Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China.
Inner Mongolia Autonomous Region Center for Comprehensive Disease Control and Prevention, Huhhot, China.
Transbound Emerg Dis. 2020 Mar;67(2):834-843. doi: 10.1111/tbed.13404. Epub 2019 Nov 15.
Brucellosis is a global pandemic infectious zoonosis. Brucella canis is a rare source of human brucellosis in China, and its public health significance remains under debate. Moreover, data pertaining to the epizootiological characteristics and geographical origin of B. canis on a nationwide scale are limited, and the risk to public safety posed by B. canis infections is unknown. The MLVA (multilocus variable-number tandem repeat analysis) assay can be helpful to analyse epidemiological correlations among Brucella isolates and to track their geographic origins. To accomplish this task, MLVA-16 was used to analyse the epidemiological links of 63 isolates obtained from dogs and humans. Sixty-three B. canis strains were sorted into three large clusters (A, B and C) and 50 different genotypes (GT1-50), and 43 unique genotypes were represented by single isolates, suggesting that these strains had no obvious epidemiological links and that canine brucellosis is predominantly sporadic in China. The other seven shared genotypes (among a total of 20 isolates) were each represented by two to eight isolates, indicating that strains from each shared genotype were epidemiologically correlated. Five of the shared genotypes were from 16 strains obtained from Beijing, indicating that canine brucellosis in Beijing originates from multipoint outbreaks with multiple sources of infection. Based on comprehensive case analysis of clinical B. canis infection, we preliminarily suggest that human B. canis infections are associated with Mycoplasma pneumoniae infection that results in decreased patient immunity. B. canis may have limited epidemiological significance for the healthy population, but it remains a significant threat to the canine breeding industry and to humans who come into close contact with dogs. Based on MLVA-11 data, B. canis strains were clustered into 16 genotypes and divided into five evolutionary branches; these data confirm that this population covers an extensive geographic area and exhibits characteristics of the origin and evolution of co-existing introduced and locally native lineages. We believe this study will contribute to strengthening efforts to prevent and control canine brucellosis and to improve public understanding of the health risks posed by B. canis.
布鲁氏菌病是一种全球性的流行人畜共患传染病。在中国，犬种布鲁氏菌是人类布鲁氏菌病的罕见来源，其公共卫生意义仍存在争议。此外，关于全国范围内犬种布鲁氏菌的流行病学特征和地理来源的数据有限，犬种布鲁氏菌感染对公众安全构成的风险尚不清楚。MLVA（多位点可变数目串联重复分析）检测可有助于分析布鲁氏菌分离株的流行病学相关性，并追踪其地理来源。为了完成这项任务，使用 MLVA-16 分析了从狗和人类中获得的 63 株分离株的流行病学联系。63 株犬种布鲁氏菌分为 3 个大簇（A、B 和 C）和 50 个不同的基因型（GT1-50），43 个独特的基因型由单个分离株代表，表明这些菌株没有明显的流行病学联系，中国的犬布鲁氏菌病主要是散发性的。另外 7 个共享基因型（在总共 20 个分离株中）分别由 2 到 8 个分离株代表，表明来自每个共享基因型的菌株在流行病学上是相关的。其中 5 个共享基因型来自北京的 16 株分离株，表明北京的犬布鲁氏菌病起源于多点暴发，有多种感染源。基于对临床犬种布鲁氏菌感染的综合病例分析，我们初步提出人类犬种布鲁氏菌感染与导致患者免疫力下降的肺炎支原体感染有关。犬种布鲁氏菌对健康人群的流行病学意义可能有限，但它仍然对犬只养殖行业和与狗密切接触的人类构成重大威胁。基于 MLVA-11 数据，犬种布鲁氏菌分离株聚类为 16 个基因型，并分为 5 个进化分支；这些数据证实该种群覆盖了广泛的地理区域，并具有共存的引入和本地原生谱系起源和进化的特征。我们相信这项研究将有助于加强犬布鲁氏菌病的预防和控制，并提高公众对犬种布鲁氏菌健康风险的认识。
