Epizootic monitoring of protozoozes in the fur farms of the Kaliningrad region (2018-2020)

Parasitic diseases are widespread in fur-bearing animals, especially in minks. Coccidiidoses occupy a special place among invasive diseases, as they often occur without any symptoms and in some cases are not timely diagnosed. Despite the mild clinical manifestation of invasion, it causes serious damage to animal health and significant economic damage to fur-bearing animal farms. After analyzing the literature data, it became clear that the distribution of eimerioses of fur-bearing animals in the Kaliningrad region has not been studied well enough. In particular, there is no information about the prevalence rates, invasion intensity, and age dynamics of the mink eimeriosis in the fur farms of the region. The purpose of this work was to study the epizootic situation on mink ( Mustela vison , Linnaeus, 1761, Neovison vison Schreber, 1777) coccidiidoses in fur-bearing animal farms in the Kaliningrad region. Investigations were performed in three fur-bearing animal farms of the Kaliningrad region. The species composition of protozoa in minks was determined by the morphological features of coccidia and by deep sequencing of the 18S rDNA V4 region. OTUs (operational taxonomic units) revealed by the bioinformatic analysis were used to establish the taxonomic affiliation of pathogens which confirmed the results of light microscopy. In analyzing the obtained results and choosing research methods, the age, sex of the animals, as well as housing and feeding conditions were taken into account. Young minks of 5-6 months and adult livestock, 1-2 year-old females and males, were surveyed. In total, 561 animals were examined in three farms, including farm 1 - 273 minks (198 young animals, 75 adults - 33 males and 42 females); farm 2 - 160 minks (68 young animals, 92 adults - 44 males and 48 females), and farm 3 - 128 minks (28 young animals, 100 adults - 44 males and 56 females). In all the farms surveyed, we found the protozoan of the Eimeriidae family. The greatest prevalence rates (56 %) and the widest variety of coccidia species occurred in the animals of farm 1 under the invasion of two eimeria, Eimeria vison and E. furonis , and two isospores, Isospora laidlawi and I. eversmanni (the I. eversmanni we have earlier identified in minks in the Kaliningrad region for the first time). In all fur farms in the Kaliningrad region, eimerioses more often occur as mono invasions. In mixed invasions, 68.55 % were two-parasite invasions, 23.67 % were three-parasite invasions. Young minks are more susceptible to eimeriidoses than adults. In the animals of the current year of birth, E. vison (18.36 %), I. laidlawi (16.32 %), and E. vison + I. laidlawi (11.90 %) prevailed.