Presence of gastrointestinal and bronchopulmonary parasites in Cantabrian brown bears

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The Cantabrian brown bear (Ursus arctos) population is threatened although in a constant process of recovery during the last 20 years. Since data on the parasitological status of this bear is still limited, the objective of the present study was to assess the diversity and prevalence of parasites in this population. Thus, 111 bear faecal samples were collected in north-western Spain and analysed for estimating the occurrence of gastrointestinal and bronchopulmonary parasites. Samples were processed by flotation in saline and sucrose solution, sedimentation and Baermann-Wetzel techniques. In addition, a commercial immunofluorescent assay was performed for detecting Giardia duodenalis and Cryptosporidium spp. Dicrocoelium dendriticum was the most prevalent parasite (58.6%), followed by Baylisascaris transfuga (43.2%) and nematodes of the Suborder Strongylida (18.9%) and Spirurida (2.7%). Mixed infections were detected in the 41.4% of the samples. The presence of D. dendriticum was significantly highest in bears from the autonomous region of Castile and León as well as in those in which grass or nuts/acorns were the predominant food item. Moreover, the risk of being positive to B. transfuga was significantly higher during autumn–winter, and in those, faecal samples were mainly composed of fleshy fruit. Some of the parasites detected could infect other wildlife and even humans, and therefore, the risk of pathogen transmission deserves further investigation. Since the impact of endoparasites in the health status of bears is poorly understood, the establishment of a disease surveillance protocol is strongly recommended in order to assess the potential risk of these infections for bears.

Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This study has received funding from the Ministry of Ecological Transition and Demographic Challenge of Spain. It was also funded by the Program for consolidating and structuring competitive research groups (ED431C2023/16, Xunta de Galicia, Spain). J.V. López-Bao was additionally supported by the Spanish Ministry of Economy, Industry, and Competitiveness (CGL2017-87528-R AEI/FEDER EU) and a GRUPIN grant IDI/2021/000075 (Asturias Government).

Peer reviewed