Canine echinococcosis, caused by the adult form of taeniid cestodes of the genus Echinococcus is zoonotic and has an epidemiologically worldwide distribution. Dogs infected with E. granulosus are the main source of human hydatidosis, however, there is little information on molecular epidemiology of adult Echinococcus spp. in stray dogs. In the present study, 100 stray dogs (48 males and 52 females, 72 adults and 28 juveniles) were collected from Khorasan Razavi province in Northeastern Iran during October 2013 to December 2014. Thirty-eight (21 males and 17 females, 3 juveniles and 35 adults) out of 100 dogs were infected with E. granulosus. There were no significant differences in prevalence observed between females (43.5%) and males (34.4%), however, the prevalence of E. granulosus, showed a significant increasing trend with increasing host age (p < 0.05). Thirty-eight isolated parasites from 38 stray dogs (one parasite per dog) were used for PCR-RFLP analysis of the ITS1 gene. PCR-RFLP analysis showed that all the 38 parasites were E. granulosus G1 genotype (common sheep strain). Five PCR products were sent for sequencing. The results of sequencing were similar to those reported by PCR-RFLP analysis and the presence of E. granulosus G1 genotype (sheep strain) as dominant genotype in dogs were emphasized. The results of this study suggest that the sheep strain occurs in definitive host in Northeastern Iran. Data presented here are expected to be useful for health and educational authorities responsible for designing and implementing effective measures for disease control.

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