Sheep and goat brucellosis in Borno and Yobe states of arid northeastern Nigeria

Abstract

A serological survey of small ruminant brucellosis was conducted in 210 sheep consisting of 98 Yankassa, 51 Uda and 61 Balami breeds and 201 goats consisting of 90 Borno White, 64 Sokoto Red and 47 crossbred breeds from various nomadic and sedentary flocks in Borno and Yobe States in the arid zone of northeastern Nigeria. Ten (4.8%) of 210 sheep, and 12 (6.0%) of 201 goats tested sero-positive using the Rose Bengal Plate Test (RBPT). Results using the Serum Tube Agglutination Test (SAT) which was used to complement the RBPT were generally lower but were comparable with those of the RBPT. Infection rates were generally higher in goats (6.0%) than in sheep (4.8%), but there was no difference between the species with the RBPT, nor in rates (3.3% in sheep and 4.5% in goats) with the SAT ( P = 0.26). There was no significant difference in infection rates amongst different breeds within each species. Breed susceptibility to infection was non-discriminatory. Infection rates were higher in females than males with RBPT in sheep ( ∗P = 0.012 ) and goats ( ∗P = 0.026 ). The risk of acquiring brucellar infection, the relative risk ( R e) was 4.6 times higher in ewes than in rams with RBPT, and 3.1 times higher with SAT. In goats, risk of acquiring infection was 29.8 times higher in females than in males by RBPT and 22.2 times higher by SAT. There was, however, no significant epidemiological sex-linked association in infection rates. Zoonotic and economic implications accruing from small ruminant brucellosis in the two important livestock producing states of Nigeria are far-reaching, with an estimated annual loss in excess of about US$ 3.2 million at the current level of prevalence.