The sero-prevalence of brucellosis in cattle and their herders in Bahr el Ghazal region, South Sudan

Abstract

BackgroundBrucellosis is a worldwide recognized bacterial zoonotic disease. There is currently no information on bovine brucellosis sero-prevalence in South Sudan regardless of the economic, social and public health impact on populations. Therefore, for the first time in 33 years, we report the sero-prevalence of brucellosis in cattle and their herders. Furthermore, we characterize the drivers associated with the disease at the human-animal interface in Bahr el Ghazal region, South Sudan.MethodsA total of 893 and 87 animal and human sera respectively were examined between December 2015 and May 2016. Rose Bengal Plate Test (RBPT) and Competitive Enzyme Linked Immuno Sorbent Assay (c-ELISA) were used in parallel to detect anti-Brucella antibodies. Questionnaires were administered to collect relevant metadata used for the association analysis in R version 3.2.3. Odds Ratio (OR) and Confidence Intervals (CI) were determined.ResultsOverall bovine brucellosis prevalence was 31% (95%CI = 28.0–34.2), with the highest 63% (95%CI = 53–70) and lowest 10% (95%CI = 4.5–20.1) prevalence estimates in Wau and Gogrial states respectively. The bovine sero-prevalence was approximately equally distributed among the male 30.4% (26.9–34.2) and the females 32.5% (26.8–38.7). Poor body condition (OR = 0.22; 95%CI = 0.07–0.54) and larger herd sizes (OR = 0.05; 95%CI = 0.008–0.173) were protective factors for brucellosis, while the opposite was true for the second (OR = 1.70; 95%CI = 1.08–2.67) and third (OR = 2.5; 95%CI = 1.46–4.47) lactation stage. The overall brucellosis sero-prevalence in herders was estimated at 33.3% (23.9–44.3).ConclusionWe report a high prevalence of anti-Brucella antibodies in cattle and their herders in Bahr el Ghazal, indicating an enzootic status in the cattle population being an important source of infection for humans. This represents a genuine public health challenge. Therefore, there is need to raise awareness and build capacity and infrastructure in this fragile state to underwrite future public health strategies for brucellosis.

Detection of Brucella abortus and Brucellla melitensis in cattle and sheep from southern Cameroon

“…In fact, cattle remain in the herd for many years and therefore, are more exposed to Brucella infections than sheep. This hypothesis is in agreement with previous observations reporting that as long as infected animals remain in contact with the rest of the herd, the number of infected animals will increase [10,35,36,37].…”

“…During the last decades, several investigations have been undertaken to determine the sero-prevalence of Brucella antibodies in sub-Saharan African countries [7,10,11,13,14]. Although most of these investigations demonstrated contacts between Brucella and various hosts including humans and different animal species, the identity of bacteria species that are responsible for the production of Brucella' antibodies has not been deeply investigated.…”

“…In most sub-Saharan African countries, investigations undertaken on brucellosis have been mainly based on Brucella antibodies detection using various serological tests like the Rose Bengal Plate Test (RBPT), Enzyme Linked Immunosorbent assay (ELISA), complement fixation test [7,10,11,12,13,14].…”

“…Even though serological tests have generated epidemiological data on the sero-prevalence of Brucella antibodies in humans and domestic animals of several sub-Saharan countries, these tests cannot differentiate different Brucella species [7,10,11,13]. Moreover, the host species for each Brucella species remain not well known.…”

Presumptive diagnosis of brucellosis and determination of risk factors for seropositivity among members of cattle keeping households in a high cattle traffi c area in the South Western region of Uganda

“…From this study, more than a third (34.7%) of the animals sampled were presumptively seropositive, this is in line with fi eld reports from animal service providers, who non-routinely carry out Brucella screening in livestock in this western region and had persistently reported an increase in seroprevalence. This seroprevalence is within the range of the one in a study that was carried out in South Sudan (31%) where RBT was used [23]. The RBT was used qualitatively and disease confi rmation was not done because titres were not taken, never the less, presumptive herd seroprevalence of 71% was considered high and as a matter of serious public and veterinary health concern since animals solely indirectly or directly infect humans and serious economic losses occur when animals have brucellosis [34].…”