Epidemiological survey of brucellosis in sheep and goats in selected pastoral and agro-pastoral lowlands of Ethiopia.

Abstract

An epidemiological survey was conducted in pastoral regions of Ethiopia to investigate the distribution of brucellosis in sheep and goats. Between November 2004 and December 2007, a total of 6,201 serum samples were collected from 67 randomly selected peasant associations, 25 districts and eight pastoral zones of Ethiopia. The Rose Bengal plate test (RBPT) and complement fixation test were used in series. Samples for bacteriology were collected from three export abattoirs, where 285 goats were randomly selected and tested by RBPTthree days before slaughter. Tissue samples were collected from 14 strongly positive goats and cultured in dextrose agar and Brucella agar base. To confirm and subtype the isolates, staining, biochemical tests and polymerase chain reaction were used. The overall standardised seroprevalence of brucellosis was 1.9%, ranging from 0.07% in Jijiga zone to 3.3% in Borena zone. There was statistically significant variation among the studied regions, zones, districts and peasant associations (p < 0.05). Male goats and sheep were twice as likely to test positive as females (relative risk [RRJ: 2.04; 95% confidence interval [CI]:1.7-3.4; x2 = 21.05, p < 0.05). Adults (older than 1.5 years) were three times more likely to test positive than younger animals (RR: 2.76; 95% CI: 1.14-6.73; chi2 = 5.18, p < 0.05). Goats were around four times more likely to be infected than sheep (RR: 3.8; 95% CI: 2.4-6.1; chi2 = 36.99, p < 0.05). Brucella melitensis was isolated from 2 of the 14 samples analysed. The widespread distribution of brucellosis in goats and sheep in these areas justifies the use of control measures to minimise the economic losses and public health hazards.