Esquistossomose: nova ocorrência de Biomphalaria straminea em Belo Horizonte, Minas Gerais

Abstract

In Belo Horizonte, Minas Gerais, Brazil, the snail Biomphalaria straminea was found in the Pampulha region. Recently the snail was found in ditches in the old Santa Lúcia Reservoir, a now-extinct focus of schistosomiasis transmission by B. glabrata. The snails were collected and examined to verify whether they were naturally infected with Schistosoma mansoni. Negative specimens were used for breeding or infection with the LE strain of S. mansoni from the laboratory and another strain obtained from eggs found in the feces of a schoolchild (VGS) from Belo Horizonte. Among the 1890 snails collected from 1994 to 1995, none were infected with S. mansoni. Among 87 snails collected and exposed to the LE strain, 9 (10.3%) shed cercariae; among 83 snails from F1, and exposed to LE, 10 (12.0%) shed cercariae. Among 88 snails exposed to VGS, 10 (11.3%) shed cercariae. In Belo Horizonte, schistosomiasis is transmitted by B. glabrata and B. tenagophila. However, currently there exists the risk of appearance of a focus in which B. straminea could be the host if prophylactic measures are not taken by the authorities responsible for the construction of a park and lake at that site.

Susceptibility of Biomphalaria straminea from Peixe Angical dam, Tocantins, Brazil to infection with three strains of Schistosoma mansoni

“…Infection indexes up 10%, such as those found in the population from the Tocantins River (12 o 46'52.5"S 48 o 14'11.7"W), have been reported for B. straminea specimens from other states: Pará (Paraense 1967), MG (Souza et al 1996), Piauí (Fernandez 1997), Alagoas, Ceará, Paraíba, PE and RN (Barbosa & Figueiredo 1970). According to Wright et al (1973), B. straminea is the most successful species and is a much more important host than B. glabrata in Northeastern Brazil because it is well adapted to all climatic varieties, inhabiting both permanent and temporary bodies of water.…”

The Pampulha reservoir remains a potential urban focus of schistosomiasis mansoni in Brazil: changes in the occurrence patterns of Biomphalaria species and a new record of the parasite

“…Although their current relevance in the transmission of the parasite in southeastern and west-central Brazil appears to be minimal, the presence and growth of B. straminea in localities from these regions around Brazil are associated with environmental and social changes related to the epidemiology of schistosomiasis and should serve as a warning. It is possible that this species may become epidemiologically important in the transmission of parasites in these regions in the future [24][25][26][27] . This species was fi rst reported in Belo Horizonte at the Pampulha basin (in the Baraunas stream) in the early 1980s 28 , and until the early 1990s, it remained restricted to the introduction site and was not verifi ed within the reservoir 29 .…”

Moluscos límnicos da microrregião de Belo Horizonte, MG, com ênfase nos vetores de parasitoses

“…From 1990to 1996 were found infected by trematodes: Biomphalaria glabrata (7,920), infected by Schistosoma mansoni (1.9%), Echinostomatidae (1.2%), Strigeidae (0.6%), C e r c a ria minense (0.1%) and Dero g e n i d a e ( -0.1%); B. s t ra m i n e a (4,093) infected by Strigeidae (0.6%), Echinostomatidae (0.2%), B. tenagophila (1,338), infected by Strigeidae (0.1%) and P hysa marm o ra t a …”

“…Eventualmente, em um criadouro ocorre a substituição de uma espécie hospedeira por outra 23 . Além dos focos de transmissão de esquistossomose, alguns autores tem registrado ainda as taxas de infe c ç ã o dos moluscos de água doce com larvas de outros trematódeos não só na microrregião de Belo Horizonte como em outras regiões do Estado 1 2 15 16 19 21 .…”