Occurrence and epidemiology of bovine coronavirus in cattle in Kazakhstan.

Bovine coronavirus (BCoV) causes gastrointestinal and respiratory diseases in cattle, but its prevalence in Kazakhstan remains unknown. This nationwide cross-sectional study aimed to assess BCoV prevalence in cattle and to investigate its epidemiological characteristics. Between April and August 2024, serum, nasal and rectal swab samples were collected from 2237 clinically healthy cattle across 390 farms in 17 oblasts of Kazakhstan. None of the farm owners reported vaccinating against BCoV. Serum samples were tested for BCoV-specific antibodies using a commercially available ELISA, while nested RT-PCR assays were performed on pooled nasal and rectal swabs to detect BCoV RNA. Sequencing and phylogenetic analysis were performed following RT-PCR testing. A univariate GEE model was used to assess the risk factors and a multivariate model was employed to refine the discovered associations. The animal-level seroprevalence of BCoV was 88.2 % (95 % CI: 84.3 %-92.0 %), while the herd-level seroprevalence was 89.6 % (95 % CI: 85.4 %-92.9 %). The eastern region of Kazakhstan had the lowest seroprevalence compared to other regions. Seropositivity was not associated with age, sex or breed, but correlated with the proportion of cattle in backyards, cattle density and farm size. BCoV shedding was detected in 2.4 % (95 % CI: 1.4 5 % - 3.4 %) of sampled animals and in 7.8 % (95 %CI: 5.3 % - 11.0 %) of cattle operations across 12 oblasts. Phylogenetic analysis of the complete hemagglutinin/esterase and spike genes revealed that the Kazakhstani BCoV strains belonged to the GIIa group. This first report on BCoV in Kazakhstan confirms its endemic presence, highlighting the need for a national control program.