Sero-prevalence and Risk Factors of Infectious Bovine Rhinotracheitis in the Smallholder Dairy Farms of Naari Sub-location of Meru County, Kenya

The aim of the study was to analyze the sero-prevalence and risk factors of the Infectious Bovine Rhinotracheitis disease among organized small holder dairy farms in the Naari area of Meru County, Kenya. A cross-sectional study was conducted in the Naari area of Meru County, Kenya between June-July 2018 and March-April 2018. 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 results revealed that the sero-prevalence of IBR among the smallholder dairy cows’ population in part of the large Meru County was 17.37% (95% CI: 13.80% to 21.43%). Among the categorical predictor, the sero-prevalence of the breeds of the dairy cows were Ayrshire (20.0%), Friesian (16.3%), Guernsey (17.9%) and Zebu (16.1%). The proportions positive for BoHV -1 among parity of the dairy cows were Heifer (parity 0) (15.0%), Primi-para (parity 1) (12.8%) and Multi-para (parity 2 – 8) (19.8%). The cow-heifer category was cow (18.7%) and heifer (12.2%). The feeding systems employed in the production of dairy cows were zero – grazing (17.5%), semi zero – grazing (18.9%) and grazing (12.1%). The study found out that the IBR infection was positively associated with the following factors; age of the dairy cattle (OR = 1.112, 95% CI = 1.012 – 1.222, P = 0.027), cows that were borrowed into farms (OR = 4.893, 95% CI, = 1.328 – 16.03,1 P = 0.017), rearing goats in the farms (OR, 1.438, 95% CI, 1.109 – 1.863, P = 0.006), cows that were given out of the farms (OR, = 2.486 95% CI, = 0.697 – 8.859 p = 0.014), Showed BVD signs OR = 1.243 95% CI, = 0.635 – 2.430, p = 0.526) and cows that had antibodies against Bovine Viral Diarrhea Virus (OR, = 2.262 95% CI, = 1.129 – 4.533, P = 0.021). The final multivariate analysis of individual level factors that were associated with those that tested positive to BoHV – 1 antibodies included; rearing goats on the farm (OR = 4.636, 95% CI = 2.053 – 10.467, P = 0.001), age of the dairy cattle, (OR = 1.113, 95%CI = 1.017 – 1.217, P = 0.020) and age of the female principal farmers (OR = 0.174, 95% CI = 0.082 – 0370, P = 0.001). The study concluded that BoHV – 1 is naturally circulating among cattle population in Meru County, Kenya. There was a positive association between age of the dairy cattle, age of the principal female farmers and rearing of goats in the farm together with cattle, and BoHV – 1 sero-prevalence observed in the study. Thus, cattle population may be protected via punctual vaccination while considering the differentiation of infected from vaccinated cattle. Furthermore, there is need for a study to be carried out to identify long term effects of BoHV – 1 and access the potential ability of the viral cross infection with other four related Alpha-herpesviruses with BoHV – 1 among the cattle population. Keywords: Infectious Bovine Rhinotracheitis (IBR), Bovine Herpesvirus type 1 (BoHV – 1) Cattle, Sero-Prevalence and risk factors.