Department of Medical Microbiology and Immunology, University of Nairobi, Nairobi, Kenya.
International Livestock Research Institute, Nairobi, Kenya.
PLoS Negl Trop Dis. 2023 Oct 16;17(10):e0011682. doi: 10.1371/journal.pntd.0011682. eCollection 2023 Oct.
Brucellosis is a neglected zoonotic disease that affects both animals and humans, causing debilitating illness in humans and socio-economic losses in livestock-keeping households globally. The disease is endemic in many developing countries, including Kenya, but measures to prevent and control the disease are often inadequate among high-risk populations. This study aimed to investigate the human and livestock seroprevalence of brucellosis and associated risk factors of Brucella spp. in a pastoralist region of northern Kenya.
A cross-sectional survey was conducted using a two-stage cluster sampling method to select households, livestock, and humans for sampling. Blood samples were collected from 683 humans and 2157 animals, and Brucella immunoglobulin G (IgG) antibodies were detected using enzyme-linked immunosorbent assays. A structured questionnaire was used to collect data on potential risk factors associated with human and animal exposures. Risk factors associated with Brucella spp. exposures in humans and livestock were identified using Multivariate logistic regression.
The results indicated an overall livestock Brucella spp. seroprevalence of 10.4% (95% Confidence Interval (CI): 9.2-11.7). Camels had the highest exposure rates at 19.6% (95% CI: 12.4-27.3), followed by goats at 13.2% (95% CI: 9.3-17.1), cattle at 13.1% (95% CI: 11.1-15.3) and sheep at 5.4% (95% CI: 4.0-6.9). The herd-level seroprevalence was 51.7% (95% CI: 47.9-55.7). Adult animals (Adjusted Odds Ratio (aOR) = 2.3, CI: 1.3-4.0), female animals (aOR = 1.7, CI: 1.1-2.6), and large herd sizes (aOR = 2.3, CI: 1.3-4.0) were significantly associated with anti-brucella antibody detection while sheep had significantly lower odds of Brucella spp. exposure compared to cattle (aOR = 1.3, CI: 0.8-2.1) and camels (aOR = 2.4, CI: 1.2-4.8). Human individual and household seroprevalences were 54.0% (95% CI: 50.2-58.0) and 86.4% (95% CI: 84.0-89.0), respectively. Significant risk factors associated with human seropositivity included being male (aOR = 2.1, CI:1.3-3.2), residing in Sericho ward (aOR = 1.6, CI:1.1-2.5) and having no formal education (aOR = 3.0, CI:1.5-5.9). There was a strong correlation between human seropositivity and herd exposure (aOR = 1.6, CI:1.2-2.3).
The study provides evidence of high human and livestock exposures to Brucella spp. and identifies important risk factors associated with disease spread. These findings emphasize the need for targeted prevention and control measures to curb the spread of brucellosis and implement a One Health surveillance to ensure early detection of the disease in Isiolo County, Northern Kenya.
布氏杆菌病是一种被忽视的人畜共患疾病，会影响动物和人类，使人类患病，使畜牧业家庭遭受社会经济损失。这种疾病在许多发展中国家流行，包括肯尼亚，但高危人群中预防和控制这种疾病的措施往往不足。本研究旨在调查肯尼亚北部一个牧民地区人类和牲畜布鲁氏菌病的血清流行率及布鲁氏菌属的相关危险因素。
采用两阶段整群抽样方法进行横断面调查，选择家庭、牲畜和人类进行采样。采集 683 名人类和 2157 头动物的血液样本，采用酶联免疫吸附试验检测布鲁氏菌免疫球蛋白 G（IgG）抗体。使用结构化问卷收集与人类和动物接触相关的潜在危险因素数据。采用多变量逻辑回归识别与布鲁氏菌属接触相关的人类和动物的危险因素。
结果表明，牲畜布鲁氏菌属总血清流行率为 10.4%（95%置信区间：9.2-11.7）。骆驼的暴露率最高，为 19.6%（95%置信区间：12.4-27.3），其次是山羊，为 13.2%（95%置信区间：9.3-17.1），牛为 13.1%（95%置信区间：11.1-15.3），绵羊为 5.4%（95%置信区间：4.0-6.9）。畜群水平的血清流行率为 51.7%（95%置信区间：47.9-55.7）。成年动物（调整优势比（aOR）=2.3，95%置信区间：1.3-4.0）、雌性动物（aOR=1.7，95%置信区间：1.1-2.6）和大畜群（aOR=2.3，95%置信区间：1.3-4.0）与抗布鲁氏菌抗体检测显著相关，而与牛（aOR=1.3，95%置信区间：0.8-2.1）和骆驼（aOR=2.4，95%置信区间：1.2-4.8）相比，绵羊的布鲁氏菌属暴露几率显著较低。人类个体和家庭的血清流行率分别为 54.0%（95%置信区间：50.2-58.0）和 86.4%（95%置信区间：84.0-89.0）。与人类血清阳性相关的显著危险因素包括男性（aOR=2.1，95%置信区间：1.3-3.2）、居住在 Sericho 区（aOR=1.6，95%置信区间：1.1-2.5）和没有正规教育（aOR=3.0，95%置信区间：1.5-5.9）。人类血清阳性与畜群暴露之间存在很强的相关性（aOR=1.6，95%置信区间：1.2-2.3）。
本研究提供了人类和牲畜接触布鲁氏菌属的高暴露证据，并确定了与疾病传播相关的重要危险因素。这些发现强调需要采取有针对性的预防和控制措施，以遏制布氏杆菌病的传播，并实施一项以人群为基础的监测措施，以确保在肯尼亚北部的伊西奥洛县早期发现该疾病。
