The bioecology of snail vectors for schitosomiasis in Brazil

Abstract

This paper describes the ecology of two species of Biomphalaria: B. glabrata and B. straminea. These species have been intensively studied in Brazil and in other countries since the 1950s. The literature in this area can be broadly subdivided into three categories, linked to three distinct historical periods: 1) an accumulated store of early studies carried out in the laboratory and in the field; 2) the development of quantitative ecological models; and 3) the development of an alternative methodology for breeding snails under seminatural conditions.

Assessment of schistosomiasis, through school surveys, in the Forest Zone of Pernambuco, Brazil

“…The emphasis has been on the ecology and control of the mollusks that are the intermediate hosts (Barbosa 1992a,b, 1996, Barbosa & Barbosa 1994, 1996, Barbosa et al 1992, 1993, Bogéa et al 1996, Dannemann & Pieri 1989, 1991, 1993a, b, Favre et al 1995, 1997, Gazin et al 2000, Pieri 1995, Pieri & Dannemann 1996, Pieri & Thomas 1986, 1987, Randall et al 2001, Sarquis et al 1997, the ecological and epidemiological determinants of the disease (Barbosa 1992b, 1997, 1998a, b, Barbosa & Coimbra 2000, Barbosa & Gouveia 2000, Coutinho et al 1997, Gazin et al 2002, Gonçalves et al 1992, Simões-Barbosa et al 2001, and also the impact of chemotherapy treatment for infected individuals, in relation to the transmission dynamics of the disease , Favre et al 2002, Zani et al 2004). The knowledge resulting from these studies has made it possible to adapt the schistosomiasis evaluation and control strategies recommended by central health bodies -WHO at the worldwide level and the Health Surveillance Department of the Ministry of Health at the national level -to the regional characteristics and demands.…”

Modelling of the distribution of Biomphalaria glabrata and Biomphalaria straminea in the metropolitan region of Recife, Pernambuco, Brazil

“…The hot season is most favourable for snail reproduction as it increases the microflora, which serves as an important nutritional source, while aquatic plants provide adequate dissolved oxygen and surface where the snails can crawl and deposit their egg masses (Malek, 1958). Increase in temperature also stimulates the release of cercariae (Lutz, 1919;Rey, 2008) with the optimum temperature for snail development is between 20 and 26°C (Barbosa and Barbosa, 1994), but temperatures from 18 to 41°C can be tolerated (Brazil, 2008). Rainfall influences the formation and expansion of snail breeding sites/foci (Barbosa and Barbosa, 1994).…”

“…Increase in temperature also stimulates the release of cercariae (Lutz, 1919;Rey, 2008) with the optimum temperature for snail development is between 20 and 26°C (Barbosa and Barbosa, 1994), but temperatures from 18 to 41°C can be tolerated (Brazil, 2008). Rainfall influences the formation and expansion of snail breeding sites/foci (Barbosa and Barbosa, 1994). In the rainy season (May to August), Biomphalaria spp.…”

“…It is directly influenced by the environment in which it lives and has developed a variety of survival strategies (Brazilian Ministry of Health, 2014). These snails' habitats consist exclusively of freshwater bodies with little water velocity (less than 30 cm/sec), such as rivers, streams, channels and flooded areas, preferably with little depth (Barbosa and Barbosa, 1994;Pieri and Favre, 2008). There are even reports of the existence of these snails in puddles, drains and flooded, vacant land (Barbosa et al, 2001(Barbosa et al, , 2004Silva et al, 2006;Souza et al, 2008).…”

Changes in energetic metabolism of Biomphalaria glabrata (Mollusca, Planorbidae) in response to exogenous calcium

“…Biomphalaria glabrata (Say, 1818), the main intermediate host of Schistosoma mansoni Sambon, 1907 in Brazil, is a model for ecologic, toxicological and parasitological studies, since it occupies a high trophic level and is a food resource for several organisms (Barbosa and Barbosa, 1994;Paraense, 1970). Snails are good bioindicators of contamination of freshwater environments (Cantinha et al, 2010;Carvalho et al, 1988), as they are sensitive to environmental alterations, such as chemical elements dissolved in the water, hydrography, soil composition, climate and physical geography (Abílio et al, 2007;Guerino et al, 2009).…”