Background Echinococcus granulosus (sensu lato) (s.l.) and Echinococcus vogeli are causative agents of chronic zoonotic diseases such as cystic and polycystic echinococcosis, respectively. In Brazil, polycystic echinococcosis has a restricted geographical distribution in the North Region, while cystic echinococcosis is observed in the South Region. Domestic dogs (Canis familiaris) fed with raw viscera represent a risk factor for E. granulosus (s.l.) infection in the South Region. Although this practice is frequent, it remains unclear whether domestic dogs are infected with E. vogeli in the state of Acre, located in the Amazon basin in the North Region of Brazil. The aim of this study was to investigate this gap in the polycystic echinococcosis epidemiology.MethodsSixty-five fecal samples were collected from the ground in five municipalities (Sena Madureira, n = 14; Rio Branco, n = 06; Bujari, n = 06; Xapuri, n = 30; and Epitaciolândia, n = 09) located in the state of Acre, northern Brazil. The samples were screened for parasites by copro-PCR using the cox1 gene associated with automated sequencing.Results Echinococcus vogeli was molecularly confirmed in a sample from Sena Madureira and E. granulosus (sensu stricto) (s.s.) (G1) in a sample from Rio Branco.ConclusionsThese findings indicate that molecular assays are useful in typing Echinococcus taxa from fecal samples of dogs in northern Brazil. The present study is the first molecular record of E. vogeli in domestic dogs found in the state of Acre, reinforcing their role as a source of infection for humans. Because E. granulosus (s.s.) (G1) was detected for the first time in the North Region, from the epidemiological standpoint this finding is highly relevant, because it expands the known geographical distribution, which was previously restricted to the South Region of Brazil.

Human polycystic echinococcosis is a parasitic infection caused by the larval stage of Echinococcus vogeli, which occurs in rural areas of Central and South America. Until now, little information on the genetic variability of E. vogeli is available. Here, 32 samples from human-excised E. vogeli cysts had a 396-bp sequence of the mitochondrial cytochrome oxidase I (COI) gene sequenced and compared to another 17 COI sequences representing nine Echinococcus species. A Bayesian COI tree revealed that all E. vogeli sequences formed a monophyletic and well-supported clade with an E. vogeli reference sequence. The occurrence of geographically restricted E. vogeli COI haplotypes suggests retention of ancestral polymorphisms with little migration in Acre, Brazil.

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Polycystic echinococcosis, caused by the larval stage (metacestode) of the small-sized tapeworm, Echinococcus vogeli, is an emerging parasitic zoonosis of great public health concern in the humid tropical rainforests of South and Central America. Because morphological and morphometric characteristics of the metacestode are not well known, hydatid cysts from the liver and the mesentery were examined from patients following surgical procedures. Whole mounts of protoscoleces with rostellar hooks were examined under light and confocal laser scanning microscopy. Measurements were made of both large and small hooks, including the total area, total length, total width, blade area, blade length, blade width, handle area, handle length and handle width. The results confirmed the 1:1 arrangement of hooks in the rostellar pad and indicated, for the first time, that the morphometry of large and small rostellar hooks varies depending upon the site of infection. Light and confocal microscopy images displayed clusters of calcareous corpuscles in the protoscoleces. In conclusion, morphological features of large and small rostellar hooks of E. vogeli are adapted to a varied environment within the vertebrate host and such morphological changes in calcareous corpuscles occur at different stages in the maturation of metacestodes.

Although sheep farming has grown in the state of Acre over the past four decades, little is known about occurrences of helminthiases in the herds of this region. The objective of the study was to assess the occurrences of non-intestinal helminthiasis among sheep slaughtered in Rio Branco. A total of 110 sheep livers were inspected from two slaughter batches (july 2014 and march 2015) in a slaughterhouse in Rio Branco. Livers with macroscopic lesions were photographed and were then subjected to histopathological analysis under an optical microscope. The macroscopic lesions showed small nodes with inflammatory characteristics and areas of fibrosis, which appeared to be calcified, thus suggesting a granulomatous reaction. Of the 110 evaluated livers, we noticed 110 nodules in total; these nodules have an average size of 0.5 cm. The histopathological analysis showed alterations to the architecture of the hepatic lobe, with multiple foci of necrosis and polymorphonuclear cells. Two samples revealed the presence of helminths from Nematode class and Capillaria sp. eggs identified by the typical morphology and morphometry. This seems to be the first report of Capillaria sp. in sheep livers in Brazil, and it serves as an important alert regarding animal health surveillance and control and regarding the Capillaria sp. zoonotic role in humans.