Institute for Fish and Wildlife Health


Trypanosomiasis: An Emerging Disease in Alpine Swifts in Switzerland?

In the summer of 2022, unexpectedly high numbers of sudden nestling mortalities occurred in multiple Alpine swift (Tachymarptis melba) colonies, despite overall favorable weather conditions and abundant food sources. 
The Swiss Ornithological Institute (VoWa), which has closely monitored the colonies since 1940, contacted the Institute of Fish and Wildlife Health (FIWI) for the mortality investigation. 

In collaboration with the Institute of Parasitology, an unusually high number of trypanosomes were detected in tissue and blood. This genetically undescribed species, is believed to be the cause of the mortalities at this point in the research.  Louse flies (Crataerina spp.) collected simultaneously from nestlings tested positive for the same parasite, indicating a possible function as a vector of the blood parasites. We conclude that trypanosomiasis is an emerging disease in alpine swifts in Switzerland, which strongly endangers the previously stable population due to massive mortality in nestlings.

These findings are highly significant, as avian trypanosomes are generally considered apathogenic, resulting in a low parasitaemia with no concurrent clinical signs. To better understand the host-pathogen interactions at play, the mechanisms behind the observed pathologies, and potential external factors, a research group consisting of the Institute of Fish and Wildlife Health, the Institute of Parasitology and the Swiss Ornithological Society has been formed to tackle these open questions.

Project Team

FIWI: Pia Cigler, Saskia Keller
Institute für Parasitology: Gastón Moré, Walter Basso
Swiss Ornithological Society: Pierre Bize, Christoph Meier


Swisslos Aargau
Swisslos Solothurn

Publications and Outputs

Cigler P, Moré G, Bize P, Meier C, Colominas R, Frey CF, Basso W, Keller S. 2023. Trypanosomiasis: An Emerging Disease in Alpine Swift (Tachymarptis melba) Nestlings in Switzerland? Presented at the Zoo and Wildlife Health Conference, Valencia, Spain

Cigler P, Moré G, Bize P, Colominas R, Meier C, Hemphill A, Frey CF, Keller S, Basso W. 2023. Infections with Trypanosoma sp. and Crataerina spp. associated with an increased mortality rate in alpine swifts (Tachymarptis melba). Presented at the DVG-Fachgruppe "Parasitologie und parasitäre Krankheiten", Münich, Germany 

Moré G, Bize P, Cigler P, Colominas R, Hemphill A, Keller S, Frey CF, Basso W. 2023. Crataerina spp. as potential vectors for a Trypanosoma sp. in Alpine swifts? Presented at the Swiss Vector Entomology Group Scientific Meeting, Zürich, Switzerland