Human cystic echinococcosis: first molecular identification of Echinococcus canadensis G7 in Brazil.

Echinococcus granulosus sensu lato (s.l.) is a species complex with the potential to cause cystic echinococcosis (CE). Contact with the feces of domestic dogs (Canis familiaris) fed with raw viscera of intermediate livestock hosts is a risk factor for this infection in the southern region of Brazil. Although the region has been considered endemic to CE for many years, molecular data regarding the species of the complex causing CE in humans are scarce. This study aimed to perform a molecular analysis of the biological fluid from a human liver cyst to investigate the species responsible for CE. Genetic material obtained from the hydatid fluid of a hepatic cyst from a human with CE was subjected to PCR to amplify mitochondrial and nuclear DNA sequences. The phylogenetic analysis confirmed the human infection by Echinococcus canadensis G7 in the state of Paraná, Brazil. This is the first molecular record of E. canadensis G7 infecting a human in Brazil, and it is important to reiterate the risk of human CE caused by this species in South America, as reported by a previous study in Patagonia, Argentina. From the epidemiological point of view, this finding is of great relevance for the southern region of Brazil, since this parasite has previously only been detected in pigs in the state of Rio Grande do Sul, neighboring Paraná. The finding points to the importance of this identification in the molecular epidemiology of E. granulosus s.l., especially in South America.

Diversity of helminths with zoonotic potential and molecular characterization of Toxocara canis infecting domestic dogs from locations of Amazon and Atlantic Forest Brazilian biomes.

The coproparasitological examination of dogs (n=278) from two Brazilian biomes (Amazon [AZ] and Atlantic Forest [AF]) by centrifugal flotation demonstrated positivity values of 54.2% (AF) and 48.5% (AZ). The most prevalent parasites in AF were hookworms (81.0% - 47/58), Toxocara sp. (17.3% - 10/58) and Trichuris vulpis (12.1% - 7/58); while in AZ they were hookworms (86.7% - 72/83), Toxocara sp. (18.1% - 15/83), Dipylidium caninum (13.3% - 11/83) and T. vulpis (10.8% - 9/83). PCR was performed using the partial mitochondrial genes cytochrome c oxidase subunit 1 (pcox1) and NADH dehydrogenase 1 (pnad1) in 25 fecal samples positive for Toxocara sp. eggs and found one sample positive for pcox1 and six positives for pnad1. The sequencing of these samples was unsuccessful due to the difficulties inherent in copro-PCR+sequencing. The sequencing of 14 samples of T. canis adult helminths retrieved 11 sequences of 414 bp for pcox1 and nine sequences of 358 bp for pnad1. The phylogenetic trees of these sequences confirmed the species T. canis. Intraspecific genetic variation was only observed for pnad1. This is the second study involving molecular analysis of T. canis in dogs from Brazil and adds new information through the use of pnad1.