Tuberculosis

What is Tuberculosis?

Tuberculosis (TB) is a potentially serious infectious disease caused by bacteria called Mycobacterium tuberculosis. While TB primarily affects the lungs (pulmonary tuberculosis), it can also spread to other parts of the body including the kidneys, spine, and brain (extrapulmonary tuberculosis). TB remains one of the world’s leading infectious killers, particularly affecting people with weakened immune systems. Despite being preventable and curable, TB continues to pose a significant global health challenge, especially in developing countries and among vulnerable populations.

Key statistics

Global incidence	10.6 million new cases annually
Annual deaths	1.3 million deaths worldwide
Latent TB prevalence	Approximately 2 billion people (25% of global population)
Peak age range	15-45 years, though all ages can be affected

Symptoms

Common symptoms include persistent cough lasting more than three weeks, chest pain, coughing up blood or sputum, weakness or fatigue, weight loss, loss of appetite, chills, fever, and night sweats.

Early symptoms: A persistent cough that gradually worsens is often the first sign of pulmonary TB. This may initially be dry but typically becomes productive, meaning it brings up phlegm or sputum. Mild fever and night sweats may also occur early in the disease process.

Progressive symptoms: As the infection advances, patients may experience significant weight loss and loss of appetite, leading to a wasted appearance historically known as “consumption.” Fatigue and weakness become more pronounced, and the cough may produce blood-streaked sputum.

Severe symptoms: Advanced pulmonary TB can cause severe chest pain, difficulty breathing, and coughing up significant amounts of blood. Extrapulmonary TB symptoms depend on the affected organs but may include back pain (spinal TB), confusion or headaches (TB meningitis), or abdominal pain (abdominal TB).

Causes and risk factors

TB is caused by infection with Mycobacterium tuberculosis, which spreads through airborne droplets when someone with active pulmonary TB coughs, sneezes, speaks, or sings. Not everyone exposed to TB bacteria develops active disease; many people develop latent TB infection, where the immune system keeps the bacteria dormant.

Primary risk factors include: HIV infection (which increases TB risk by 20-30 times), diabetes mellitus, malnutrition, alcohol use disorder, tobacco smoking, chronic kidney disease, certain medications that suppress the immune system, silicosis, and certain cancers. Social determinants such as poverty, overcrowding, poor ventilation, and limited access to healthcare significantly increase transmission risk.

Geographic risk factors: Living in or traveling to areas with high TB prevalence, including parts of Africa, Asia, Eastern Europe, and Latin America. Healthcare workers and people in congregate settings like prisons or homeless shelters also face elevated risk.

Prevention

The primary prevention strategy is the Bacille Calmette-Guérin (BCG) vaccine, which is given to infants in many countries with high TB prevalence. While BCG provides some protection against severe forms of childhood TB, its effectiveness against adult pulmonary TB is variable.

Infection control measures include ensuring good ventilation in living and working spaces, covering the mouth and nose when coughing or sneezing, and isolating people with active TB until they are no longer infectious (typically after 2-3 weeks of appropriate treatment).

Treatment of latent TB infection is crucial for preventing active disease in high-risk individuals. This typically involves a course of isoniazid for 6-9 months or shorter combination regimens.

Population-level prevention includes contact tracing and screening of people exposed to active TB cases, regular screening of high-risk populations, and addressing social determinants like poverty and malnutrition that increase TB susceptibility.

Complications

Without treatment, active TB can be fatal, with mortality rates of approximately 45% for HIV-negative individuals and up to 90% for those with HIV co-infection. Even with treatment, delayed diagnosis can lead to permanent lung damage, including cavitation and fibrosis.

Pulmonary complications include massive hemoptysis (life-threatening bleeding from the lungs), pneumothorax (collapsed lung), chronic respiratory failure, and bronchiectasis (permanent widening of airways).

Extrapulmonary complications depend on the site of infection but can include TB meningitis (potentially causing permanent neurological damage), Pott’s disease (spinal TB leading to paralysis), and miliary TB (widespread dissemination throughout the body).

Treatment-related complications may include drug-resistant TB, which is much more difficult and expensive to treat, and medication side effects ranging from liver toxicity to peripheral neuropathy.

Diagnosis

TB diagnosis combines clinical assessment, radiological imaging, and laboratory testing. A chest X-ray is typically the first imaging study, often showing characteristic changes like cavities, infiltrates, or lymph node enlargement.

