Abstract
Aims
The study aimed to determine the serological and molecular prevalence of livestock brucellosis in Narok County, Kenya.
Methods
An extensive cross-sectional study covering 5 sub-counties and 13 wards in Narok County was conducted between December 2019 and December 2022. A total of 762 serum samples from bovines (254), ovines (250), and caprines (258) were tested for Brucella antibodies using serological tests (RBPT, i-ELISA, and c-ELISA), and 184 seropositive and seronegative serum samples were analyzed for Brucella spp. DNA using conventional PCR
Results
The study revealed variable brucellosis detection rates across species and diagnostic tests. RBPT detected brucellosis in 21.3% bovines, 0% ovines, and 0.4% caprines, with an overall positivity rate of 7.23%. In contrast, c-ELISA detected 28.35% bovines, 2.4% ovines, and 0.4% caprines as positive, resulting in a total positivity rate of 10.37%; and i-ELISA detected 25.6% positive bovines, with no positive cases in ovines or caprines, leading to an overall rate of 8.53%. Combining all three tests (RBPT, i-ELISA, and c-ELISA) resulted in a maximum positivity rate of 11.42% in bovines. Overall seropositivity was 45.3% in bovines, 2.4% in ovines, and 0.78% in caprines, averaging 16.14% across all species. Among the tests, c-ELISA had the highest accuracy. Herd-level seropositivity was highest in bovines (90.3%), particularly in herds with a history of abortion (53.85%). The highest prevalence in sub-counties was in Narok South (58.3%). Molecular testing showed a 1.63% prevalence, with Brucella abortus detected in two seropositive bovines and one seronegative caprine.
Conclusions
The study revealed high brucellosis rates in bovines, with lower rates in ovines and caprines. It underscored the necessity of using multiple diagnostic tests to avoid misestimation of prevalence, as relying on a single test can lead to inaccuracies. The results imply that the actual prevalence might be lower than initially reported and emphasize the need for targeted control measures, particularly in bovine populations.