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Hydatidosis has become a real concern for health care institutions and animal rearers in Tunisia. The Tunisian endemicity is aggravated by the growing number of dogs and the difficulty of getting rid of contaminated viscera because of the lack of equipment in most slaughterhouses. Therefore, microscopic and molecular tools were applied to evaluate the role of slaughterhouses in canine infection and Echinococcus granulosus sensu lato (s. l.) egg dissemination. Exposure risk to E. granulosus s. l. eggs in urban and rural areas was explored in order to implant preventive and adapted control strategies. Microscopic examinations detected taeniid eggs in 152 amongst 553 fecal samples. The copro-PCR demonstrated that 138 of 152 taeniid samples analyzed were positive for E. granulosus s. l. DNA. PCR-RFLP demonstrated that all isolated samples belonged to E. granulosus sensu stricto (s. s.). An important environmental contamination index (25.0%) by E. granulosus s. l. eggs was demonstrated. The average contamination index from the regions around slaughterhouses (23.3%; 95% CI: 17.7-28.9%) was in the same range as detected in areas located far from slaughterhouses (26.0%, 95% CI: 21.3-30.8%). Echinococcosis endemic areas were extended in both rural (29.9%, 95% CI: 24.8-34.9%) and urban locations (18.1%, 95% CI: 13.0-22.9%). The pathogen dissemination is related neither to the presence/absence of slaughterhouses nor to the location in urban or rural areas, but is probably influenced by human activities (home slaughtering) and behavior towards the infected viscera.

Cystic echinococcosis (CE) or hydatidosis is a widespread zoonose in the world. In Tunisia, despite the deployed prevention program, CE remains a serious public health problem. With a human surgical annual incidence averaging 12.6/100000 inhabitants, Tunisia is one of the most endemic areas amongst the Mediterranean countries. Three Echinococcus species have been described: E. granulosus sensu stricto (G1 and G3 genotypes), E. canadensis, and E. equinus. CE, which commonly starts during childhood and described as a young adult disease, may be observed at any age. The liver and the lungs are the most commonly involved organs but the cyst can occur almost anywhere in the body. In production animals, the prevalence of CE is ranged from 16.42% to 40.42% in sheep, 8.56% in cattle, 6% in dromedaries, 2.9% in goats, and 8.48% in donkeys. The elevated number of stray and semi-stray dogs and their frequent contamination by E. granulosus infected viscera is the major cause of the CE spread. A high prevalence of E. granulosus infection has been reported in Tunisian dogs ranging from 3.75% to 27.1%, depending on the regions. Thus, the sanitary education concerning hydatidosis should be reinforced and efforts should be made to implement a targeted educational program.

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International audience; Ovine and dromedary Echinococcus granulosus isolates from Tunisia were identified as G1 and G6 strains based on polymorphism of the mitochondrial cytochrome C oxydase CO1. Single strand conformation polymorphism (SSCP) was used in order to examine the genetic variation within and between Tunisian G1 and G6 strains and to estimate the extent of selfing. The dromedary isolates are genetically distinct from sheep isolates (high value of genetic variation between populations: Fst = 0.46). No significant deficiency in heterozygotes was found in sheep isolates, whereas heterozygote deficiency (suggesting selfing) was found in a limited number of camel isolates.; Les Echinococcus granulosus de Tunisie ont été identifiés comme appartenant aux lignées G1 et G6 en se fondant sur le polymorphisme de la cytochrome oxydase CO1. Le polymorphisme de conformation simple brin (SSCP) a été utilisé afin d’évaluer la variabilité génétique intra et inter-isolats des lignées G1 et G6, et pour estimer le taux d’autofécondation. Les isolats issus de dromadaires sont génétiquement distincts des isolats ovins (valeur de Fst : 0,46). Il n’y a pas de déficit significatif en hétérozygotes chez les isolats ovins. Un déficit en hétérozygotes est présent dans les isolats du dromadaire, ce qui suggère l’autofécondation comme l’un des modes de reproduction.

Background Tunisia is a hyper endemic country for human echinococcosis. The infection is transmitted via the eggs of Echinococcus granulosus which are passed in the faeces of the definitive canid host. Methods This study evaluated the contamination rate of the dog faeces in different climatic conditions at eight different geographic regions throughout Tunisia. Dog faecal samples were collected from the soil and the Echinococcus eggs were identified using microscopic and molecular (Eg1121/1122 PCR, Egss1 PCR and Nad1 PCR-RFLP) tools. Results The contamination index of dog faeces by E. granulosus eggs ranged from 8.3% to 41.3% depending on the region. Comparisons of the dog faecal contamination rate against human incidence found them to be independent. Neither human prevalence nor dog contamination index appeared to be related to climatic conditions or geographic characteristics. The genetic variability of E. granulosus samples was different within each region but was not related to geographic distance which is indicative of local divergent evolutions rather than isolation by distance. Conclusions A high environmental dog contamination index does not necessarily correspond to high prevalence in humans as transmission is strongly linked to human behavior and hygiene.