Tuberculosis (TB) is a chronic granulomatous infection caused by the acid-fast bacillus Mycobacterium tuberculosis. It primarily affects the lungs (pulmonary TB) but can affect any organ system (extrapulmonary TB). TB exists in two clinical states: latent TB infection (LTBI), affecting approximately one-quarter of the global population, and active TB disease, which is symptomatic and infectious. Treatment requires prolonged combination chemotherapy to prevent resistance. Despite being curable, TB remains a leading cause of death from infectious disease worldwide, particularly in resource-limited settings and among immunocompromised individuals.

Clinical Pearls:

• One of the oldest known human diseases, still causing 1.3 million deaths annually
• Latent TB affects 25% of global population; 5-10% lifetime risk of reactivation
• "Night sweat" hallmark: Drenching sweats requiring sheet changes
• Sterile pyuria suggests renal TB (mycobacteria don't grow on standard culture)
• Vitamin D deficiency is a major risk factor for reactivation

Red Flags:

• Massive haemoptysis: Rasmussen's aneurysm (erosion into pulmonary artery)
• Meningeal signs: TB meningitis (high mortality if untreated)
• Spinal tenderness: Pott's disease (vertebral TB)
• Addisonian crisis: Adrenal TB causing adrenal insufficiency
• Miliary TB: Widespread dissemination, high mortality

Non-Modifiable Risk Factors:

• Age: Infants and elderly at higher risk
• Genetics: Certain HLA types increase susceptibility
• Previous TB: History of TB increases reactivation risk
• Geographic origin: Born in or travel to high-prevalence areas

Modifiable Risk Factors:

• HIV infection: Strongest risk factor (20-30x increased risk)
• Immunosuppression: Organ transplant, anti-TNF therapy, steroids, chemotherapy
• Malnutrition: Protein-energy malnutrition, vitamin D deficiency
• Substance use: Alcohol, injection drug use
• Social factors: Homelessness, incarceration, overcrowding
• Diabetes: 2-3x increased risk
• Smoking: 2-3x increased risk

High-Risk Scenarios:

• Close contact: Household or workplace exposure to active TB
• Healthcare workers: Occupational exposure
• Prisoners: Overcrowding, high prevalence
• Refugees/migrants: From endemic areas

Protective Factors:

• BCG vaccination: Reduces risk of severe forms (miliary, meningitis) in children
• Good nutrition: Adequate protein, vitamin D
• HIV treatment: Antiretroviral therapy reduces TB risk
• Early diagnosis: Prompt treatment reduces transmission

"What is tuberculosis?" Tuberculosis (TB) is a bacterial infection that usually affects the lungs. It's caused by a germ called Mycobacterium tuberculosis. It's a serious infection that can make you very sick, but it's curable with the right treatment. TB spreads through the air when someone with active TB in their lungs coughs or sneezes.

"How did I get it?" TB spreads through tiny droplets in the air. If you were near someone with active TB who coughed, you could have breathed in the germs. Most people who get infected don't get sick right away - the germs stay "sleeping" in your body (latent TB). Later, if your immune system gets weaker, the germs can "wake up" and make you sick (active TB).

"What symptoms will I have?" The main symptoms are:

• A cough that won't go away (more than 3 weeks)
• Drenching night sweats (so bad you have to change your sheets)
• Losing weight without trying
• Feeling very tired all the time
• Fever, especially in the evenings
• Sometimes coughing up blood

"How is it diagnosed?" Your doctor will:

• Ask about your symptoms and if you've been around anyone with TB
• Test your sputum (phlegm) to look for the TB germs
• Do a chest X-ray to see if your lungs are affected
• Sometimes do a skin test or blood test to see if you've been exposed

"How is it treated?" TB needs special treatment with several strong antibiotics taken together for 6 months (or longer). You'll take:

• 4 different medicines for the first 2 months
• Then 2 medicines for the next 4 months

It's very important to take ALL your medicines, EVERY day, for the FULL time. If you stop early or miss doses, the TB can become resistant to the medicines, making it much harder to treat.

"Why so many medicines?" TB germs are very tough. Using just one medicine lets them learn to resist it. Using 4 medicines together makes sure we kill all the germs before they can become resistant. This is why you must finish the whole course.

"How long until I'm better?" Most people start feeling better within a few weeks of starting treatment. Your cough should get better, and you'll stop being infectious to others after about 2 weeks of treatment. However, you need to keep taking the medicines for the full 6 months to make sure all the germs are killed.

"Can I give it to others?" If you have active TB in your lungs, you can spread it to others by coughing. However, once you've been on treatment for 2 weeks, you're usually no longer infectious. Until then, you should:

• Stay home and avoid crowded places
• Cover your mouth when you cough
• Sleep in a separate room if possible
• Your doctor will tell you when it's safe to be around others

"What about side effects?" The medicines can cause side effects:

• Your urine and tears may turn orange/red (from rifampicin) - this is harmless
• You might feel sick to your stomach
• Your doctor will check your liver and eyes regularly
• Tell your doctor right away if you have vision problems, yellow skin, or severe side effects

"Will I be cured?" Yes! With proper treatment, more than 90% of people are completely cured. The key is:

• Taking all your medicines as prescribed
• Finishing the full course (don't stop early)
• Going to all your follow-up appointments
• Telling your doctor about any problems

"Can it come back?" If you finish your full treatment, it's very unlikely to come back (only 2-5% chance). If it does come back, it's usually because the treatment wasn't completed properly the first time. That's why it's so important to finish all your medicines.

"What if I miss doses?" Tell your doctor right away. Missing doses can let the TB germs become resistant to the medicines, making treatment much harder and longer. Your doctor may arrange for someone to watch you take your medicines (DOT - directly observed therapy) to make sure you don't miss any.