Tuberculosis

肺结核

Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026

Tuberculosis represents a major global health challenge, ranking among the top causes of mortality from infectious agents worldwide ^[1]^[2]. Caused by Mycobacterium tuberculosis bacteria that predominantly infect pulmonary tissue, the condition affects approximately one-quarter of the global population through latent colonization ^[3]^[4]. While most carriers remain asymptomatic and non-contagious, a subset progresses to active illness characterized by significant morbidity and geographic clustering in resource-limited regions ^[4]^[2]. Despite established curative pathways, persistent socioeconomic determinants and healthcare access gaps sustain its substantial annual disease burden ^[1]^[2].

Read the full clinical and epidemiological profile 6

Definition

Tuberculosis is an infectious pathology driven by Mycobacterium tuberculosis bacilli that typically localizes to the respiratory tract but possesses the capacity to disseminate to extrapulmonary sites such as the central nervous system, renal structures, and skeletal framework ^[3]^[4]. Clinical manifestation hinges on bacterial proliferation within host tissues, distinguishing latent colonization from symptomatic active disease ^[3]. The pathological continuum spans from asymptomatic microbial persistence to progressive organ involvement requiring targeted antimicrobial intervention ^[4].

Clinical features

Active clinical presentation commonly features prolonged cough, systemic fever, and unintended somatic decline, though symptom intensity frequently remains subtle or entirely absent during initial phases ^[1]^[3]. This indolent progression complicates early recognition, necessitating heightened clinical vigilance even in the absence of overt complaints ^[4]. When manifestations emerge, they correlate with anatomical involvement, with pulmonary signs predominating alongside potential extrapulmonary neurological or renal indicators ^[3]. Definitive identification typically depends on sputum analysis utilizing rapid molecular diagnostics, often supplemented by thoracic imaging to assess structural involvement ^[1].

Epidemiology

Globally, tuberculosis maintains a substantial mortality footprint, consistently ranking as a primary driver of infectious disease-related deaths across diverse populations ^[1]. Disease exposure concentrates markedly in high-incidence environments where environmental and socioeconomic factors amplify transmission likelihood ^[1]. Progression from initial bacterial encounter to active clinical illness demonstrates temporal clustering, with elevated susceptibility concentrated within the initial years following exposure ^[1]. These distribution patterns underscore the necessity for targeted surveillance in densely populated or resource-constrained regions where exposure dynamics intensify ^[1].

Transmission

Pathogen dissemination occurs exclusively through aerosolized respiratory droplets expelled during coughing, sneezing, or expectoration by individuals harboring active pulmonary infection ^[3]^[2]. Inhalation of minute quantities of airborne bacilli suffices to initiate colonization in susceptible hosts sharing enclosed airspace ^[2]. Contagiousness remains strictly confined to those with clinically active respiratory disease, as asymptomatic carriers do not facilitate onward spread ^[3]. Environmental ventilation quality and proximity to infectious individuals critically modulate transmission probability within shared settings ^[1].

Prevention

Population-level control heavily emphasizes comprehensive case management and rifamycin-containing therapeutic regimens to eliminate reservoirs of active infection and interrupt community transmission chains ^[1]. Immunization frameworks in endemic territories deploy the Bacille Calmette-Guérin vaccine to mitigate severe pediatric outcomes and reduce infant mortality associated with aggressive disease variants ^[3]. Public health implementation integrates structured adherence protocols, including directly observed therapy, to optimize treatment completion rates and minimize resistance development ^[5]. Concurrent efforts prioritize modifying underlying vulnerability factors through nutritional optimization, substance use reduction, and metabolic disease management to curb progression trajectories ^[1].

References

1 Trajman A et al. Tuberculosis. Lancet. 2025 Mar 8. PMID: 40057344. doi: 10.1016/S0140-6736(24)02479-6. PubMed: https://pubmed.ncbi.nlm.nih.gov/40057344/
2 World Health Organization. Tuberculosis [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/health-topics/tuberculosis
3 World Health Organization. Tuberculosis [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/tuberculosis
4 World Health Organization. Tuberculosis [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/news-room/questions-and-answers/item/tuberculosis
5 Nahid P et al. Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: Treatment of Drug-Susceptible Tuberculosis. Clin Infect Dis. 2016 Oct 1. PMID: 27516382. doi: 10.1093/cid/ciw376. PubMed: https://pubmed.ncbi.nlm.nih.gov/27516382/