On parasite fauna of the European beaver

The purpose of the research is identification of the current parasitological situation for Eurasian beavers inhabiting the Central Russia.Materials and methods. The work was carried out on hunting farms and in specially protected areas of the Central Russia. Potentially infective material was collected, recorded and preserved from animals during 2015–2021. The age of the animals was determined by their weight and physiological state of the rodents’ teeth and internal organs, and the sex was determined by their genitals. The animals were examined according to the method of complete and partial helminthological dissection per Skryabin.Results and discussion. A total of 41 animals were examined. Three forms of parasitism on animals were identified in natural habitat, namely, the trematode Stichorchis subtriquetrus, the nematode Travassosius rufus, and the ectoparasite Platypsyllus castoris. The stichorchosis causative agent localized in the animal’s large intestine was diagnosed in 35 rodents (85.4%). The helminth infection was 96% in the Eurasian beaver and 68.7% in the Canadian beaver. The nematode infection in stomach was detected in 31 animals (75.6%). The infection by T. rufus was 88% in the Eurasian beaver, and 56.3% in the Canadian beaver. The infected animals were delivered from the Vladimir, Moscow, Ryazan, Tula and Yaroslavl Regions. The beaver beetle P. castoris was found in 6 animals (14.6%). The infection rate was 8% in the Eurasian beaver, and 25% in the Canadian beaver. Animals with wingless arthropods have been identified in the Moscow and Ryazan Regions.

Parasitic fauna of Eurasian beavers (Castor fiber) in Sweden (1997–1998)

Background The parasitic fauna of beavers (Castor fiber and C. canadensis) has been well studied in many parts of their respective areas of distribution. In Scandinavia there have, however, been limited investigations conducted on the parasites of beavers in recent times. The present study is the first quantitative survey of parasites on beavers living in Sweden and elsewhere in Scandinavia. We investigated the parasitic fauna of the Eurasian beaver (C. fiber) in a North–South gradient in Sweden. The aim of the study was to investigate parasite distribution and prevalence in particular, related to average yearly air temperature and different age groups of beavers. A total of 30 beavers were sampled at eight localities, spanning a 720 km North–South gradient during the springs of 1997 and 1998. Results Five parasite taxa were identified. Four of these were present in all of the examined beavers, Stichorchis subtriquetrus (trematode), Travassosius rufus (nematode), Platypsyllus castoris (coleopteran), and Schizocarpus spp. (arachnid). A higher number of new infections of S. subtriquetrus, and more adults of T. rufus, were seen in beavers in southern Sweden where temperatures are higher. One-year old beavers had a higher infestation of S. subtriquetrus, but not of T. rufus, than older individuals. Conclusions The parasite fauna of Swedish beavers mirrored the impoverished parasite fauna of the original Norwegian population, and the high prevalence of parasites could be due to low major histocompatibility complex (MHC) polymorphism. Young beavers had a higher load of trematodes, probably depending on behavioural and ecological factors. Warmer temperatures in southern localities likely contributed to increased endoparasite loads.

Stichorchis subtriquetrus in two beavers (Castor fiber) from Slovenia

Intestines of two beavers (Castor fiber), one killed by a car accident and one drowned were examined for parasites. Examination revealed the presence of 1 and 14 adult trematodes, Stichorchis subtriquetrus in the caecum and colon, respectively. The flotation method revealed no ova from faecal material. The European beaver was present in the territory of Slovenia until the beginning of the 18th century. Recently, in 1998, the species reappeared in southeast of Slovenia as a result of the reintroduction of European beaver in Croatia. This is the first report of veterinary examination of beaver and the first evidence of S. subtriquetrus in Slovenia.

Reintroduction of the European beaver (Castor fiber L.) into Serbia and return of its parasite: The case of Stichorchis subtriquetrus

After becoming extinct in the second half of the 20th century, the European beaver (Castor fiber L., 1758) was successfully reintroduced from Bavaria into Serbia during 2004-2005. In the necropsy of an adult female beaver (found dead in December of 2007), we discovered some parasites identified as Stichorchis subtriquetrus in the colon and peritoneal area. This is the first occurrence of the given specific parasite of beavers in Serbia. Decoding of a subcutaneous implanted microchip has confirmed that our specimen was one of the released beavers. We therefore conclude that the parasite in question was reintroduced into Serbia with the beavers originating from Bavaria.

ON THE INCIDENCE OF GASTROINTESTINAL PARASITES IN NOVA SCOTIA BEAVER

Complete gastrointestinal tracts from 132 Nova Scotia beaver (Castor canadensis) and partial tracts from 14 others were examined for the presence of parasites. The nematode, Travassosius americanus, and the trematodes, Stichorchis subtriquetrus, Stephanoproraoides lawi, and Echinostomum armigerum, were the only parasites recovered. T. americanus and S. subtriquetrus were recovered from a high proportion of the beaver, and E. armigerum and S. lawi were recovered in one and three beaver respectively.