Department of Clinical Veterinary Studies,Faculty of Veterinary Science,University of Zimbabwe,PO Box MP 167,Mt. Pleasant, Harare,Zimbabwe.
Department of Veterinary Tropical Diseases,Faculty of Veterinary Science,University of Pretoria,Private Bag X 04,Onderstepoort 0110,Pretoria,South Africa.
Epidemiol Infect. 2018 Sep;146(12):1526-1532. doi: 10.1017/S0950268818001577. Epub 2018 Jun 14.
Anthrax is an important disease caused by the bacterium Bacillus anthracis affecting both domestic and wild animals at the wildlife/livestock interface, defined here as a physical space in which wild and domestic species overlap in range and potentially interact. In endemic regions, sporadic anthrax outbreaks occur, causing significant deaths of both wildlife and livestock and sporadically, humans. However, it may also occur as isolated outbreaks with a few animals affected. Such isolated anthrax outbreaks maybe missed. High seroprevalence among carnivores suggests either regular non-fatal exposure to the pathogen circulating in a given environment, or contact with missed cases through consumption of anthrax carcases. To investigate the relevance of this potential indicator, a cross-sectional study was conducted to determine anthrax seroprevalence in domestic dogs (Canis lupus familiaris) from selected interface and non-interface areas of Zimbabwe with known history of anthrax outbreaks. Based on past anthrax outbreaks in the respective areas, the sites were further classified as high or low risk areas for anthrax outbreaks. Sera were collected from domestic dogs (n = 186) and tested for antibodies against B. anthracis protective antigens (PA) using an ELISA test. The overall seroprevalence was 51.6% (96/186; 95% CI 44.2-59.0). Sites from the non-interface areas recorded a significantly (P < 0.001) higher (72.1%) anthrax seroprevalence compared with those from the wildlife -livestock interface (41.5%). The results demonstrated a strong association (χ2 = 14.3; OR = 3.2, 1.6 < OR < 6.2, P < 0.001) between anthrax seropositivity and interface type. Low-risk sites (42.5%) had a significantly (P = 0.044) lower seroprevalence compared with high-risk sites (58.5%) but still demonstrated high seroprevalence for areas where anthrax was last reported more than 20 years back. Dogs from Tsholotsho South were more than 90-times (OR = 96.5, 13.5 < OR < 690.8) more likely to be seropositive compared with those from Hwange. The study demonstrated the potential to use domestic dogs as indicators of anthrax in the study areas to survey anthrax circulation in supposed low-risk areas and calls for a redefinition of both low and high risk areas for anthrax in Zimbabwe based on an improved surveillance.
炭疽是一种由炭疽杆菌引起的重要疾病，影响到野生动物/牲畜界面上的家养和野生动物，这里定义为野生动物和家养物种在范围上重叠并可能相互作用的物理空间。在流行地区，零星的炭疽暴发会导致野生动物和家畜大量死亡，偶尔也会导致人类死亡。然而，它也可能以少数动物受影响的孤立暴发形式出现。这种孤立的炭疽暴发可能会被遗漏。食肉动物中的高血清阳性率表明，它们要么经常接触到在特定环境中循环的病原体，但没有致命影响，要么通过食用炭疽尸体接触到被遗漏的病例。为了研究这种潜在指标的相关性，进行了一项横断面研究，以确定津巴布韦具有已知炭疽暴发历史的选定界面和非界面地区的家养犬（Canis lupus familiaris）的炭疽血清阳性率。根据各自地区过去的炭疽暴发情况，这些地点进一步分为高风险或低风险炭疽暴发区。从家养犬（n=186）采集血清，并用 ELISA 试验检测针对炭疽杆菌保护性抗原（PA）的抗体。总血清阳性率为 51.6%（96/186；95%CI 44.2-59.0）。来自非界面地区的地点的炭疽血清阳性率明显（P<0.001）高于来自野生动物-牲畜界面地区的地点（72.1%）。结果表明，炭疽血清阳性率与界面类型之间存在很强的关联性（χ2=14.3；OR=3.2，1.6<OR<6.2，P<0.001）。低风险地点（42.5%）的血清阳性率明显（P=0.044）低于高风险地点（58.5%），但在过去 20 年以上报告有炭疽病例的地区，仍显示出较高的血清阳性率。来自 Tsholotsho South 的犬比来自 Hwange 的犬更容易出现血清阳性，其可能性超过 90 倍（OR=96.5，13.5<OR<690.8）。该研究表明，在研究地区，使用家养犬作为炭疽的指示剂来调查假定低风险地区的炭疽循环是有潜力的，并呼吁根据改进的监测重新定义津巴布韦的低风险和高风险地区。
