Tuberculosis — Symptoms, Causes & Treatment | MyMedicPlus

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis — a slow-growing, aerobic, acid-fast bacillus — transmitted via airborne droplet nuclei (1-5 microns in diameter) generated when an infectious person coughs, sneezes, sings, or speaks. Pulmonary TB (affecting the lungs) is the most common form, accounting for approximately 85% of all TB cases and the infectious form capable of sustained person-to-person transmission. Latent TB infection (LTBI) — where the bacteria are contained by the immune system in granulomata without causing active disease or symptoms — affects an estimated 2 billion people worldwide; approximately 10% of immunocompetent individuals with LTBI develop active TB disease during their lifetime, predominantly within the first 2 years of initial infection. Active TB disease causes illness and is transmissible to others. TB remains one of the top infectious disease killers globally, with 10 million new active cases and 1.5 million deaths annually. The WHO End TB Strategy targets a 90% reduction in TB deaths by 2030. Drug-resistant TB — MDR-TB (resistant to both rifampicin and isoniazid) and XDR-TB (additionally resistant to fluoroquinolones) — represents a growing global public health emergency, with approximately 410,000 MDR-TB cases annually. The disease is highly prevalent in South-East Asia, Africa, and Eastern Europe; the UK records approximately 4,600 cases annually.

M. tuberculosis is transmitted via droplet nuclei (1-5 microns diameter — small enough to remain suspended in the air for hours in poorly ventilated spaces). Prolonged close contact with an infectious smear-positive pulmonary TB case is typically required for transmission — brief contact rarely transmits TB. An infectious patient can infect 10-15 contacts per year in the absence of infection control measures. Risk factors for progression from latent TB infection to active disease: HIV co-infection (25-30-fold increased risk — the single most powerful risk factor; TB is the leading cause of death in HIV-positive individuals in Africa); TNF-alpha inhibitors (biologic therapies for rheumatoid arthritis, IBD, psoriasis — 2-10-fold increased risk — NICE mandates LTBI screening before starting); systemic corticosteroids at prednisolone equivalent above 15 mg/day; other immunosuppression (solid organ transplant, haematological malignancy, chemotherapy); malnutrition (BMI below 18.5); diabetes mellitus (2-3-fold increased risk); chronic renal failure (requiring dialysis); silicosis (occupational lung disease); tobacco smoking; alcohol dependence; overcrowding, homelessness, and incarceration; and prior inadequately treated TB. Geographic risk: South-East Asia (India, Indonesia, Pakistan — 44% of global burden), Sub-Saharan Africa, and Eastern Europe have the highest incidence rates.

Active pulmonary TB (the most common form): productive cough persisting beyond 2-3 weeks — the most common and important symptom (any cough lasting more than 3 weeks in a person from an endemic country or high-risk group should be investigated for TB); haemoptysis (blood-stained sputum — ranges from blood-streaking to massive haemoptysis from eroded pulmonary vessels); constitutional B symptoms: low-grade fever (typically 37.5-38.5 degrees, peaking in the afternoon — 'hectic fever'), drenching night sweats soaking clothing, progressive and unintentional weight loss (above 5% over 3 months) and anorexia; fatigue and malaise; and pleuritic chest pain (sharp, positional — from pleural involvement). Advanced pulmonary disease signs include: decreased breath sounds and bronchial breathing over consolidation; dullness to percussion from pleural effusion; and barrel chest from hyperinflation in chronic disease. Extrapulmonary TB (15% of cases — higher in HIV-positive individuals): TB lymphadenitis (the most common extrapulmonary site — unilateral or bilateral cervical and supraclavicular lymph node enlargement, initially firm and tender, later forming a fluctuant cold abscess or discharging sinus); TB meningitis (the most serious extrapulmonary form — subacute onset over days to weeks with headache, photophobia, and progressive neck stiffness; cranial nerve palsies — CN VI, VII; altered consciousness; and hydrocephalus); Pott's disease (spinal TB — thoracic vertebral body destruction causing back pain, progressive kyphosis, vertebral collapse, and potential spinal cord compression with neurological deficit); TB pericarditis (pericardial effusion causing exertional dyspnoea and tamponade); renal TB (sterile pyuria — pus cells in urine with negative standard culture; frequency, dysuria, haematuria); and miliary TB (haematogenous dissemination — multiple tiny 1-2 mm foci visible on chest X-ray as 'miliary pattern'; presents with fever, malaise, and hepatosplenomegaly; requires urgent treatment).

AFB (Acid-Fast Bacilli) sputum smear microscopy: rapid, identifies 50-60% of pulmonary TB. Sputum culture on Lowenstein-Jensen medium (gold standard, 6-8 weeks) or liquid MGIT (2-3 weeks). GeneXpert MTB/RIF (NAAT): rapid (2 hours), detects M. tuberculosis and rifampicin resistance simultaneously — WHO-recommended first test. Chest X-ray: upper lobe infiltrates, cavitation, hilar lymphadenopathy. IGRA (QuantiFERON-TB Gold) or Mantoux (TST) for latent TB. HIV testing for all TB patients. A systematic diagnostic approach that carefully combines a thorough clinical history, detailed physical examination findings, and appropriately targeted laboratory and imaging investigations is essential to accurately distinguish this condition from closely mimicking disorders and to guide safe and effective treatment selection. Early specialist referral — particularly when the diagnosis is uncertain or when initial treatments fail — optimises diagnostic accuracy and reduces unnecessary delays to effective management.

