Abstract. We evaluated the genetic variation of Echinococcus G7 strain in larval and adult stages using a fragment of the mitochondrial cox1 gen. Viscera of pigs, bovines, and sheep and fecal samples of dogs were inspected for cystic and canine echinococcosis, respectively; only pigs had hydatid cysts. Bayesian inferences grouped the sequences in an E. canadensis G7 cluster, suggesting that, in Mexico, this strain might be mainly present. Additionally, the population genetic and network analysis showed that E. canadensis in Mexico is very diverse and has probably been introduced several times from different sources. Finally, a scarce genetic differentiation between G6 (camel strain) and G7 (pig strain) populations was identified.Echinococcus granulosus sensu lato (s.l.) includes species that cause cystic echinococcosis (CE), one of the most important and widespread parasitic zoonoses. Recent phylogenetic studies based on both mitochondrial and nuclear DNA genes show that E. granulosus s.l. consists of at least four valid species: E. granulosus sensu stricto (s.s.; genotypes G1-G3), E. equinus (G4), E. ortleppi (G5), and E. canadensis (G6-G10). Genotypes G6/G7 are closely related and referred to as camel and pig strains, respectively.

No epidemiologic study for cystic echinococcosis in México has yet been described. The objective of this work was to determine the prevalence and distribution of human echinococcosis in a community of the state of México and its probable risk factors. A cross-sectional study was performed; household census was used to randomly select houses. The larval stage of Echinococcus was searched by ultrasound in liver, spleen, and kidney. A questionnaire was used for the investigation of risk factors. The study was performed with 401 persons, 64% were female. The prevalence of echinococcosis was 0.75%. Cases were distributed in the same sector of the community. The close distribution of cases suggests the same exposure source. There were 426 dogs in the community; feces were collected from 414 of these in search of cestode eggs. After treatment, 3 dogs had Taenia pisiformis but none had Echinococcus. This paper pioneers the search of human echinococcosis in México because it provides evidence of the presence of this tissue parasite at the community level.