Tuberculosis (TB) is a highly contagious bacterial infection that primarily affects the lungs but can also spread to other parts of the body, such as the brain and spine. It is caused by a bacterium called Mycobacterium tuberculosis.

A person may develop TB after inhaling Mycobacterium tuberculosis bacteria, primarily through person-to-person transmission. TB is most contagious when it affects the lungs, but a person usually only becomes sick after close contact with someone who has active pulmonary TB. People with HIV/AIDS or other weakened immune systems are at a higher risk of contracting tuberculosis because their bodies have a harder time fighting the bacteria.

Types of Tuberculosis
A TB infection doesn’t always result in illness. There are several stages and forms of the disease:
Primary TB: This is the first stage of a TB infection. Your immune system may be able to fight off the bacteria, but sometimes it doesn’t destroy all of them, allowing the bacteria to continue multiplying.
Active TB: The bacteria multiply and make you sick. You can spread the disease to others. Around 90% of active TB cases in adults come from latent TB infections.
Latent TB: You have the bacteria in your body, but your immune system keeps them from spreading. You don’t have symptoms and are not contagious. However, the infection remains alive and could become active at any time.
Active TB Outside the Lungs: When TB spreads to other parts of the body, it is called extrapulmonary tuberculosis. Symptoms vary depending on which part of the body is affected.

A latent or active TB infection can also be drug-resistant, meaning certain medications may not work against the bacteria.

Causes
TB bacteria spread through the air, similar to how cold or flu viruses are transmitted. You can contract TB only if you come into contact with someone who has it. The bacterium Mycobacterium tuberculosis causes TB.

Risk Factors
• Weakened immune system
• Age
• Close contact with an infected person
• Health care workers
• Smoking
• Air pollution
• Malnutrition
• Prolonged use of tobacco or alcohol
• Having diabetes, kidney disease, or certain cancers
• HIV or other immune system-compromising conditions

Other medications that increase the risk of active TB include those taken to treat:
• Psoriasis
• Lupus
• Crohn’s disease
• Rheumatoid arthritis
• Cancer

Symptoms
General TB symptoms include:
• Weakness
• Fever
• Chills
• Weight loss
• Loss of appetite
• Night sweats
• Fatigue

Symptoms specific to TB in the lungs include:
• A cough lasting more than 3 weeks
• Chest pain
• Coughing up blood

TB symptoms can vary in teens, children, and babies:
• Teens: Symptoms are similar to those of adults.
• Children (ages 1-12): Weight loss and persistent fever.
• Babies: May experience vomiting, trouble feeding, or lethargy.

Diagnosis
• Physical exam
• Tuberculosis skin test (also known as the Mantoux tuberculin skin test)
• Tuberculosis blood test (interferon-gamma release assays, or IGRAs)
• Chest X-ray or CT scan
• AFB (Acid-Fast Bacillus) test
• Bronchoscopy

Treatment
Your treatment will depend on the type of infection:
Latent TB: If you have latent TB, your doctor will prescribe medications such as isoniazid, rifampin, or rifapentine, either alone or in combination, to prevent the infection from becoming active. You will need to take these medications for at least 3 months.
Active TB: Treatment usually involves a combination of ethambutol, isoniazid, pyrazinamide, and rifampin for 6 to 12 months.
Drug-resistant TB: Some strains of TB are resistant to antibiotics and require different treatments.

Tuberculosis Complications
If untreated, TB can lead to serious complications, such as:
• Lung damage
• Heart inflammation
• Liver and kidney problems
• Inflammation of tissues
• Joint damage
• Infection or damage to bones, the spinal cord, brain, or lymph nodes

Prevention
• Bacillus Calmette-Guerin (BCG) vaccine
• Wearing a mask to cover the mouth and ensuring proper ventilation in rooms
• Avoiding close contact with infected individuals
• Avoiding smoking and exposure to pollutants
• Maintaining a healthy lifestyle
• Seeking timely diagnosis and treatment
• Practicing environmental hygiene