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BackgroundTunisia 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.MethodsThis 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.ResultsThe 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.ConclusionsA high environmental dog contamination index does not necessarily correspond to high prevalence in humans as transmission is strongly linked to human behavior and hygiene.

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Cystic echinococcosis, due to Echinococcus granulosus sensu lato (s. l.), currently affects three million people, especially in low-income countries and results in high livestock production loss. DNA-based methods demonstrated genetic variability of E. granulosus s. l., and five species were recognized to belong to the complex, including E. granulosus sensu stricto (s.s) (genotypes G1-G3), Echinococcus equinus (genotype G4), Echinococcus ortleppi (genotype G5), Echinococcus canadensis (genotypes G6-G10), and the lion strain Echinococcus felidis. The characterization of Echinococcus species responsible for human and animal echinococcosis is crucial to adapt the preventive measures against this parasitic disease. The sequencing approach is the gold standard for genotyping assays. Unfortunately, developing countries do not often have access to these techniques. Based on in silico RFLP tools, we described an accurate PCR-RFLP method for Echinococcus spp. characterization. The double digestion with the HaeIII and HinfI restriction enzymes of the PCR product from nad1 gene (1071 bp) led to a clear discrimination between E. granulosus s. l. and most closely related species (Echinococcus shiquicus and Echinococcus multilocularis).Molecular procedures and phylogenetic analysis confirmed the efficiency and the reproducibility of this simple and fast PCR-RFLP method. This technique is proved useful for fresh/unfixed and FF-PET tissues and enables large-scale molecular epidemiological screening in developing countries.