Monday, April 19, 2010

Amber Snails a Host for Liver Fluke?

The Amber Snails (Succineidae), are a family of snails with thin-walled, glossy translucent shells with large body-whorls and very short spires. They are typically found in wet habitats and some are amphibous. Five species are found in Ireland, such as Oxyloma pfeifferi, Pfeiffer's Amber Snail, pictured below. O. pfeifferi has in fact been identified as a major pest of hardy nursery stock by horticulturalists, with losses of €3.5 - 4 milion being reported (Schuder et al., 2004 Crop Protection 23 pp. 945–953).

Pfeiffer's Amber Snail, Oxyloma pfeifferi

Succineidae have also been identified as another potential risk to another agricultutal sector. The liver fluke, Fasciola heptica, is an internal parasite of livestock that causes €25 million worth of loss to Irish farmers yearly with deaths and lost production, due to lowered weight gains, milk production and fertility. In 2008, deaths due to acute and chronic fasciolosis accounted for 20.5% of diagnosed causes of death in adult sheep in Ireland (Irish Regional Veterinary Laboratories Surveillance Report 2008). F. hepatica requires an intermediate molluscan host to complete its life cycle and worldwide species from the genera Lymnaea, Galba, Pseudosuccinea and Stagnicola act as these hosts. In Ireland and the UK the water snail Galba truncatula is the recognised host of F. hepatica. However, a study by Relf et al. in 2009 (Veterinary Parasitology 163 pp. 152–155) discovered a Succineid as an alternative intermediate host of F. hepatica. They found that in a hill and mountain grazing system, where the acidic soil conditions would not support populations of G. trunculata due to sufficient calcium for shell developement, infection among the sheep herd was 63.6%. Using PCR analysis of cytochrome c oxidase subunit 1 gene of F. hepatica, 79% samples of the same Succineid species showed presence of the fluke.

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