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Background: 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. Aim: 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. Methods: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

Background: Brucellosis is an emerging yet neglected zoonosis that has been reported in Kenya. Epidemiological data on brucellosis in ruminants is readily accessible; however, reports on brucellosis in pigs remain limited. This study sought to detect Brucella infection in pig serum by both serological and molecular techniques. Serum from 700 pigs randomly collected at a centralized abattoir in Nairobi region, Kenya were screened in parallel, using both Rose Bengal Test (RBT) and competitive Enzyme-Linked Immuno-sorbent Assay (cELISA) for antibodies against Brucella spp. All sera positive by RBT and 16 randomly selected negative samples were further tested using conventional PCR targeting bcsp31 gene and real-time PCR (RT-PCR) assays targeting IS711 and bcsp31 genes. Results: A prevalence of 0.57% (n = 4/700) was estimated using RBT; none of these samples was positive on cELISA. All RBT positive sera were also positive by both PCRs, while two sero-negative samples also tested positive on RT-PCR (n = 6/20). Brucella abortus was detected in four out of the six PCR positive samples through a real-time multiplex PCR. Conclusion: The detection of antibodies against Brucella spp. and DNA in serum from slaughterhouse pigs confirm the presence of Brucella in pigs. Therefore, investigation of the epidemiology and role of pigs in the transmission of brucellosis in Kenya is needed. Further targeted studies would be useful to systematically quantify and identify the spp. of Brucella in pigs. [ABSTRACT FROM AUTHOR]

Human brucellosis diagnosis has been a challenge in Brucella-endemic areas. In Kenya, diagnosis is usually carried out using Febrile Brucella Antigen agglutination test (FBAT) whose performance is not well documented. This paper reports on the sensitivity and specificity of the FBAT used for brucellosis diagnosis on blood samples/serum collected in three healthcare facilities in Baringo County, Kenya, and on Brucella species present in the study area. The FBAT test results at the hospitals were used to guide patient management. Patients who visited the hospital's laboratory with a clinician's request for brucellosis testing also filled a questionnaire to assess knowledge and attitudes associated with transmission of the disease in the study area. The remaining serum samples were tested again using FBAT and Rose Bengal Plate Test (RBPT) within a month of blood collection at the University Nairobi Laboratory. The two rapid tests were then compared, with respect to brucellosis diagnostic sensitivity and specificity. To identify infecting Brucella species, a proportion 43% (71/166) of the blood clots were analyzed by multiplex polymerase chain reaction (PCR) using specific primers for B. abortus, B. melitensis, B. ovis and B. suis. Out of 166 serum samples tested, 26.5% (44/166) were positive using FBAT and 10.2% (17/166) positive using RBPT. The sensitivity and specificity of FBAT compared to RBPT was 76.47% and 71.19%, respectively while the positive and negative predictive values were 29.55% and 96.72%, respectively. The FBAT showed higher positivity then RBPT. The difference in sensitivity and specificity of FBAT and RBPTs was relatively low. The high FBAT positivity rate would be indication of misdiagnosis; this would lead to incorrect treatment. Brucella abortus was detected from 9.9% (7/71) of the blood clots tested; no other Brucella species were detected. Thus human brucellosis, in Baringo was mainly caused by B. abortus., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Waringa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The Rose-Bengal plate test (RBPT) was performed on 488 patients with flu-like symptoms from Narok district. There was poor agreement between RBPT results from four health facilities in Narok and from the central veterinary laboratory (CVL). Agreement was poorer for the three rural dispensaries than for the District Hospital. On the other hand, for tests conducted at the CVL, there was good agreement between RBPT, serum agglutination test (SAT) and complement fixation test (CFT) results, indicating that all these tests were probably performing well. Better training and quality control and the use of white rather than a clear background surface for judging agglutination results are recommended to improve the performance of test results in Narok District health facilities.

Monthly disease summary sheets from 1986-1992 of 60 dispensaries, clinics and hospitals in Narok district, Kenya were reviewed for the occurrence of brucellosis and other diseases with "flu-like symptoms". Diseases with these symptoms accounted for about 52% of the 1,037,875 cases reported for the time period. These were classified as malaria (79.3%), rheumatism (7.1%), PUO (2.4%), and brucellosis (0.8%). Brucellosis was diagnosed by a positive Rose Bengal (RB) test routinely conducted in seven out of the 60 health units. In these units, 55% of flu-like cases were classified as malaria and 21.2% as brucellosis. Individual case records of patients at four dispensaries using the RB test during 1991-92 were assessed for specific predictor symptoms. For 625 RB tested patients, a positive test result was associated with joint pain, headache, and the combinations of joint pain with headache and lameness with headache. A logistic regression model correctly predicted the RB test result in 62.3% of the time. For the 465 patients examined by the blood smear examination, identification of malaria parasites was associated with, headache, joint pain and combinations of emesis with pale mucous membranes. This regression model correctly predicted positive results 67.2% of the time. Both models indicate that selected clinical predictors represented significantly increased odds of being positive to the respective tests. However, for both diseases, clinical signs alone appear insufficient for reliable diagnosis and differentiation probably due to resemblance in symptomatology between these two and other diseases.

In Machakos Hospital, Kenya, the sera of 452 patients suspected of brucellosis were examined with the Rose Bengal Plate Test (RBPT), the complement fixation test (CFT) and the tube serum agglutination test (SAT). The percentage of false positive findings on the RBPT was 0.22% when compared with the SAT, 0.44% with the CFT. The percentage of false negative findings on the RBPT was 3% when compared with the SAT, 0.88% with the CFT. A good correlation between the RBPT and both the SAT and the CFT was also found by Morgan et al. (1969). The RBPT may be considered as a highly reliable test in the diagnosis of human brucellosis. The test is especially valuable in areas where laboratory facilities are not available and can be used as a screening test in areas with good laboratory facilities.