Microbiological diagnosis is the gold standard and includes sputum smear microscopy using acid-fast bacilli (AFB) staining, mycobacterial culture (which can take 2-8 weeks), and rapid molecular tests like GeneXpert MTB/RIF, which can detect TB bacteria and rifampin resistance within hours.

Additional tests include tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) like QuantiFERON-Gold, which help diagnose latent TB infection. CT scanning may be used for complex cases or to evaluate extrapulmonary TB.

Histological diagnosis may require tissue biopsy in cases of extrapulmonary TB or when other methods are inconclusive, showing characteristic granulomatous inflammation.

Treatment

Standard TB treatment involves a combination of antibiotics taken for at least six months. The initial intensive phase (first 2 months) typically includes four drugs: isoniazid, rifampin, ethambutol, and pyrazinamide.

The continuation phase (4 months) usually involves isoniazid and rifampin. Treatment must be completed even if symptoms improve, as stopping early can lead to drug resistance and relapse.

Drug-resistant TB requires more complex regimens. Multidrug-resistant TB (MDR-TB) is resistant to at least isoniazid and rifampin, requiring treatment with second-line drugs like bedaquiline, linezolid, and clofazimine for 18-24 months.

Directly Observed Therapy (DOT) is recommended to ensure treatment completion, where healthcare workers or trained volunteers observe patients taking their medications.

Prognosis

With appropriate treatment, drug-sensitive TB has a cure rate exceeding 95%. Most patients become non-infectious within 2-3 weeks of starting treatment and experience significant symptom improvement within the first month.

Without treatment, active TB is often fatal, particularly in immunocompromised individuals. Even among those who survive, untreated TB can cause severe disability due to lung damage or complications from extrapulmonary disease.

Drug-resistant TB has lower cure rates, with MDR-TB treatment success rates around 60-70%, and extensively drug-resistant TB (XDR-TB) success rates of approximately 30-50%. Treatment duration is longer and side effects more severe.

Long-term outcomes depend on early diagnosis and treatment completion. Patients who complete treatment typically return to normal activities, though some may have residual lung damage affecting respiratory function.

Quality of life

During active treatment, patients may experience medication side effects including nausea, fatigue, and potential liver problems, requiring regular monitoring. Most people can continue working or attending school once they’re no longer infectious, typically after 2-3 weeks of treatment.

Nutritional support is crucial, as TB often causes significant weight loss. A balanced diet rich in protein, vitamins, and calories helps recovery. Patients should avoid alcohol, which can interfere with medications and worsen liver side effects.

Mental health support is important, as TB diagnosis can cause anxiety, depression, and social stigma. Connecting with support groups and mental health professionals can be beneficial.

Exercise and activity should be gradually resumed as symptoms improve and energy returns. Initially, rest is important, but gentle exercise like walking can aid recovery once patients are no longer infectious.

Social considerations include addressing stigma through education and ensuring patients have adequate social support for treatment completion.

Pregnancy and fertility

TB can complicate pregnancy and potentially affect fertility. Untreated TB during pregnancy increases risks of maternal mortality, low birth weight, and preterm delivery.

Treatment during pregnancy is safe and essential. First-line anti-TB drugs including isoniazid, rifampin, and ethambutol are considered safe during pregnancy. Pyrazinamide is now also recommended by WHO for pregnant women.

Breastfeeding is generally safe for mothers receiving anti-TB treatment, as drug concentrations in breast milk are low. Infants born to mothers with TB should receive BCG vaccination and be monitored for TB development.

Family planning considerations include potential interactions between anti-TB drugs and hormonal contraceptives, which may reduce contraceptive effectiveness.

Children

Childhood TB often presents differently than adult disease, with more frequent extrapulmonary manifestations and higher risk of severe forms like TB meningitis and miliary TB.

Diagnosis challenges include difficulty obtaining sputum samples from young children and less characteristic X-ray findings. Contact tracing is crucial, as children typically acquire TB from adult household contacts.

Treatment modifications include weight-based dosing and liquid formulations for children who cannot swallow tablets. Treatment duration and drug combinations are generally similar to adults, though dosing requires careful calculation.

School considerations include temporary isolation until children are no longer infectious, educational support during treatment, and addressing stigma through school health programs.

