Human cystic echinococcosis caused by the larval stage of Echinococcus granulosus sensu lato (s.l.) is a highly endemic disease in the province of Neuquén, Patagonia, Argentina. Human infections with E. granulosus sensu stricto (s.s.) G1 and Echinococcus canadensis G6 were reported in Neuquén in previous studies, whereas four genotypes were identified in livestock: G1, G3, G6, and G7. The aim of this study was to identify the genotypes of E. granulosus s.l. isolates from humans of Neuquén province, Patagonia, Argentina, through the 2005-2014 period. Twenty six hydatid cysts were obtained from 21 patients. The most frequent locations were the liver and lungs. Single cysts were observed in 81.0% of patients, and combined infection of liver and lungs was detected in 9.5% of cases. Partial sequencing of mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes identified the presence of E. granulosus s.s. G1 (n = 11; 42.3%) including three different partial sequences; E. canadensis G6 (n = 14; 53.8%) and E. canadensis G7 (n = 1; 3.9%). Coinfection with G1 and G7 genotypes was detected in one patient who harbored three liver cysts. Most of the liver cysts corresponded to G1 and G6 genotypes. This study presents the first report in the Americas of a human infection with E. canadensis G7 and the second worldwide report of a coinfection with two different species and genotypes of E. granulosus s.l in humans. The molecular diversity of this parasite should be considered to redesign or improve the control program strategies in endemic regions.

Cystic echinococcosis caused by Echinococcus granulosus sensu lato is one of the most important helminth zoonoses in the world; it affects both humans and livestock. The disease is endemic in Argentina and highly endemic in the province of Neuquén. Considerable genetic and phenotypic variation has been demonstrated in E. granulosus, and ten different genotypes (G1-G10) have been identified using molecular tools. Echinococcus granulosus sensu lato may be considered a species complex, comprised of E. granulosus sensu stricto (G1-G3), E. equinus (G4), E. ortleppi (G5) and E. canadensis (G6-G10). In endemic areas, the characterization of cystic echinococcosis molecular epidemiology is important in order to apply adequate control strategies. A cut-off value for larval large hook total length to distinguish E. granulosus sensu stricto isolates from those produced by other species of the complex was defined for the first time. Overall, 1780 larval hooks of 36 isolates obtained from sheep (n= 11, G1), goats (n= 10, G6), cattle (n= 5, G6) and pigs (n= 10, G7) were analysed. Validation against molecular genotyping as gold standard was carried out using the receiver operating characteristic (ROC) curve analysis. The optimum cut-off value was defined as 26.5 μm. The proposed method showed high sensitivity (97.8%) and specificity (91.1%). Since in most endemic regions the molecular epidemiology of echinococcosis includes the coexistence of the widely distributed E. granulosus sensu stricto G1 strain and other species of the complex, this technique could be useful as a quick and economical tool for epidemiological and surveillance field studies, when fertile cysts are present.

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Most human cystic echinococcosis (CE) cases worldwide are attributed to Echinococcus granulosus sensu stricto (s.s), followed by the G6 and G7 genotypes. While E. granulosus s.s. has a cosmopolitan distribution, the G6 genotype is restricted to areas where camels and goats are present. Goats are the primary livestock in the Neuquén province in Argentina where the G6 genotype has been reported to be responsible for a significant percentage of CE human cysts genotyped. In the present study, we genotyped 124 Echinococcus cysts infecting 90 CEconfirmed patients. Echinococcus granulosus s.s. was identified in 51 patients (56.7%) with 81 cysts and the G6 genotype in 39 patients (43.3%) harbouring 43 cysts. Most CE cases ≤ 18 years were male suggesting pastoral work could be a risk factor for the infection. Echinococcus granulosus s.s. was significantly found more frequently in the liver (32/51 patients) and the G6 genotype in the lungs and extrahepatic localisations (27/39). The patients infected with E.