First phylogenetic perspective on molecular epidemiology of Echinococcus granulosus sensu lato in dogs in Sistan and Baluchestan Province, southeastern border region of Iran

Background: Hydatidosis is a neglected cyclo-zoonotic disease in Middle East countries particularly southeast of Iran which is caused by metacestode of tapeworm Echinococcus granulosus sensu lato. Human hydatidosis is a high public health priority in the area, however there is little known from a phylogenetic perspective on molecular epidemiology of adult Echinococcus spp. in Iranian shepherd dogs. Materials and Methods: 50 shepherd dogs were investigated for adult worm of E. granulosus from May 2020 to April 2021 in Sistan and Baluchestan Province, southeastern border region of Iran. DNA samples were extracted, amplified, and subjected to sequence analysis of mitochondrial genes (cox1 and nad1). Results: Out of 50 shepherd dogs, 11 (22%) cases were infected with genus E. granulosus. Regarding demographic factors, the frequency of parasitism in both male, female adults and their age groups showed no difference (P > 0.05). The phylogenetic analyses of cox1 and nad1 sequences firmly revealed sheep strains (G1) in all isolates. Based on sequence analyses, a low (cox1, Hd: 0.200; Hn: 2) to moderate (nad1, Hd: 0.533; Hn: 4) genetic (haplotype) diversity of E. granulosus G1 genotype and a low nucleotide diversity (π: 0.00052-0.00243) were observed. Conclusion: first presence of sheep strain (G1) in the final host of this region seems to indicate that potential intermediate hosts play a secondary role in the maintenance of sheep-dog biology. Current findings have heightened our knowledge about determination of E. granulosus prevalence, strains of taxonomy and genotypic trait of parasite in Iranian shepherd dogs which will also help in the development of strategies for monitoring and control of infected stray dogs in the area.