Epidemiology: Open Access
Open Access

Tuberculosis (TB) is a contagious illness caused by the bacteria Mycobacterium tuberculosis (Mtb). Tuberculosis affects the lungs in most cases, but it can also affect other regions of the body. The majority of infections are asymptomatic, which is known as latent TB. Around 10% of latent infections advance to active illness, which kills around half of individuals who are infected if left untreated.

Chronic cough with bloody mucus, fever, night sweats, and weight loss are all common signs of active tuberculosis. Because of the weight loss linked with the condition, it was previously referred to as consuming.

Patients with active tuberculosis in their lungs can spread the disease via the air by coughing, spitting, speaking, or sneezing People with latent TB do not pass the infection on to others. People with HIV/ AIDS and smokers are more likely to get active infection.

Chest X-rays, as well as microscopic inspection and culture of bodily fluids, are used to diagnose active tuberculosis. To detect latent TB, a Tuberculin Skin Test (TST) or blood tests are utilised.

Screening persons at high risk, early diagnosis and treatment of cases, and immunisation with the Bacillus Calmette-Guérin (BCG) vaccine are all part of TB prevention. Household, occupational, and social connections of patients with active TB are among those at high risk.

Multiple antibiotics must be used over a lengthy period of time to treat this infection. Antibiotic resistance is becoming more of an issue as the number of patients with multidrug-resistant TB rises.

Signs and symptoms

Tuberculosis may affect any region of the body, although the lungs are the most prevalent site of infection (known as pulmonary tuberculosis). Tuberculosis that originates outside of the lungs is known as extrapulmonary tuberculosis, however it can coexist alongside pulmonary tuberculosis.

Fever, chills, night sweats, lack of appetite, weight loss, and exhaustion are all common indications and symptoms. Nail clubbing is also a possibility.

Pulmonary

If TB becomes active, the illness usually affects the lungs (in about 90 percent of cases). Chest discomfort and a persistent cough with sputum are common symptoms.

People may cough up tiny quantities of blood sometimes, and in extremely rare situations, the infection may erode into the pulmonary artery or a Rasmussen's aneurysm, causing major haemorrhage. Tuberculosis can develop into a long-term infection that results in significant scarring in the upper lobes of the lungs.

Tuberculosis affects the higher lung lobes more commonly than the lower ones. The explanation for this disparity is unknown. It might be related to increased airflow or a lack of lymph drainage in the upper lungs.

Extrapulmonary

The infection spreads outside the lungs in 15-20 percent of active cases, creating various types of tuberculosis. Extrapulmonary tuberculosis refers to all of these conditions. People with a compromised immune system and small children are more likely to develop extrapulmonary tuberculosis. This occurs more than half of the time in HIV-positive patients.

The pleura (in tuberculous pleurisy), the central nervous system (in tuberculous meningitis), the lymphatic system (in scrofula of the neck), the genitourinary system (in urogenital tuberculosis), and the bones and extrapulmonary infection locations include joints (as in Pott disease of the spine) and the skin.