Tuberculosis

Tuberculosis, or TB, is an infectious disease caused by Mycobacterium tuberculosis. It most often affects the lungs, but it can also involve other parts of the body. TB spreads through the air when a person with active lung or throat TB coughs, speaks, sings, or sneezes. Because of this, prolonged indoor exposure increases the risk of transmission. ^[1][2]

A key distinction in TB is the difference between inactive (latent) infection and active disease. In latent TB, the bacteria remain in the body but do not cause symptoms and are not spread to others. In active TB disease, the bacteria multiply, symptoms appear, and transmission may occur if the lungs or airway are involved. This distinction is central to both public health and treatment decisions. ^[2][3][4]

Symptoms of active pulmonary tuberculosis may include a cough lasting weeks, coughing up blood, chest pain, fever, night sweats, fatigue, weight loss, and loss of appetite. When TB affects organs outside the lungs, symptoms depend on the involved site. Because these symptoms can overlap with many other illnesses, diagnosis requires medical evaluation rather than self-diagnosis. ^[1][2]

Diagnosis may involve a skin test or blood test to identify TB infection, as well as chest imaging and sputum testing to determine whether active disease is present. A positive infection test alone does not necessarily mean that the person has active contagious TB. Clinicians interpret test results together with symptoms, examination findings, and imaging. ^[1][2][3]

Treatment for active tuberculosis requires multiple antibiotics taken for a prolonged period. Careful adherence is essential because incomplete treatment can lead to treatment failure, ongoing transmission, or drug resistance. Latent TB can also be treated to reduce the risk of progression to active disease. The exact regimen depends on age, drug susceptibility, comorbidities, and local guidance. ^[1][3][4]

Some people are at higher risk of progressing from latent infection to active disease, including those with weakened immunity, certain chronic illnesses, or recent exposure to an infectious case. For these individuals, screening and preventive treatment can be particularly important. ^[2][3][4]

Urgent medical evaluation is advisable if there is coughing up blood, marked shortness of breath, significant weight loss, persistent fever, or symptoms suggesting severe illness. TB is treatable, but delayed diagnosis may increase complications and the risk of spread to others. ^[1][2]