Geographic distribution modelling for ruminant liver flukes (Fasciola hepatica) in south-eastern Europe

doi:10.1016/j.ijpara.2011.01.006

International Journal for Parasitology

Volume 41, Issue 7, June 2011, Pages 747-753

https://doi.org/10.1016/j.ijpara.2011.01.006 Get rights and content

Abstract

Maximum entropy ecological niche modelling was utilised to predict the geographic range for fluke genotypes and haplotypes in south-eastern Europe, using the Maxent program. The lowest (0.832) and the highest (0.947) area under the curve values were observed in the models for the haplotypes CtCmt1 and CtCmt2.2, respectively. Precipitation and temperature contribute equally to model building of the genotypes based on the 28S rDNA gene. In regard to the mtDNA gene region, precipitation is the most important factor in modelling the CtCmt1 haplotype range, while temperature appears to be the most important factor in modelling the CtCmt2.1 and CtCmt2.2 haplotype ranges. The highest level of probability for the geographic distribution of Fasciola hepatica genotypes and haplotypes covered the regions of southern Bulgaria and central and northern Greece which contain a high concentration of potential ruminant hosts.

Graphical abstract

Research highlights

► Precipitation and temperature affect the range of genotypes of the 28S rDNA gene of Fasciola hepatica. ► Precipitation affects the range of the CtCmt1 haplotype of the mtDNA gene. ► Temperature affects the range of the CtCmt2.1/CtCmt2.2 haplotypes of the mtDNA gene.

Introduction

Fasciola hepatica is a liver fluke parasite of ruminants and is endemic in many parts of the world (Mas-Coma et al., 2005). Many studies have investigated the genetic diversity of this parasite (Hurtrez-Bousses et al., 2004, Lee et al., 2007, Erensoy et al., 2009). The Single Nucleotide Polymorphism (SNP) assay has been used to determine the diversity within the partial 28S ribosomal deoxyribonucleic acid (rDNA) gene of F. hepatica (Marcilla et al., 2002, Semyenova et al., 2005) and in partial mtDNA (Semyenova et al., 2006, Walker et al., 2007). The presence of two main lineages was proposed by Semyenova et al. (2006) for fluke populations in eastern Europe and the presence of three clades was proposed by Walker et al. (2011) for fluke populations in the Netherlands.

On the basis of the genetic diversity among the fluke populations from Poland, Bulgaria and Greece, there is a distinct geographical trend in polymorphisms in eastern Europe in a south–north direction (Teofanova et al., 2011). This observation indicates that each lineage may occur in distinct geographical areas.

Reports on the distribution of F. hepatica genotypes are unavailable in south-eastern Europe. Ecological niche modelling offers the opportunity to derive predictive distribution maps from species or genotype occurrence and environmental data (Phillips et al., 2006, Masuoka et al., 2009, Kouam et al., 2010). As a trematode, F. hepatica spends most of its life cycle in either its definitive or intermediate host and is only exposed to environmental conditions for short and specific stages in its life cycle, as a miracidium or cercaria. Therefore, modelling the distribution of F. hepatica genotypes is largely modelling the conditions for the presence of its definitive and intermediate hosts.

In the present study a cross-sectional survey was conducted in Greece and Bulgaria to collect information on the spatial distribution of F. hepatica genotypes and haplotypes in order to construct predictive maps for Greece and Bulgaria of different F. hepatica genotypes and haplotypes, based on ecological niche modelling.

Section snippets

Occurrence localities database

A total of 204 F. hepatica flukes were collected from 31 sheep and three cattle in abattoir surveys from various areas of mainland Greece (Evros, Rodopi, Kavala, Pieria, Larissa, Karditsa, and Thesprotia) and six cattle from various areas of Bulgaria (Sofia, Kostinbrod, Byala Slatina, Yakoruda, Belitsa, and Bansko) (Fig. 1) between 2005 and 2007. The genotypes and haplotypes of the flukes were determined by the study of SNPs from partial regions of both the nuclear gene of the 28S rDNA (b105A

Results

Fig. 2 displays the potential geographic distribution of F. hepatica genotypes predicted by the Maxent program. The highest level of probability (P > 0.61) for the geographic distribution of genotype b105A (Fig. 2A) and b105G (Fig. 2B), respectively, covers the central part of Greece (Thessaly), extends to northern Greece and spreads towards north-eastern Greece and southern Bulgaria.

The range with the highest probability (P > 0.61) for the presence of the CtCmt1 haplotype includes the

Discussion

Ruminants are an important source of income for the economy of south-eastern Europe, with approximately 14 million animals spread over Greece and more than 2 million in Bulgaria (http://epp.eurostat.ec.europa.eu/portal/page/portal/agriculture/data/database). The prevalence of fasciolosis in Greece has been reported to be 0.4% in cattle and 0.1% in sheep (Theodoropoulos et al., 2002). Sporadic cases have also been reported in humans in Greece (Archimandritis et al., 1976). The present study

Acknowledgment

This work was supported by the European Union funded DELIVER Project (Contract No.: FOOD-CT-2004-023025).

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Geographic distribution modelling for ruminant liver flukes (Fasciola hepatica) in south-eastern Europe

Abstract

Graphical abstract

Research highlights

Introduction

Section snippets

Occurrence localities database

Results

Discussion

Acknowledgment

Int. J. Parasitol.

Adv. Parasit.

Vet. Parasitol.

Vet. Parasitol.

Int. J. Parasitol.

Infect. Genet. Evol.

Mol. Cell. Probes

Int. J. Parasitol.

Vet. Parasitol.

Int. J. Parasitol.

Acta Ecol. Sin.

Ecol. Model.

Ecol. Model.

Infect. Genet. Evol.

Vet. Parasitol.

Liver fascioliasis, a “mysterious” disease. Report of a case

Acta Hepatogastro.

Bridging gaps in the molecular phylogeny of the Lymnaeidae (Gastropoda: Pulmonata), vectors of fascioliasis

BMC Evol. Biol.

Novel methods improve prediction of species’ distribution from occurrence data

Ecography

Genetic identification of Fasciola hepatica by ITS-2 sequence of nuclear ribosomal DNA in Turkey

Parasitol. Res.