Introduction: Swimmer's itch (or cercarial dermatitis) is caused by avian and mammalian blood flukes, a parasitic infection affecting people worldwide. In particular, avian blood flukes of the genus Trichobilharzia, including Trichobilharzia regenti, are known for causing swimmer's itch. While these parasites typically infect waterfowl as final hosts, incidental infections in humans by cercariae can occur. Such infections trigger immune responses leading to painful, itchy skin lesions. In experimental animals, T. regenti has however shown the ability to evade immune responses, causing neuroinflammation. Recent decades have witnessed an increase in swimmer's itch cases across Europe, turning it into an emerging zoonosis. Methods: Following a swimmer's itch case in Kampenhout (Belgium) in 2022, a malacological and parasitological survey was conducted at the transmission site, consisting of a private pond and adjacent creek. Results: Six snail species were collected, including Ampullaceana balthica, a common intermediate host for Trichobilharzia parasites. Shedding experiments and DNA barcoding identified one snail specimen infected with T. regenti, a new species record for Belgium. This finding further strengthens the link between T. regenti and cercarial dermatitis. Additionally, Echinostomatidae sp. and Notocotylus sp. were isolated from other A. balthica specimens. However, the absence of reference DNA sequences hindered genus- and species-level identification for these parasites. Conclusions: The presence of T. regenti in Belgium may have significant clinical implications, emphasizing the need for heightened diagnostic awareness among medical professionals. The lack of species-level identification for other parasite species underscores the need for comprehensive DNA databases for trematodes. These findings reveal the necessity for a Belgian framework to promptly detect and monitor zoonotic outbreaks of trematode parasites within the One Health context.
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RBINS Staff Publications 2025
Biological invasions represent a significant threat to global biodiversity, impacting ecosystems and altering ecological dynamics. The introduction of the Nile perch (Lates niloticus) into Lake Victoria (East Africa), has led to ecological transformations, influencing the native fish communities. While much attention has been devoted to studying the ecological impacts of the Nile perch invasion on the native fish fauna and socio-economic consequences, little is known about the co-introduction dynamics of its potentially co-invasive parasites, as well as the impact on the gill macroparasite fauna of the native fishes impacted by the invasion (e.g. haplochromine cichlids). To investigate the co-introduction dynamics, we assessed the genetic and morphological diversity of Dolicirroplectanum lacustre, the only flatworm (Monogenea) parasite that infects lates perches across Africa. We found that D. lacustre was co-introduced with L. niloticus. In Lake Victoria, we found a reduction in the genetic and morphological diversity of D. lacustre compared with its native range, indicating a founder effect. To examine the broader ecological consequences of Nile perch invasion and human-induced eutrophication, we compared gill macroparasite communities of 13 native haplochromine cichlid species before and after these perturbations. We observed a reconfiguration of the host-parasite network that buffers the impacts of perturbations, indicating resilience. However, we observe a decrease in parasite-host range and infection parameters, highlighting the vulnerability of parasite communities to ongoing environmental changes associated with biological invasions. These findings underscore the importance of understanding the intricate dynamics of host-parasite interactions in the context of biological invasions and environmental change. By integrating insights from the invasive species dynamics and ecological perturbations, we provide valuable insights into the challenges and opportunities for conservation efforts to preserve ecosystem health and resilience in the face of global change.
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RBINS Staff Publications 2024
