What Is Tuberculosis

What Is Tuberculosis

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. The bacteria usually enter the body through the respiratory system after a person inhales infectious particles released into the air by someone with active TB of the lungs or throat.

TB infection does not always immediately cause illness. In some people, the immune system controls the bacteria, resulting in latent TB infection. In others, the bacteria multiply and cause active TB disease.

Latent TB vs. Active TB

Latent TB infection means TB bacteria are present in the body but are inactive. A person with latent TB generally has no symptoms and does not normally transmit TB to other people.

Active TB disease occurs when the bacteria become active and multiply. Pulmonary TB can cause coughing and other respiratory symptoms and may be contagious.

Without appropriate treatment, latent TB can sometimes progress to active disease.

What Causes Tuberculosis?

The primary cause of TB is infection with Mycobacterium tuberculosis.

TB is mainly transmitted through the air. When a person with infectious pulmonary TB coughs, sneezes, speaks, or sings, bacteria-containing particles can enter the surrounding air. Another person may become infected after inhaling these particles.

The likelihood of transmission can be affected by factors such as:

• How infectious the person with TB is
• How long others are exposed
• Indoor ventilation
• Crowding
• Whether effective TB treatment has begun

TB is not normally spread through casual contact such as shaking hands, sharing food, or touching ordinary household objects.

Who Is at Greater Risk?

Anyone can develop TB, but certain circumstances increase the risk of infection or progression from latent infection to active disease.

Risk factors include:

• Close contact with someone who has infectious TB
• Living or working in crowded conditions
• Poorly ventilated environments
• A weakened immune system
• Diabetes
• Malnutrition
• Smoking
• Previous untreated TB infection
• Living in or frequently travelling to regions where TB is common

Symptoms of Tuberculosis

TB symptoms can develop slowly. Some people may initially have few symptoms or mistake them for another illness.

Common Symptoms of Pulmonary TB

Symptoms can include:

• Persistent cough
• Cough lasting three weeks or longer
• Chest pain
• Coughing up sputum
• Coughing up blood
• Fever
• Night sweats
• Unexplained weight loss
• Loss of appetite
• Fatigue and weakness

The presence of these symptoms does not automatically mean someone has TB. Several other infections and medical conditions can cause similar symptoms, so diagnostic testing is important.

Symptoms of TB Outside the Lungs

TB can occur in organs other than the lungs, a condition sometimes called extrapulmonary TB.

Symptoms vary according to the affected organ.

For example:

• Lymph nodes: persistent swelling or enlarged lymph nodes
• Bones and joints: pain, swelling, or reduced movement
• Spine: persistent back pain or neurological problems
• Kidneys: urinary symptoms or blood in the urine
• Brain: severe headache, confusion, vomiting, seizures, or other neurological symptoms

TB involving the brain, spinal cord, or other critical organs requires prompt medical evaluation.

How Is Tuberculosis Diagnosed?

Diagnosing TB usually involves a combination of medical history, physical examination, laboratory testing, and imaging.

TB Infection Tests

Two commonly used tests for TB infection are:

Tuberculin skin test (TST)
A small amount of testing material is placed into the skin. The reaction is examined after the recommended period.

Interferon-gamma release assay (IGRA)
This is a blood test that measures the immune response to TB bacteria.

These tests can identify TB infection but generally cannot determine on their own whether someone has latent TB or active TB disease.

Tests for Active TB

If active TB is suspected, doctors may use:

• Chest X-ray
• CT imaging when appropriate
• Sputum microscopy
• Molecular TB tests
• TB culture
• Drug-susceptibility testing

Molecular testing can help identify TB bacteria and, depending on the test, provide information about resistance to particular medicines.

Why Drug-Resistance Testing Matters

TB bacteria can become resistant to medicines. Testing can help doctors determine which drugs are likely to work.

This is especially important when multidrug-resistant TB is suspected.

Treatment for Tuberculosis

TB is treated with antibiotics. Active TB generally requires multiple medicines taken together to kill the bacteria effectively and reduce the risk of resistance.

For drug-susceptible pulmonary TB, commonly used medicines include:

• Rifampicin (rifampin)
• Isoniazid
• Pyrazinamide
• Ethambutol

Treatment usually consists of an initial phase followed by a continuation phase. The exact regimen and duration depend on the patient's TB type, laboratory results, drug susceptibility, other health conditions, and applicable treatment guidelines.

Why Completing Treatment Is So Important

A person may begin feeling better before all TB bacteria have been eliminated.

Stopping treatment prematurely can allow surviving bacteria to multiply. It can also contribute to the development of drug-resistant TB.

For this reason:

Do not stop TB medication simply because symptoms have improved.

