Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Gualtar Campus, 4710-057, Braga, Portugal.
ICVS/3B's, PT Government Associate Laboratory, Braga/4805-017, 4710-057, Guimarães, Portugal.
BMC Infect Dis. 2018 Jan 25;18(1):53. doi: 10.1186/s12879-018-2968-1.
Tuberculosis (TB) incidence is decreasing worldwide and eradication is becoming plausible. In low-incidence countries, intervention on migrant populations is considered one of the most important strategies for elimination. However, such measures are inappropriate in European areas where TB is largely endemic, such as Porto in Portugal. We aim to understand transmission chains in Porto through a genetic characterization of Mycobacterium tuberculosis strains and through a detailed epidemiological evaluation of cases.
We genotyped the M. tuberculosis strains using the MIRU-VNTR system. We performed an evolutionary reconstruction of the genotypes with median networks, used in this context for the first time. TB cases from a period of two years were evaluated combining genetic, epidemiological and georeferencing information.
The data reveal a unique complex scenario in Porto where the autochthonous population acts as a genetic reservoir of M. tuberculosis diversity with discreet episodes of transmission, mostly undetected using classical epidemiology alone.
Although control policies have been successful in decreasing incidence in Porto, the discerned complexity suggests that, for elimination to be a realistic goal, strategies need to be adjusted and coupled with a continuous genetic characterization of strains and detailed epidemiological evaluation, in order to successfully identify and interrupt transmission chains.
结核病（TB）的发病率在全球范围内呈下降趋势，消除结核病已成为可能。在发病率较低的国家，针对移民群体的干预被认为是消除结核病的最重要策略之一。然而，在结核病广泛流行的欧洲地区，如葡萄牙的波尔图，这种措施并不合适。我们旨在通过对结核分枝杆菌菌株进行基因特征分析，并对病例进行详细的流行病学评估，来了解波尔图的传播链。
我们使用 MIRU-VNTR 系统对结核分枝杆菌菌株进行基因分型。我们使用中位数网络进行了基因型的进化重建，这在该背景下是首次使用。我们结合遗传、流行病学和地理参考信息，对两年期间的结核病病例进行了评估。
数据揭示了波尔图独特而复杂的情景，当地居民是结核分枝杆菌多样性的遗传库，存在离散的传播事件，仅通过传统的流行病学方法很难发现这些事件。
尽管控制政策已成功降低了波尔图的发病率，但所发现的复杂性表明，为了实现消除结核病的目标，需要调整策略并结合对菌株的连续基因特征分析和详细的流行病学评估，以成功识别和中断传播链。
