Systematic examination of the cardiopulmonary, urogenital, muscular and gastrointestinal parasites of the Eurasian otters (Lutra lutra) in Denmark, a protected species recovering from a dramatic decline

The Eurasian otter (Lutra lutra) is a protected species in Denmark and at present, the population is recovering due to conservation efforts. The Danish otters are mainly found in the continental part of Denmark (Jutland), but establishment in the main islands (Fyn and Zealand) has been observed. While there is a lack of systematic studies on the parasite fauna of otters in Denmark, this study aims to screen otters for their parasite fauna, especially those of zoonotic and/or veterinary importance. Thirty-three otter carcasses, road-killed (n = 30), found dead (n = 2) and shot (n = 1), were collected between June 2013 and May 2014 and examined for cardiopulmonary, urogenital, gastrointestinal, and muscle helminths by post mortem examination. Faecal samples were analysed by modified concentration McMaster technique and direct immunofluorescence test for Giardia and Cryptosporidium. At least one parasite was found in 75.8% of animals. The parasite fauna included 13 species, consisting of five nematodes: Molineus patens (30.3%), Aonchotheca putorii (27.3%), Strongyloides sp. (24.2%), Physaloptera sp. (12.1%), Eucoleus aerophilus (10.0%); one cestode: Schistocephalus solidius (6.1%); four trematodes: Metorchis bilis (33.3%), Isthimiophora melis (15.2%), Cryptocotyle sp. (3.0%), Plagiorchis sp. (3.0%); one acanthocephalan: Acanthocephalus ranae (18.2%); and two protozoans: Giardia spp. (3.1%), and Eimeria spp. (3.1%). The study showed that otters carry parasites of zoonotic and veterinary importance. Many of these parasites can also infect native carnivores and birds, and the distribution of these parasites may be affected if the otter population continue to increase in Denmark. •Systematic examination for internal parasites of Danish otters was performed.•75.8% of 33 otters harboured at least one parasite species.•33.3% of 30 otters were infected with the zoonotic trematode Metorchis bilis.