Fauna malacológica dulcícola e identificação de larvas de trematódeos em região endêmica para fasciolose no sul do Espírito Santo

Abstract

The digenetic trematode Fasciola hepatica is a parasite with the potential to cause significant losses in ruminant herds, also presenting a high zoonotic potential with aquatic snails being intermedial hosts. This study aimed to recognize the malacological fauna and identify trematodes larval types in endemic areas for fasciolosis in the southern region of Espírito Santo, as well as to correlate determining factors for the occurrence of the disease. The analysis of properties with a history of fasciolosis was conducted by collecting data from the Parasitology Laboratory of UFES, covering the period from 2020 to 2022. A visit was made to 10 properties, where all aquatic snails present were collected and identified. For the recovery of cercariae in the laboratory, snails were tested every 10 days for 4 hours using photo-stimulation. The identification of cercariae was based on morphological characteristics, and there was also histological processing of positive snails for the visualization of other larval forms. Ten properties were identified as positive for the presence of F. hepatica. The species of snails found in the region were P. columella, B. glabrata, M. tuberculata, and S. marmorata. The types of cercariae emerging from the snails were xiphidiocercariae and echinostomes, with no cercariae of Fasciola found. During histological analysis, a large number of sporocysts were observed in the tissues of P. columella individuals, as well as internal structures similar to cercariae in the vesicles. In the multivariate analysis, it was found that the factors that most influenced the results were the number of examinations carried out on the properties and the number of animals diagnosed as positive for fasciolosis. The data indicate that geographic distribution, property characteristics, and the presence of snails play a significant role in the dissemination of cercariae in the hydrographic network