A molecular and ecological analysis of the trematodePlagiorchis elegansin the wood mouseApodemus sylvaticusfrom a periaquatic ecosystem in the UK

Abstract

The prevalence of the digenean Plagiorchis sp. was investigated in a natural wood mouse population (Apodemus sylvaticus) in a periaquatic environment. Classical identification was complemented with the use of molecular differentiation to determine prevalence and verify species identity. Use of the complete ITS1-5.8S rDNA-ITS2 and partial 28S rDNA gene sequences have confirmed that the species reported at this location was Plagiorchis elegans and not Plagiorchis muris as reported previously. This underlines the difficulties in identification of these morphologically similar parasites. Plagiorchis elegans is typically a gastrointestinal parasite of avian species but has also been reported from small mammal populations. Although the occurrence of this digenean in A. sylvaticus in the UK is rare, in the area immediately surrounding Malham Tarn, Yorkshire, it had a high prevalence (23%) and a mean worm burden of 26.6 ± 61.5. The distribution of P. elegans followed a typically overdispersed pattern and both mouse age-group and sex were determined to be two main factors associated with prevalence. Male mice harboured the majority of worms, carrying 688 of 717 recovered during the study, and had a higher prevalence of 32.4% in comparison to only 8.7% in the small intestine of female mice. A higher prevalence of 43% was also observed in adult mice compared to 14% for young adults. No infection was observed in juvenile mice. These significant differences are likely to be due to differences in the foraging behaviour between the sexes and age cohorts of wood mice.

Plagiorchis sp. in small mammals of Senegal and the potential emergence of a zoonotic trematodiasis

“…Sequencing of the ITS region proved to be useful for characterising Plagiorchis spp. (Tkach et al, 2000; Boyce et al, 2014), while the simultaneous examination of rDNA and mtDNA loci is suitable for molecular prospecting and further hypothesis testing on species delimitation (Nadler and Pérez-Ponce de León, 2011). Our findings revealed that Plagiorchis isolates from M. huberti , A. niloticus , and Crocidura sp., represented the same evolutionary lineage.…”

“…Due to time constraints, the gastrointestinal tract was analysed for a randomly-selected subset of the hosts. Isolated trematodes were characterised to the genus level based on their morphology using an Olympus CX41 microscope (following Boyce et al, 2014), counted to determine infection intensity (counts stopped at 61 individuals due to time constraints, therefore higher intensities are referred to as > 61 and the value 62 was used in statistical analyses), and preserved in 95% ethanol at −20 °C. Samples of liver from infected and uninfected M. huberti were preserved in 10% neutral-buffered formalin followed by routine processing for histopathological examination.…”

“…Trematodes of the genus Plagiorchis have a heteroxenous life cycle involving freshwater pulmonate gastropods of the family Lymnaeidae as first intermediate hosts and mosquito and chironomid larvae, insect naiads, freshwater fish, and crustaceans as second intermediate hosts (Guk et al, 2007; Boyce et al, 2014; Soldánová et al, 2017). Plagiorchis spp.…”

“…are cosmopolitan, their vast distribution spanning from boreal to tropical zones around the globe. Their wide geographic range may be a consequence of their relatively low host specificity, with records of adult parasites of the genus Plagiorchis from the small intestine of a variety of definitive hosts, including reptiles, birds, and mammals (Guk et al, 2007; Boyce et al, 2014).…”

“…were first described, with few human cases and one report on P. harinasutai infecting rodents in the Republic of the Philippines (Radomyos et al, 1998; Eduardo and Lee, 2006). However, the taxonomic validity of these records may be questionable since the identification of Plagiorchis isolates was based solely on morphological traits, which lack diagnostic accuracy due to their high intra-specific variability (e.g., Brendow, 1970; Tkach et al, 2000; Boyce et al, 2014; Zikmundová et al, 2014).…”