Seropositivity and associated intrinsic and extrinsic factors for Rift Valley fever virus occurrence in pastoral herds of Nigeria: A cross sectional survey
Background: Rift Valley fever (RVF) is a vector-borne emerging zoonotic disease of animals and humans, characterized by major socioeconomic losses to livestock farmers, with potential global public health threat. The study determined RVFV seroprevalence in cattle, as well as assessed pastoralists' existing knowledge about the diseases, and factors that influence RVFV occurrence in pastoral cattle herds of Nigeria. Methods: A cross-sectional study was conducted in pastoral herds of North-central
... ds of North-central Nigeria from 2017 to 2018. Data collections were carried out using serology and questionnaire tools. Descriptive statistics, using frequencies and proportions, were used to analyze data obtained from the survey. Categorical variables were presented as proportions and their associations determined by Chi-square tests. Associations of risk factors were analyzed by univariable and multivariable logistic regressions analyses at 95% confidence level. Results: The overall IgM seropositivity of RVFV in pastoral cattle herds of North-central Nigeria was 5.6%. This was higher in nomadic cattle (7.4%) than agro-pastoral animals (3.8%). All animal demographic characteristics of age, sex and breeds were not significantly (p>0.05) associated with RVFV occurrence in pastoral herds. All the 403 pastoralists selected participated in the study, with the majorities of respondents being male, married and having formal education. Majority of the pastoralists had low knowledge levels about zoonotic RVFV infection. However, all identified socio-ecological factors significantly (p<0.05) influenced RVFV occurrence in pastoral cattle herds. Mosquitoes availability in cattle herds environment (OR=7.81; 95% CI: 4.85, 12.37), presence of rivers and streams at grazing fields (OR=10.80; 95% CI: 6.77, 17.34), high rainfall (OR=4.30; 95% CI: 2.74, 6.59), irrigated rice fields (OR=5.14; 95% CI: 3.21, 7.79) , bushy vegetation (OR=6.11; 95% CI: 3.96, 9.43), animal movement (OR=2.2; 95% CI: 1.45, 3.25), and seasons (OR=2.34; 95% CI: 1.55, 3.51) were more likely to influence RVFV occurrence in pastoral cattle herds. Conclusions: The results of this study illustrated recent circulation of RVFV in pastoral cattle herds of Nigeria and needs urgent interventions. Low levels of knowledge about RVF were also highlighted amongst surveyed pastoralists and identified socio-ecological factors significantly influenced RVFV occurrence in herds. Adequate knowledge about RVF epidemiology will assure food security and public health.