The genus Bilharziella vs. other bird schistosomes in snail hosts from one of the major recreational lakes in Poland

Abstract

Bird schistosomes are commonly established as the causative agent of swimmer's itch − a hyper-sensitive skin reaction to the penetration of their infective larvae. The aim of the present study was to investigate the prevalence of the genus Bilharziella in comparison to other bird schistosome species from Lake Drawsko − one of the largest recreational lakes in Poland, struggling with the huge problem of swimmer's itch. In total, 317 specimens of pulmonate snails were collected and examined. The overall digenean infection was 35.33%. The highest bird schistosome prevalence was observed for Bilharziella sp. (4.63%) in Planorbarius corneus, followed by Trichobilharzia szidati (3.23%) in Lymnaea stagnalis and Trichobilharzia sp. (1.3%) in Stagnicola palustris. The location of Bilharziella sp. on the presented phylogeny showed that it is with high probability a different species than known so far B. polonica. Our finding complements the confirmed occurrence of bird schistosomes in European water bodies. Overall, presented research reveals the special importance of P. corneus as a source of the bird schistosome cercariae. This study suggests that the health threat connected with the blood flukes need to be further investigated by constant monitoring of their occurrence in intermediate hosts.

A report of Bilharziella polonica cercariae in Knowsley Safari, Prescot, United Kingdom, with notes on other trematodes implicated in human cercarial dermatitis

“…As proposed by Loker et al (2022), with further genetic scrutiny of emergent cercariae additional novel cox 1 lineages of Trichobilharzia will appear. This has also recently occurred with increased B. polonica cox 1 lineage sampling (Stanicka et al , 2021). Two decades ago, Kolárová et al (1999) described T. anseri upon morphological features of cercariae which was then linked with an official description of T. anseri (Jouet et al , 2015).…”

“…Indeed, relatively little is known about this trematode and its natural history (Loker et al , 2022). For example, a recent molecular epidemiological study from one of the major recreational lakes in Poland has suggested the presence of a cryptic Bilharziella sister species, which is not surprising given the general lack of targeted surveillance for this trematode (Stanicka et al, 2021). Our report here hopes to stimulate some further interest and better awareness in the United Kingdom about this rather rare trematode.…”