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

As part of surveillance of snail-borne trematodiasis in Knowsley Safari (KS), Prescot, United Kingdom, a collection was made in July 2021 of various planorbid ( = 173) and lymnaeid ( = 218) snails. These were taken from 15 purposely selected freshwater habitats. In the laboratory emergent trematode cercariae, often from single snails, were identified by morphology with a sub-set, of those most accessible, later characterized by cytochrome oxidase subunit 1 ( 1) DNA barcoding. Two schistosomatid cercariae were of special note in the context of human cercarial dermatitis (HCD), emergent from and spp. emergent from . The former schistosomatid was last reported in the United Kingdom over 50 years ago. From 1 analyses, the latter likely consisted of two taxa, , a first report in the United Kingdom, and a hitherto unnamed genetic lineage having some affiliation with . The chronobiology of emergent cercariae from was assessed, with the vertical swimming rate of measured. We provide a brief risk appraisal of HCD for public activities typically undertaken within KS educational and recreational programmes.