Tuberculosis (TB) — Symptoms, Diagnosis and Treatment

A persistent cough that just won't go away is one of the most common reasons patients walk into my clinic, and in Pakistan, tuberculosis is always on my list of possible causes.

Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. It usually attacks the lungs, but it can affect almost any organ. The good news is that TB is curable when it is diagnosed early and treated properly.

How does TB spread?

TB spreads through the air. When a person with active pulmonary TB coughs, sneezes, or speaks, they release tiny droplet nuclei containing the bacteria, and another person can inhale them. It is not spread by shaking hands, sharing utensils, or touching surfaces.

Not everyone who inhales the bacteria becomes sick. Many people develop latent TB, where the bacteria stay dormant, cause no symptoms, and are not contagious. Only active disease spreads to others. The risk of progressing from latent to active TB is higher in people with HIV, diabetes, malnutrition, or those on immunosuppressive drugs.

Symptoms of tuberculosis

Pulmonary TB

Pulmonary TB is the most common form. I suspect it when a patient has a cough lasting more than two to three weeks, along with:

• Sputum production, sometimes streaked with blood (hemoptysis)
• Low-grade evening fever and night sweats
• Unintentional weight loss and loss of appetite
• Fatigue and chest pain

Extrapulmonary TB

When the bacteria spread beyond the lungs, symptoms depend on the organ involved. Common sites include:

• Lymph nodes: painless neck swelling, the most common extrapulmonary form
• Pleura: pleural effusion with chest pain and breathlessness
• Spine and bones: back pain and deformity (Pott disease)
• Brain: TB meningitis, with headache, vomiting, and altered consciousness
• Abdomen and kidneys: abdominal pain, ascites, or sterile pyuria

How is TB diagnosed?

Diagnosis combines clinical suspicion with laboratory and imaging tests. The three I rely on most are:

Sputum smear and culture

Sputum is stained for acid-fast bacilli (AFB) under the microscope. It is cheap and quick, but not very sensitive. Culture is more accurate and allows drug-susceptibility testing, though results take weeks.

GeneXpert (Xpert MTB/RIF)

GeneXpert is a rapid molecular test that detects the DNA of M. tuberculosis and, at the same time, resistance to rifampicin. Results are ready in about two hours, and the World Health Organization recommends it as the initial diagnostic test for people with suspected TB.

Chest X-ray (CXR)

A chest X-ray typically shows upper-lobe infiltrates, cavitation, or hilar lymphadenopathy. CXR is a valuable screening tool, but it cannot confirm TB on its own, so I always pair it with a microbiological test.

Treatment: the anti-TB drug regimen

Drug-sensitive TB is treated for six months with four first-line anti-TB drugs:

• Intensive phase (2 months): isoniazid, rifampicin, pyrazinamide, and ethambutol
• Continuation phase (4 months): isoniazid and rifampicin

Treatment is delivered under DOTS (Directly Observed Treatment, Short-course), where a health worker or trained supporter watches the patient take each dose. This improves adherence and reduces the risk of drug resistance. Pyridoxine (vitamin B6) is usually added to prevent isoniazid-related neuropathy.

Patients should be monitored for side effects, especially hepatotoxicity (jaundice, nausea, dark urine) and visual changes with ethambutol. Some forms, such as TB meningitis and bone TB, need longer courses. Drug-resistant TB requires a specialized regimen under expert supervision.

The most important message I give every patient: even when you start feeling better after a few weeks, do not stop the medicines early. Incomplete treatment is the main driver of drug-resistant TB.