Apex University School of Medicine, and UNZA-UCLMS Research and Training Program, Lusaka, Zambia.
Department of Medicine, Kenyatta University, Nairobi, Kenya.
Int J Infect Dis. 2020 Mar;92S:S69-S71. doi: 10.1016/j.ijid.2020.02.011. Epub 2020 Feb 28.
An estimated 1.8 billion people worldwide have a latent tuberculosis infection (LTBI), with wide variations in LTBI rates across countries. LTBI can be due to infection with either drug-sensitive or drug-resistant Mycobacterium tuberculosis (Mtb) strains. Accurate data on the prevalence of LTBI due to multidrug-resistant (MDR) Mtb strains are unavailable, since the strains cannot be isolated for resistance testing. There are no 'gold standard' tests for accurately diagnosing LTBI. Only three tests are currently available and approved by the World Health Organization (WHO) for the diagnosis of LTBI: the now outdated tuberculin skin test (TST), developed a century year ago, and the two interferon-gamma release assays (IGRAs) developed and rolled out over the past decade, the QuantiFERON (Qiagen, Germany) and T-SPOT.TB (Oxford Immunotec, United Kingdom) tests. These latter tests are not ideal due to issues of sensitivity, specificity, inability to distinguish infection with MDR-Mtb strains, and high costs. Achieving the WHO End TB Strategy target of an 80% reduction in global TB incidence by 2030 will require a major reduction in the number of persons with LTBI progressing to active TB disease. Critical to this will be the development of new diagnostic tests that are better than currently available LTBI tests at predicting who is at risk of progression to active TB disease. The diagnostic product development portfolio for LTBI appears to have reached the end of the road. Every attempt to make optimal use of currently available IGRAs using WHO LTBI guidelines for LTBI testing and treatment must be made to achieve WHO End TB strategy targets.
据估计，全球有 18 亿人患有潜伏性结核感染（LTBI），各国 LTBI 发病率差异很大。LTBI 可能是由于感染了敏感或耐药的结核分枝杆菌（Mtb）菌株引起的。由于无法分离耐药菌株进行耐药性检测，因此无法获得关于耐多药（MDR）Mtb 菌株所致 LTBI 患病率的准确数据。目前尚无准确诊断 LTBI 的“金标准”检测方法。只有三种检测方法目前可供使用，并获得世界卫生组织（WHO）的批准，可用于 LTBI 的诊断：现已过时的结核菌素皮肤试验（TST），该方法在一个世纪前开发，以及过去十年开发并推出的两种干扰素-γ释放测定（IGRAs），即 QuantiFERON（Qiagen，德国）和 T-SPOT.TB（Oxford Immunotec，英国）试验。这些检测方法并不理想，因为它们存在敏感性、特异性、无法区分 MDR-Mtb 菌株感染以及成本高的问题。要实现 2030 年全球结核病发病率降低 80%的世卫组织终结结核病战略目标，就必须大幅减少 LTBI 进展为活动性结核病的人数。这关键在于开发新的诊断检测方法，使其在预测谁有进展为活动性结核病的风险方面优于现有的 LTBI 检测方法。LTBI 的诊断产品开发组合似乎已经走到了尽头。必须尽一切努力，按照世卫组织 LTBI 检测和治疗指南，充分利用现有的 IGRAs，以实现世卫组织终结结核病战略目标。
