EPIZOOTIC SITUATION OF HEMOPARASITIC DISEASES OF FARM ANIMALS IN IRKUTSK REGION

Abstract

Background. Cattle anaplasmosis and babesiosis and theileriosis of horses are a group of natural focal vector-borne diseases that cause significant economic damage to livestock and horse breeding around the world. On the territory of the Baikal region these diseases and their pathogens remain little explored. Purpose – to study the epizootic situation of blood-parasitic diseases of farm animals in the Irkutsk region, to establish the species affiliation of the identified pathogens and their genetic diversity. Materials and methods. For the presence of Babesia spp./Theileria spp. and Anaplasma spp. has been researched659 horse blood samples, 579 sheep blood samples, 25 goat blood samples and 647 cattle blood samples. For the detection of babesia and theileria, nested two-round PCR with primers from the 18S rRNA gene region was used, and for the detection of anaplasma DNA with primers from the 16S rRNA gene region. For study the genetic diversity of the identified pathogens, selective sequencing of samples was carried out with subsequent phylogenetic analysis. Results. The DNA of Anaplasma spp. was detected in blood samples of small ruminants from 12 districts of the region. The infection rate of sheep and goats was 68.7±1.9% and 68%±9.3%, respectively. Nucleotide sequences of the 16S rRNA gene fragment were determined in 68 A. ovis samples from the blood of sheep and goats. The researched sequences were conservative for the studied gene and differed from each other in two heterozygous sites of the gene(T/C and G/A nucleotide substitutions).They corresponded to the sequences of the prototype strain Haibei (CP015994), as well as to the A. ovis sequences previously found in the blood of sheep from Altai (Russia) and Mongolia, deer and D. niveus and D. nuttalli ticks from China. DNA of Babesia spp./Theileria spp. found in blood samples of horses from 13 districts of the region. The average infection of horses was 64.2%±1.9%. Two etiological agents of equine piroplasmosis were found in the blood of the examined horses: T. equi (genetic groups A and E) and B. caballi. Definite sequences of the B. caballi 18S rRNA gene (700–1146 bp) were identical to each other and differed by at least ten substitutions and one deletion from the sequences available in the GenBank database. However, the greatest similarity was observed with B. caballi sequences found in the blood of a horse from Brazil (KY952238), ticks from Kazakhstan (MN907451) and China (MN173021). The results indicate that DNA of Anaplasma and Babesia in the blood of cattle have not been identified. Conclusion: The data received evidence a wide distribution of foci of small cattle anaplasmosis and piroplasmosis of horses in the Irkutsk region and the need to continue monitoring their epizootic condition.

Keywords

• anaplasmosis
• babesiosis
• theileriosis
• piroplasmosis
• hemoparasitic diseases
• epizootic situation