Inquérito parasitológico em humanos e caracterização genética de Echinococcus vogeli em pacas (Cuniculus paca) de reservas florestais do Acre. Brasil

Abstract

In the Amazon Rainforest, it is common to hunt wild animals as a food resource. The forest dwellers live far from urban centers with a lack of access to education, health services, basic sanitation, and clean water, increasing zoonoses and intestinal parasites. There are few approaches involving collection, molecular characterization, analysis, and data survey about the population genetics of species that cause neotropical echinococcosis (Echinococcus vogeli and Echinococcus oligarthra), especially obtained from lowland pacas in the Brazilian Amazon Rainforest. The genetic variability of E. granulosus sensu lato has already been proven and the knowledge of the E. vogeli genetics can contribute to the control, prevention, and diagnosis programs for polycystic neotropical echinococcosis (PNE). A specific local habit is the ingestion of these animals’ livers undercooked, contributing to the transmission of Calodium hepaticum, the etiologic agent of hepatic capillariasis. The ingestion of unembryonated eggs of this helminth causes the spurious infection, characterized by the passing of these eggs through the intestinal tract and then the release with the feces, all this without causing liver disease. However, humans in this condition act as dispersers of the eggs in the environment, which may contribute to the other hosts’ infection. The objectives of this work were the molecular characterization (PCR and sequencing) of lowland pacas’ E. vogeli isolates from the state of Acre and the parasitological survey (spontaneous sedimentation, centrifugal-sedimentation, and Kato-Katz) and sociodemographic (questionnaire application) of the forest reserves dwellers from two municipalities of Acre, Brazil: Xapuri and Sena Madureira. The collect locations were based on reports of human cases of PNE, according to the data of the National Reference Laboratory on Hydatidosis at IOC/Fiocruz-RJ (LRNH-LHPV-IOC/Fiocruz). All the 13 E. vogeli isolates (cysts extracted from livers) were PCR positive for the cox1 and P-29. For the cox1 gene, our samples showed genetic similarity with all E. vogeli sequences available in GenBank-NCBI related to the Brazilian Amazon Rainforest, especially with those from Acre itself. Our analysis revealed three segregation sites and four haplotypes, one central and two shared between the two study locations. There was no genetic diversity for E. vogeli in the P-29 sequences obtained. In the 276 stool samples examined, hookworm eggs (19.2%), C. hepaticum eggs (1.1%) and Blastocystis sp. (6.9%). It is concluded that: This is the third study on the structure and genetic variability of E. vogeli populations, being one of the few to work with the nuclear gene P-29. Concerning the neglected context of PNE, all efforts that seek to elucidate the diversity and genetic structure of E. vogeli will contribute to studies regarding taxonomic, evolutionary, diagnosis, epidemiology, disease prevention and control. The habit of eating raw paca meat is a risk factor for spurious C. hepaticum infection in Sena Madureira and Xapuri. The study represents the first report of Blastocystis sp. in Acre. Infection by geohelminths and intestinal protozoa is related to the precarious sanitary conditions of the inhabitants of the study area.