Assessing Cryptosporidium presence in pet owned and introduced non-native freshwater turtles in the UK

Abstract Purpose Introduced non-native species are recognised as a reservoir for zoonotic transmission, posing risks to both wildlife and humans. The presence of Cryptosporidium spp. (protozoan parasite) has not been previously studied in rehomed or feral pet freshwater turtles in the UK. These animals may pose risks to pet owners when carrying out husbandry activities and if released/escaped could further contribute to pathogen pollution in the wild. Methods Between 2021–2023, both pre-owned and introduced turtles were housed temporarily for a period of 14 days in separate holding containers. In total, 77 faecal samples were collected: turtles brought for rehoming by pet owners (n = 35) and non-native turtles removed from fresh waterbodies across England (n = 42). Faecal samples were initially tested using quick stick assays. The DNA was then extracted from samples, and both PCR and Sanger sequencing were carried out to identify Cryptosporidium presence. Results In total, 57 (74%) samples tested PCR positive for Cryptosporidium . Although there were a high number of positive PCR results, only 2 (5%) tested positive from further Sanger sequencing. These were two separately rehomed pet Pseudemys spp. (cooter turtles), Cryptosporidium ryanae and C. parvum . C. ryanae , is a bovine intestinal parasite of low pathogenicity rarely causing critical illness therefore the individual sampled is assumed an asymptomatic mechanical vector. However, C. parvum was identified in a pet turtle brought for rehoming. C. parvum being a highly pathogenic zoonotic parasite causing severe to fatal clinical outcomes in young and immunocompromised. This may pose a risk to pet owners and pathogen pollution as a result of release into the wild. Conclusion Although the parasite was found present, the results imply a low risk of transmission. Further investigation is suggested to understand the possible impacts on native wildlife and humans as a result of introduced pet turtles.