Analysis of the life cycle of Calicophoron daubneyi under controlled laboratory conditions

• Applicants: Professorin Dr. Gabriela Knubben; Professor Dr. Markus Meißner
• Subject Area: Veterinary Medical Science ; Parasitology and Biology of Tropical Infectious Disease Pathogens
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559306076

Infections by parasitic flukes are a major concern for livestock producers worldwide. While in the past the liver fluke Fasciola hepatica has been a focus of livestock farmers and consequently research, in recent years the occurrence of paramphistomidosis became a major concern. Here the rumen fluke Calicophoron daubneyi appears to be the predominant species in Europe. Importantly, C. daubneyi and F. hepatica share the same intermediate host, the dwarf pond snail Galba truncatula, causing often co-infections of cattle with both parasites because of the same transmission ecology. The reasons for the sharp increase in rumen fluke infections remain to be determined and climate change, causing environmental conditions more beneficial for C. daubneyi leading to outcompetition of F. hepatica by C. daubneyi are possibilities that await further characterisation. However, currently no experimental system has been established to investigate the whole life cycle of C. daubneyi under well defined, experimental conditions. During the past four years, we succeeded to establish the whole life cycle of C. daubneyi (Wenzel et al. 2024). Briefly, a stable culture of G. truncatula that can be kept under defined conditions has been established and can now be used for infections with miracidia, experimentally derived from eggs. Infected snails reproducibly shed cercariae that developed into viable metacercariae, which were used to infect lambs. Finally, identified eggs were shed from adult rumen flukes, closing the whole life cycle. Importantly, the same system has been used to generate cercariae for F. hepatica, proving that the same snail culture and the same experimental conditions can be used to analyse and compare infections with both flukes. Therefore, this breakthrough allows us for the first time to investigate and compare both life cycles in a laboratory in parallel to address the following questions: 1. Analysis and comparison of intermediate snail host identification and invasion between C. daubneyi and F. hepatica 2. Biochemical identification and isolation of intermediate host-factors triggering chemotaxis of miracidia. 3. Analysis of development of C. daubneyi and F. hepatica in the intermediate host under defined laboratory conditions. 4. Who will win: Analysis of Co-Infections with C. daubneyi and F. hepatica.

• DFG Programme: Research Grants