Prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria

Abstract

Using a cross-sectional survey, we determined the prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria. Antibodies to Brucella species in serum samples were tested using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (cELISA); for milk, the milk ring test (MRT) and indirect-ELISA (i-ELISA) were used. Questionnaire was administered to cattle herdsmen to determine factors predisposing the animals to bovine brucellosis. Data were analyzed using STATA 12. From 513 serum and 635 milk samples tested among 120 herds, overall animal-level prevalence of 10.1% (95% CI 7.5-12.7%) and 20.2% (95% CI 17.1-23.3%) were recorded by RBT and MRT, respectively; while 9.4% (95% CI 6.9-11.9%) and 17.8% (95% CI 14.8-20.8%) were obtained using cELISA and i-ELISA, respectively. In all, from the 120 herds tested, 29.2% and 43.3% were positive by RBT and MRT, respectively. Multivariable logistic regression revealed that herd location (OR = 8.12, 95% CI 1.68-38.90) and improper disposal of placenta/fetus (OR = 17.33, 95% CI 4.81-62.33) were predictors for a seropositive herd using RBT; while herd location (OR = 5.13, 95% CI 1.27-20.28), large herd size (OR = 2.62, 95% CI 1.15-5.85), and occurrence of abortion for a year or more (OR = 4.62, 95% CI 1.53-13.71) were predictors of seropositivity to antibodies to Brucella spp. using MRT. We found high prevalence of brucellosis in cattle herds under extensive management system in southwestern Nigeria. Urgent and coordinated control strategies are required to mitigate this problem.

Seroprevalence and associated factors of brucellosis and Q-fever in cattle from Ibarapa area, Oyo state, south-western Nigeria

“…The highest seroprevalence was observed in herds with animals >50 (30.77%) than those with smaller sized herds. This is consistent with other findings in Nigeria [ 3 , 13 , 32 ]. This could be due to an increase in exposure to Brucella spp .…”

“…Furthermore, this could be linked to lack of awareness on the mode of transmission of the disease among the herdsmen [ 19 ], which in turn leads to infected animals with signs of the disease being retained within the herds [ 3 ]. The brucellosis seroprevalence was however lower than the reports of 18.5% in Kaduna State, Nigeria [ 4 ] and 12.91% in Kenya [ 20 ] but higher than reports of 10.1% in some other settings in Southwestern Nigeria [ 13 ]. The nomadic system practised among the Fulani herdsmen in Nigeria has been identified as a major risk factor for Brucella infection [ 3 ].…”

“…A plausible reason for this is the prolonged exposure of animals to Brucella spp . in an infected herd [ 13 ]. Notably, brucellosis can occur in all the age groups of cattle but is commonly known to persist in sexually mature animals [ 30 ].…”

“…Of the three LGAs of Ibarapa, two were selected (Ibarapa East and Central) from which one town each (Eruwa and Igbo-Ora) were selected and a total of 16 cattle herds sampled from both towns. The required number of animals to be sampled was calculated using an expected prevalence (Pexp) of 10.1% [ 13 ] for brucellosis and 6.2% [ 4 ] for Q-fever, a confidence interval (CI) of 95% and a desired absolute precision of 5%. The sample size was calculated using:…”

Seroprevalence of Bovine Brucellosis in Selected Districts of Zambia

“…Most developed countries have managed to eradicate bovine brucellosis [12]. However, it is still endemic in most Sub Saharan African countries at varying seroprevalence [13][14][15][16][17][18]. In Southern Africa, the accurate brucellosis picture is not clearly known because most reports are based on nonrepresentative laboratory results.…”