BCG vaccination is particularly important for infants in high-prevalence areas, as it provides good protection against severe childhood TB forms.

When to see a doctor

Seek immediate medical attention for coughing up blood, severe chest pain, difficulty breathing, high fever with severe night sweats, or signs of TB meningitis including severe headache, neck stiffness, or confusion.

Schedule routine medical evaluation for a persistent cough lasting more than three weeks, unexplained weight loss, persistent fever, or night sweats. Anyone who has been in close contact with someone diagnosed with active TB should also seek medical evaluation.

High-risk individuals including those with HIV, diabetes, or immunosuppressive conditions should have regular TB screening and promptly report any respiratory symptoms.

Regional context

The Caucasus region experiences moderate TB burden, with Georgia reporting approximately 2,200 cases annually and drug-resistant TB rates above global averages. Armenia and Azerbaijan have implemented DOTS programs and are working to strengthen TB control measures. The region faces challenges with MDR-TB, particularly in Georgia, which has received international support for drug-resistant TB programs. Cross-border collaboration and migration patterns affect TB transmission dynamics in the region. GMJ welcomes contributions from regional researchers to build the evidence base for tuberculosis management in the Caucasus.

Research and clinical trials

Current research focuses on developing shorter treatment regimens, new drugs for drug-resistant TB, and improved rapid diagnostic tests. Recent breakthroughs include approval of pretomanid as part of combination therapy for MDR-TB.

Vaccine development remains a priority, with several candidates in clinical trials aiming to improve upon BCG effectiveness. Host-directed therapies that boost immune responses are also being investigated.

Digital health innovations include smartphone-based treatment monitoring and artificial intelligence for chest X-ray interpretation. ClinicalTrials.gov lists numerous ongoing TB studies, including trials of new drug combinations and treatment duration studies.

Frequently asked questions

Is TB contagious, and when am I no longer infectious?

Only active pulmonary TB is contagious, spread through airborne droplets. Most patients become non-infectious after 2-3 weeks of appropriate treatment, though this should be confirmed by healthcare providers.

What’s the difference between latent and active TB?

Latent TB means you’re infected but the bacteria are dormant and cause no symptoms. You’re not contagious with latent TB. Active TB causes symptoms and can be contagious if it affects the lungs.

Can I develop TB more than once?

Yes, TB reinfection can occur, especially in areas with high TB transmission or in people with weakened immune systems. Previous TB infection doesn’t provide complete immunity.

Why does TB treatment take so long?

TB bacteria grow slowly and can become dormant, requiring prolonged treatment to ensure all bacteria are killed and prevent development of drug resistance.

Can TB be completely cured?

Yes, with appropriate treatment completion, drug-sensitive TB can be completely cured in over 95% of cases. Even drug-resistant TB can often be cured with proper treatment.

Support and resources

International organizations:
– World Health Organization TB Programme (who.int/health-topics/tuberculosis)
– Stop TB Partnership (stoptb.org)
– Global Alliance for TB Drug Development (tballiance.org)
– International Union Against Tuberculosis and Lung Disease (theunion.org)

Patient support:
– TB Alert (tbalert.org)
– National TB Controllers Association (tbcontrollers.org)
– Treatment Action Group (treatmentactiongroup.org)

Related conditions

Pneumonia – Another infectious lung disease that can cause similar symptoms but typically has a more acute onset than TB.

Lung cancer – May present with chronic cough and weight loss, requiring differentiation from pulmonary TB through imaging and biopsy.

Sarcoidosis – An inflammatory disease that can mimic TB radiologically and histologically, requiring careful diagnostic workup.

Histoplasmosis – A fungal infection that can cause similar pulmonary symptoms and radiological findings to TB.

Chronic obstructive pulmonary disease – May develop as a long-term complication of pulmonary TB or increase susceptibility to TB infection.

Sources: Orphanet (orpha.net), OMIM, GeneReviews (NCBI), WHO ICD-11, UpToDate, relevant EULAR/ACR/WHO guidelines. This article is for informational purposes only and does not constitute medical advice. Content licensed under CC BY 4.0.

Sources: Orphanet (orpha.net), OMIM, GeneReviews (NCBI), WHO ICD-11, EULAR/ACR guidelines. Schema.org MedicalCondition structured data included.