Sero-prevalence and risk factors of infectious bovine rhinotracheitis virus (type 1) in Meru County, Kenya

Abstract

The aim of the study was to determine the antibody sero-prevalence of Bovine Herpesvirus-1 which cause Infectious Bovine Rhinotracheitis (IBR) and to identify risk factors associated with BHV-1 antibody seropositivity among smallholder dairy farms in Meru County, Kenya. A cross-sectional study was conducted in the Naari area of Meru County, Kenya between September-October 2016 and March-April 2017. The 149 farmers were randomly selected from members of the Naari Dairy Farmers Cooperative Society who were actively delivering milk to the society at the time of the study. Serum samples were obtained from 403 female dairy cattle. Farm level management and animal factors were collected through direct interviews with the owner or someone who was knowledgeable about the animals. All serum samples were processed with an indirect enzyme-linked immunosorbent assay (gB ELISA) to determine the presence of antibodies to BHV-1. The overall farm-level and animal-level sero-prevalences of BHV-1 antibodies were 30.9 % (95 % CI: 23.6%-39.0%) and 17.4 % (95 % CI: 13.8%-21.4%), respectively. In the final multivariable analysis, the factors significantly associated with BHV-1 antibodies included; age of the dairy cattle (OR = 1.200, p = 0.001), age of the principal female farmers (OR = 0.182, p = 0.001) and rearing goats in the farm (OR = 26.77, p = 0.000). There was a significant interaction between rearing goats on the farm and age of the dairy cattle (p < 0.010); younger cattle seemed to have been exposed to BHV or a cross-reacting caprine herpesvirus when goats were on the farm. The results showed that BHV-1 was circulating among the cattle population in the Naari area of Meru County. Given that there is not BHV-1 vaccination use in this study population, training on the importance of biosecurity and vaccination for BHV-1 are recommended to reduce the transmission and impacts of BHV-1.

Keywords: Bovine Herpesvirus type 1 (BHV-1); Dairy cattle; Infectious Bovine Rhinotracheitis (IBR); Risk factors; Sero-prevalence.