Epidemiological study on foot-and-mouth disease in small ruminants: sero-prevalence and risk factor assessment in Kenya

Abstract

Foot-and-mouth disease (FMD) is endemic in Kenya affecting cloven-hoofed ruminants. The epidemiology of the disease in small ruminants (SR) is not documented. We carried out a cross-sectional study, the first in Kenya, to estimate the sero-prevalence of FMD in SR and the associated risk factors nationally. Selection of animals to be sampled used a multistage cluster sampling approach. Serum samples totaling 7564 were screened for FMD antibodies of Non-Structural-Proteins using ID Screen(R) NSP Competition ELISA kit. Data were analysed using Statistical Package for Social Studies Version 20. To identify the risk factors, chi-square and logistic regression analyses were used. The country animal level sero-prevalence was 23.3% (95% CI: 22.3-24.3%) while herd level sero-prevalence was 77.6% (95% CI: 73.9-80.9%). Sero-positivity was significantly higher in the pastoral zone (31.5%) than in the sedentary zone at 14.5% ({chi}2 =303.2, p<0.05). In the most parsimonious backward fitting logistic multivariable regression, the only risk factors that were significantly positively associated with FMD sero-positivity in SR were multipurpose (OR=1.150; p=0.034) and dairy production types (OR=2.029; p=0.003). Those that were significantly negatively associated with FMD sero-positivity were male sex (OR=0.856; p=0.026), young age (OR=0.601; p=0.037), sedentary production zone (OR=0.471; p<0.001), bringing in of SR (OR=0.838; p=0.004), purchase of SR from market/middlemen (OR=0.877; p=0.049), no interaction with wildlife (OR=0.657; p<0.001), mixed production type (OR=0.701; p=0.016), enclosure of SR day and night (OR=0.515; p=0.001), migratory grazing system (OR=0.807; p=0.047), on-farm watering system (OR=0.724; p=0.002), male-from-another-farm (OR=0.723; p=0.030) and artificial insemination (OR=0.357; p=0.008) breeding methods. This study showed that there is widespread undetected virus circulation in SR indicated by ubiquitous spatial distribution of significant FMD sero-positivity in the country. The risk factors were mainly husbandry related. Strengthening of risk-based FMD surveillance in carrier SR which pose potential risk of virus transmission to other susceptible species is recommended. Adjustment of husbandry practices to control FMD in SR and in-contact species is suggested. Cross-transmission and more risk factors need to be researched.