnivore final hosts of the parasite. This study aimed to characterise the contribution of foxes, dogs and cats to environmental contamination by E. multilocularis in endemic areas. The presence of E. multilocularis eggs was confirmed more significantly in fox faeces. Furthermore, our work demonstrated local spatial heterogeneity in the risk of exposure to E. multilocularis eggs via fox faeces, which represents a key parameter in the local transmission of the parasite. In addition, the study of E. multilocularis contamination of kitchen garden soils suggests that parasite eggs could persist for at least a year after the parasite-bearing faeces have disappeared. The contribution of individual foxes to environmental contamination by E. multilocularis was explored by identifying their faeces by genotyping with microsatellite markers. Among the infested foxes, we identified a few individuals (35%) that deposited the majority of faeces that tested positive for E. multilocularis (60%). Finally, the identification of the EmsB genetic profiles of E. multilocularis eggs isolated from the faeces of the hosts suggests a transmission of the parasite from foxes, then considered as a local reservoir of the parasite, to dogs and cats via predation of the same local rodent population. The work as a whole demonstrates the major role of the sylvatic cycle maintained by foxes in maintaining the synanthropic cycle of the parasite. It seems then that measures to control the abundance of E. multilocularis in the field must necessarily cover the territory of the foxes that are super-propagators of the parasite in order to hope to interrupt the local cycle of the parasite.

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