Sympatric and allopatric combinations of Lymnaea columella and Fasciola hepatica from southern and south-eastern Brazil L.H.L. Coelho*, W.S. Lima and M.P. Guimaraes Departamento de Parasitologia, Instituto de Cie ˆncias Biolo ´ gicas, Universidade Federal de Minas Gerais, Avenida Anto ˆ nio Carlos 6627, CEP 31270-901 Belo Horizonte, Minas Gerais, Brazil Abstract Experimental infections of Lymnaea columella with Fasciola hepatica were carried out to test the effect of sympatric and allopatric combinations between parasite and host, by using snails and flukes from southern and south-eastern Brazil. Four groups of 50 snails were infected with four miracidia per snail: two groups in sympatric and two groups in allopatric combinations. Sympatric combi- nations between parasite and host were more efficient than allopatric ones when snails from Itajuba ´ were used, but the opposite was observed in infections involving snails from Pelotas. The sympatric association between L. columella and F. hepatica from Itajuba ´ was significantly higher than in the other combinations. We concluded that the host – parasite relationship between L. columnella and F. hepatica may vary according to the geographical origin of the snails and flukes involved. Introduction Members of the genus Lymnaea are hermaphrodite pulmonate gastropods with dextrally coiled shells lacking operculi. The genus has a cosmopolitan distribution and approximately 40 species are known worldwide (Hubendick, 1978). These snails are the intermediate hosts of Fasciola hepatica and play an important role in the epidemiology of fascioliasis. Various studies have reported that geographical variation influences the susceptibility of Lymnaea spp. to infection by F. hepatica; that is, in the development of the life cycle stages of this parasite in the snail (Dacal et al., 1988; Gasnier et al., 2000; Goumghar et al., 2001) or snail survivorship (Vignoles et al., 2001). Brazil has an area of 8,514,877 km 2 and is divided into eight regions and 26 states with a variety of different climates and topographies. Bovine fascioliasis is caused by F. hepatica, as the presence of F. gigantica has not yet been reported in the country. It occurs principally in the southern, south-eastern and midwestern regions of the country (Coelho & Lima, 2003; Faria et al., 2005). The geographical distribution of the three known lymnaeid snails (L. columella, L. viatrix and L. cubensis) is wide, the first of these species being the intermediate host of F. hepatica in southern and south-eastern Brazil (Paraense, 1982a, b, 1983, 1986; Amato et al., 1986; Coelho & Lima, 2003; Mas-Coma et al., 2005; Cardoso et al., 2006). The south-eastern state of Minas Gerais is one of the principal cattle-raising states of the country, with nearly 20 million head of cattle distributed within an area of 586,000 km 2 . Only isolated cases of fascioliasis have been reported from this state, with the municipality of Itajuba ´ having the highest prevalence (Coelho & Lima, 2003; Faria et al., 2005). The dispersal of fascioliasis to other areas is influenced by the transport of infected animals and depends on the populations of Lymnaea present in these localities. The geographical race to which parasites and hosts belong may influence the result of infections. Associations may be sympatric if the hosts and parasites are from the same area, or allopatric if they involve parasites and hosts from different localities (Goumghar et al., 2001). The influence of sympatric and allopatric host – parasite associations has been investigated in other countries (Gasnier et al., 2000; Goumghar et al., 2001) but there have been no studies investigating this effect in snail populations from distinct regions of Brazil. The objective of this study was to *E-mail: ewjh2001@yahoo.com.br Journal of Helminthology (2009) 83, 285–288 doi:10.1017/S0022149X09222930 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0022149X09222930 Downloaded from https://www.cambridge.org/core. IP address: 54.191.40.80, on 14 Jul 2017 at 12:47:54, subject to the Cambridge Core terms of use, available at