Seroprevalence and spatial distribution of livestock brucellosis using three serological tests in Kajiado County,...

Brucellosis is a serious zoonotic infection with a global socioeconomic impact on both the livestock industry and human health. In Kenya, brucellosis is endemic but there is limited information on the true burden of the disease due to weak or peace-meal surveillance. The true burden and spread of animal brucellosis in Kajiado County is not known.

The aim of the study was to determine the current seroprevalence and spatial distribution of livestock brucellosis in Kajiado County and also to compare the three serological tests, namely; Rose Bengal plate test (RBPT), indirect enzyme-linked immunosorbent assay (i-ELISA), and competitive ELISA (c-ELISA) in the detection of seropositive animals.

A cross-sectional study was undertaken in 5 sub-counties and 13 wards, where a total of 782 serum samples from unvaccinated bovine (n = 278; 34 herds), ovine (n = 256; 25 flocks), and caprine (n = 248; 28 flocks), were screened for anti-Brucella antibodies using RBPT, i-ELISA, and c-ELISA tests, in parallel.

Overall animal seroprevalence was 6.91% (54/782); while that for bovine, ovine, and caprine was 18.35% (51/278), 0.78% (2/256), and 0.4% (1/248), respectively. Bovine seroprevalence was 2.2% (6/278), 14.4% (40/278), and 4.7% (13/278) in RBPT, i-ELISA, and c-ELISA tests, respectively; while ovine 0.78% (2/256) and caprine 0.4% (1/248) were positive only in c-ELISA. Bovine herd seropositivity was 67.65% (23/34), whereas ovine and caprine flock seropositivities were 8% (2/25) and 3.6% (1/28), respectively.

The findings indicate a moderate seroprevalence of brucellosis in bovine, while that of ovine and caprine was low in Kajiado County. Indirect ELISA was found superior to both c-ELISA and RBPT in detecting bovine seropositive animals, while c-ELISA was superior to both RBPT and i-ELISA in detecting seropositive ovines and caprines. These results will contribute to baseline data for further study of Brucella infection and a starting point for the formulation of a strategy for the control of brucellosis in Kajiado County.