Endemic Occurrence Offasciola Hepaticain An Alpine Ecosystem, Pyrenees, Northeastern Spain

Fasciola hepaticais a liver parasite of ruminants whose distribution is determined by its intermediate host, the freshwater snailGalba truncatula. In Europe,F. hepaticais mostly associated with lowlands. Infection from sympatric domestic reservoirs is rarely reported in wild mountain ungulates. This study exploresF. hepaticain a multi-host system in a European alpine area. Serum samples (n = 1,209) from Pyrenean chamois (Rupicapra p. pyrenaica), European mouflon (Ovis aries musimon), domestic sheep (Ovis aries) and domestic cattle (Bos taurus) were collected in the National Game Reserve of Freser-Setcases (NGRFS) in Catalonia, Northeastern Spain, from 2008 to 2019, and tested for antibodies againstF. hepatica. During the same period, the livers of 214 chamois hunted in the NGRFS were inspected forF. hepaticaand associated pathological changes. Finally, 907 freshwater snails were collected in summer 2016 between 1559 and 2,224 metres above sea level (asl) in the NGRFS, andF. hepaticaDNA sought by PCR. Antibodies againstF. hepaticawere detected in all four species, with a higher prevalence in cattle and sheep than in chamois.Fasciola hepaticaand hepatic lesions were concurrently observed in 13/214 of the chamois livers inspected (6.1%, CI95 2.9%-9.3%).Fasciola hepaticaDNA was detected in one out of the 907 snails (0.1%, Cl95 0.1% - 0.3%; Ct value 33.3) and collected at 2054 m asl.Fasciola hepaticawas consistently detected in a high mountain multi-host system, suggesting that its life cycle is completed and that it occurs endemically at the highest elevation reported in Europe. Transhumant livestock are the likely source in this alpine ecosystem, which according to rare occurrence ofF. hepaticaDNA inG. truncatulais still a suboptimal habitat forF. hepaticalife cycle. Studying parasites at their highest distribution range can be useful to monitor climate change in seasonal mountain environments.