Endoparasites of the European beaver (Castor fiber L. 1758) in north-eastern Poland

Abstract

Parasitological examination after necropsies of 48 European beavers from Podlaskie and Warmisko-Mazurskie provinces were performed between April 2011 and November 2012. All helminthes were isolated from the contents of the gastro-intestinal tract and their species were determined. In addition, blood samples and faeces were examined. All beavers were infected with six species of parasites. Stichorchis subtriqetrus trematodes were found in 93.7% of animals. They were localized mainly in the caecum, less in the colon, and single juvenile parasites were found in the small intestine. The intensity of infection ranged from two to 893 parasites. Travassosius rufus nematodes (10-4336 specimens) were present in the stomach of 68.7% of the beavers. In the small intestine of four (8.3%) beavers, two-six specimens of Psilotrema castoris were found. This is the first record of this species in Poland and the third of its discovery in the world. Furthermore, in the small intestine of one beaver, two Trichostrongylus capricola nematodes were detected. In the liver of one beaver, pathological changes caused by hydatid cestode Echinococus granulosus occurred. Inflammatory changes of the gastric mucosa caused by Travassosius rufus and of caecum caused by Stichorchis subtriquertus, were observed. Coproscopy was performed with the use of Baermann, flotation, and decantation methods. All results of Baermann method were negative. Examinations with flotation and decantation methods confirmed necropsy findings. Using the flotation method, single oocysts of Eimeria sprehni in one beaver were detected. A blood test conducted by Kingston and Morton method did not reveal the presence of protozoa or microfilariae.

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

“…Also in Poland, the intensity was higher among young beavers [24]. For T. rufus, the intensity (and the prevalence) was higher in the older beavers [24]. These findings might have a bearing on Swedish beavers.…”

“…We conclude that all populations originating from Norway have the same restricted helminth fauna. In Poland, where Norwegian beavers were not introduced [73], two studies found four species of helminths, including T. rufus and S. subtriquetrus [23,24]. In these studies, 43 individuals [23] and 48 individuals [24] were sampled, respectively.…”

“…In North America, several surveys cover both the helminth and arthropod parasites of C. canadensis [12][13][14][15][16][17][18]. In Europe also, a number of studies of the parasites of C. fiber are reported [7,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. In total, 33 helminth species have been found in C. fiber [7,36,37].…”

“…Russian studies indicate that the intensity of S. subtriquetrus is highest in beavers at the age of 7-10 months, and then decreases with ageing, but with a seasonal peak in the autumn [37]. Also in Poland, the intensity was higher among young beavers [24]. For T. rufus, the intensity (and the prevalence) was higher in the older beavers [24].…”

Potential role of beavers (Castor fiber) in contamination of water in the Masurian Lake District (north-eastern Poland) with protozoan parasites Cryptosporidium spp. and Giardia duodenalis

“…Currently, the estimated beaver population in Poland is about 50 000 individuals, localised mainly in the north-eastern part of the country (6). Only a small number of (oo)cysts are sufficient to cause human outbreaks.…”