Abstract:
BACKGROUND: This study was carried out to investigate the status of brucellosis in cattle under various management
systems in Adamawa, Kaduna and Kano states, northern Nigeria. Using multi-stage sampling, serum samples of
4,745 cattle from 271 herds were tested using the Rose-Bengal plate-agglutination test (RBPT) and positives were
confirmed using a competitive enzyme-linked immunosorbent assay (c-ELISA).
RESULTS: Prevalence estimates were calculated by adjusting for sampling weights and where possible for test
sensitivity and specificity. Thirty-seven percent of all animals were RBPT positive, and after confirmation with c-ELISA
the overall animal-level prevalence, adjusted for sampling weights, was 26.3% (95% CI, 22.1%-31.0%). Of the herds
sampled, 210 (77.5%; 95% CI, 68.6%-84.5%) had at least one animal positive to both tests; this did not differ
significantly between states (P = 0.538). Mean within-herd seroprevalence in positive herds was 30.2% (95% CI,
25.3%-35.1%) and ranged from 3.1% to 85.7%. Overall animal-level seroprevalences of 29.2% (95% CI, 22.5%-36.9%)
n = 1,827, 23.3% (95% CI, 18.9%-28.3%) n = 1,870 and 26.7% (95% CI, 18.8%-36.7%) n = 1,048 were observed in
Adamawa, Kaduna and Kano states, respectively (P = 0.496). A significantly higher seroprevalence was found in
males (38.2%; 95% CI, 31.7%-45.2%) than in females (24.7%; 95% CI, 20.4%-29.5%) (P < 0.001) and in non-pregnant
females (27.8%; 95% CI, 22.9%-33.5%) than in pregnant females (17.2%; 95% CI, 13.6%-21.5%) (P < 0.001).
Seroprevalence increased with increasing age (P < 0.001), from 13.5% (95% CI, 8.9%-19.9%) in cattle <4 years to
35.0% (95% CI, 28.5%-42.3%) in cattle >7 years. Seroprevalence also varied between management systems
(P < 0.001): pastoral systems 45.1% (95% CI, 38.6%-51.9%), zero-grazing systems 23.8% (95% CI, 6.8%-59.2%),
agro-pastoral systems 22.0% (95% CI, 17.3%-27.8%), and commercial farms 15.9% (95% CI, 9.5%-25.5%).
Seroprevalence did not differ significantly between breeds or lactation status.
CONCLUSION: This is the first large study to assess the prevalence of bovine brucellosis over a wide geographic area
of northern Nigeria, in a variety of management systems and using accurate tests. The seroprevalence of brucellosis
was high, and higher than results of previous studies in northern Nigeria. The pastoral management systems of the
traditional Fulanis may be encouraging the dissemination of the disease. Public enlightenment of the farmers about
the disease, vaccination and appropriate national control measures are recommended.