Active drug-sensitive TB: standard RIPE (RHZE) regimen — intensive phase (months 1-2): Rifampicin (R) + Isoniazid (H/INH) + Pyrazinamide (Z) + Ethambutol (E), all four drugs taken daily; continuation phase (months 3-6): Rifampicin (R) + Isoniazid (H) daily (total 6 months). Doses are weight-based: rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg, ethambutol 20 mg/kg. Pyridoxine (vitamin B6) 10-25 mg daily is co-prescribed with isoniazid to prevent peripheral neuropathy (isoniazid competitively inhibits pyridoxine-dependent pathways). Directly Observed Therapy (DOT): a public health nurse or trained community worker observes each dose being swallowed — the most effective strategy to prevent non-adherence and acquired drug resistance; recommended by WHO for all cases in high-burden settings and for non-adherent or homeless patients. Extended treatment duration is indicated for TB meningitis, spinal TB (9-12 months), and bone and joint TB (12 months). Adjunctive corticosteroids: dexamethasone (0.4 mg/kg/day tapering over 6-8 weeks) for TB meningitis (NEJM Thwaites trial — reduces mortality and neurological disability); prednisolone 60 mg/day tapering for TB pericarditis (reduces pericardial constriction risk). Latent TB infection (LTBI) treatment: isoniazid 6-9 months (6H or 9H); or 3 months daily isoniazid plus rifampicin (3HR — preferred in the UK); or 1 month daily isoniazid plus rifapentine (1HP — most convenient, very high completion rates). MDR-TB (resistant to both rifampicin and isoniazid): individualized regimens based on drug susceptibility testing (DST) — current WHO recommended shorter MDR-TB regimen (BPaLM): bedaquiline, pretomanid, linezolid, moxifloxacin for 6 months; longer regimens of 18-20 months may include bedaquiline, linezolid, clofazimine, and delamanid. XDR-TB requires specialist TB centre management.

Extensive cavitary pulmonary disease with permanent lung fibrosis, bronchiectasis, and chronic respiratory failure — particularly in delayed or inadequately treated cases. Massive haemoptysis (from erosion of a Rasmussen aneurysm within a cavity — life-threatening, requires bronchial artery embolisation or emergency surgery). Multidrug-resistant TB (MDR-TB — resistant to both rifampicin and isoniazid, the two most powerful first-line drugs): affects approximately 480,000 people annually; requires 18-24 month regimens with more toxic second-line drugs; treatment success rates of 50-60%, substantially lower than drug-sensitive TB. Extensively drug-resistant TB (XDR-TB — additionally resistant to fluoroquinolones): much harder to treat; requires specialist centre management with bedaquiline, linezolid, and pretomanid-based regimens. Extrapulmonary complications: TB meningitis (20-50% mortality and high neurological disability even with treatment), Pott's disease (spinal cord compression from vertebral TB), and pericardial constriction (from TB pericarditis causing haemodynamic compromise). TB-IRIS (immune reconstitution inflammatory syndrome) in HIV-positive patients: paradoxical worsening of TB symptoms within weeks of starting antiretroviral therapy as the reconstituted immune system mounts an amplified inflammatory response against residual mycobacterial antigens — managed with prednisolone. Drug-induced hepatotoxicity: isoniazid, pyrazinamide, and rifampicin all cause liver enzyme elevation — severe hepatotoxicity (ALT above 5x upper limit) requires temporary treatment suspension; regular LFT monitoring is mandatory.

BCG vaccination (Bacillus Calmette-Guerin) at birth in endemic countries — 70-80% effective against severe TB in children (meningitis, miliary TB). N95 respirators in healthcare settings. LTBI treatment: isoniazid 6-9 months (6H or 9H) or 3 months isoniazid + rifampicin (3HR) or 1 month daily rifapentine + isoniazid (1HP). Contact tracing and screening. Airborne isolation for infectious cases until sputum smear-negative on 3 consecutive specimens. Sustained lifestyle modifications — maintaining a healthy body weight through balanced diet and regular physical activity, avoiding tobacco smoking, limiting alcohol intake, and managing chronic conditions such as hypertension and diabetes — are foundational strategies for reducing the risk of this condition and its complications. Regular health screening in at-risk populations, rigorous adherence to prescribed preventive medications, and proactive monitoring of established risk factors are equally critical and complementary components of a comprehensive and effective long-term prevention strategy.

See your GP urgently (same week) or walk-in centre for assessment if you have: persistent cough lasting more than 3 weeks, especially with blood-stained sputum (haemoptysis), unexplained weight loss, profuse night sweats soaking clothing, or fever without an obvious cause — these are the classic symptoms of active pulmonary TB. TB is a notifiable disease in the UK and must be reported by the diagnosing clinician. Attend Emergency Department immediately for: massive haemoptysis (coughing up large volumes of bright red blood — TB erodes blood vessels) — airway protection and embolisation may be required; acute neurological symptoms (severe headache, neck stiffness, confusion, seizures) in a person with suspected or confirmed TB — TB meningitis requires emergency hospital admission and immediate treatment with rifampicin, isoniazid, pyrazinamide, and dexamethasone; severe breathlessness in a person with known TB — possible TB pericarditis with tamponade, pneumothorax, or miliary spread; signs of immune reconstitution inflammatory syndrome (IRIS) — paradoxical worsening of symptoms in HIV-positive patients after starting antiretroviral therapy alongside TB treatment requires urgent specialist review. If you are a contact of a confirmed TB case: attend your GP for contact tracing IGRA testing — latent TB infection can be treated with preventive therapy to eliminate the risk of developing active disease.