Brucellosis is an important zoonotic disease occurring worldwide. In animals, it causes reproductive failures such as abortions, stillbirths or birth of unthrifty neonates, orchitis, seminal vesiculitis, testicular abscesses and epididymitis in males, as well as localised chronic conditions such as hygroma and arthritis. Humans are infected by exposure to infected animals or animal products. Brucellosis in humans causes intermittent fever, body ache, arthritis and hygromas. Brucellosis results in economic loss to the farmer, high treatment costs and loss of man-hours. Brucellosis prevention and control will improve livestock productivity, leading to improved economic status of the farmers and reduce infections in humans. Data on the disease situation for particular areas will help the relevant authorities put up educational and control measures for the area; the measures can then be extrapolated and tailor-made for other areas in Kenya.
This paper reports on a cross-sectional study carried out in Baringo Central, Mogotio, Baringo South (in Marigat) and Eldama Ravine sub-counties in Baringo County. It involved serological testing using serum and milk, detection of Brucella DNA through PCR, and establishing factors associated with the disease occurrence through analysis of filled questionnaires. Farms were randomly selected from each sub-county and blood from selected cattle (n= 250), sheep (n= 142) and goats (n= 166) collected in sterile plain vacutainer bottles, for serum and blood clots. Bulk raw cattle milk (n=83) was also collected. Risk estimates for Brucellosis infection were calculated.
Twenty three (9.2%) of the 250 cattle serum samples reacted positive to Rose Bengal Plate test (RBPT) while 17 (6.8%) reacted positive to cELISA, with cumulative reactors of 25 (10%). The 166 caprine serum samples had 17 (10.2%) positive reactors to RBPT and 11 (6.6%) by cELISA; cumulative caprine reactors were 18 (10.8%). Positive ovine serum samples were 10 (7%) and 7 (4.9%) on RBPT and cELISA, respectively; yielding positive cumulative reactors of 11 (7.7%). The sensitivity and specificity of RBPT, with respect to cELISA, was 88.6% and 96.4%, respectively with a predictive value positive of 62% and predictive value negative of 99%. The overall Brucella positivity on the bulk milk samples was 9.5% with positivity in the sub-counties as 16.7% for Baringo South, 11.8% for Mogotio, 3.6% for Baringo Central and 6.7% for Eldama Ravine. Brucella abortus DNA was detected in 11 of cattle, in two goats and in one sheep blood clots. Brucella melitensis DNA was detected in one goat blood clot only.
Risk factors associated with brucellosis in the region were: allowing animals to calve down in pasture, risk estimate 8.5 (range 2.8 â€“ 16.8); communal watering 7 (range 2.8 â€“ 16.8) and communal grazing 2.4 (range 1.2 â€“ 4.5). Introduction of a new animal, reported by 42% of the respondents, was found not to be a risk factor despite studies elsewhere documenting it as one. A total of 12.7% (10/79) respondents did not know how humans get brucellosis.
This study established that brucellosis occurs in livestock in Baringo County, and that the predominant causative species is B. abortus. The study also established that over 10% of the people in the area were not aware of the risk factors associated with the disease; hence they were easily exposed and infected. It is therefore recommended that awareness campaigns be organised in the region, to enlighten the farmers/residents on the significance of the disease, its transmission and control measures that they can practice. This will aid in lowering the prevalence of the disease in animals and will go a long way towards minimizing human brucellosis.
Keywords: Brucellosis, Baringo, livestock, prevalence, zoonosis