Patients should take their medicines according to their healthcare professional's instructions and report significant side effects promptly.

Drug-Resistant TB

Drug-resistant TB occurs when TB bacteria no longer respond adequately to medicines that would normally treat the infection.

Multidrug-resistant TB (MDR-TB) is one important form of drug-resistant TB. Other resistance patterns can also occur.

Treatment is based on laboratory testing and may require specialised combinations of medicines. Drug-resistant TB can be more complicated to treat than drug-susceptible TB.

Can Tuberculosis Be Prevented?

Several measures can reduce the risk of TB.

1. Early Diagnosis

Finding active TB quickly allows treatment to begin sooner and can reduce the opportunity for transmission.

2. Treating Latent TB

People with TB infection who are at significant risk of developing active disease may be offered preventive treatment after a medical assessment.

3. Good Ventilation

Fresh-air ventilation can reduce the concentration of infectious particles in indoor environments.

4. Infection-Control Measures

Healthcare facilities may use specialised respiratory precautions when caring for people with suspected or confirmed infectious TB.

5. BCG Vaccination

The BCG vaccine is used in many countries where TB is common. It is particularly effective at protecting children against severe forms of TB, although its protection against pulmonary TB varies.

Tuberculosis and Children

Children can develop TB, and young children are particularly vulnerable to severe forms of the disease.

Possible symptoms can include:

• Persistent fever
• Poor appetite
• Weight loss or failure to gain weight
• Persistent cough
• Weakness or reduced activity
• Enlarged lymph nodes

Because symptoms can be less obvious in children, medical evaluation is important after significant exposure to active TB.

Tuberculosis During Pregnancy

TB can occur during pregnancy and requires appropriate medical management.

Pregnant people with possible TB symptoms or known exposure should seek medical advice promptly. Doctors can select diagnostic tests and treatment options based on the individual's circumstances.

Untreated active TB can pose significant risks to both the pregnant person and the developing baby, so suspected disease should not simply be ignored because of pregnancy.

Is Tuberculosis Curable?

Yes. TB is generally curable when the appropriate medicines are taken correctly, and the full treatment course is completed.

However, treatment success depends on factors such as:

• Whether the TB is drug-susceptible or drug-resistant
• Correct diagnosis
• Appropriate medication selection
• Consistent adherence to treatment
• Management of other medical conditions
• Monitoring for medication side effects

Drug-resistant TB may require more complex treatment.

When Should You See a Doctor?

Seek medical evaluation if you develop symptoms such as:

• A persistent cough
• Fever lasting several days or recurring
• Night sweats
• Unexplained weight loss
• Coughing up blood
• Persistent chest pain
• Unusual fatigue

Medical evaluation is particularly important after close contact with someone who has infectious TB.

Coughing up significant amounts of blood, severe breathing difficulty, confusion, seizures, or other serious neurological symptoms require urgent medical attention.

Frequently Asked Questions About Tuberculosis

Is TB contagious?

Active TB affecting the lungs or throat can be contagious because the bacteria can spread through the air. Latent TB infection does not normally spread to other people.

Can TB be completely cured?

Yes. Most drug-susceptible TB can be cured with the correct treatment and completion of the prescribed regimen. Drug-resistant TB requires specialised treatment.

How long does TB treatment take?

Treatment commonly lasts several months, but the exact duration depends on the type of TB, drug susceptibility, treatment regimen, and individual circumstances.

Can a person have TB without symptoms?

Yes. People with latent TB infection usually have no symptoms. Some people with active TB may also have relatively mild symptoms initially.

Can TB come back after treatment?

TB can recur, although completing appropriate treatment greatly reduces the risk. A new infection can also occur after successful treatment.

Is TB spread by sharing food?

TB is primarily transmitted through the air from people with infectious pulmonary or throat TB. It is not normally spread by sharing food or drinks.

Is there a vaccine for TB?

Yes. The BCG vaccine is used in many countries and provides important protection against severe TB in children. Its effectiveness against pulmonary TB varies.

Can TB affect organs other than the lungs?

Yes. TB can affect lymph nodes, bones, joints, kidneys, the spine, brain, and other organs.

Conclusion

Tuberculosis is a serious infectious disease, but it is preventable, treatable, and usually curable when it is diagnosed and managed appropriately.

Understanding the difference between latent TB infection and active TB disease is important. Persistent cough, fever, night sweats, unexplained weight loss, or coughing up blood should be evaluated by a doctor, particularly after possible exposure to TB.

Early diagnosis, appropriate treatment, drug-resistance testing when indicated, and completing the prescribed medication are central to controlling TB and protecting communities.

Important: This article is for general educational purposes and does not replace diagnosis or treatment from a qualified healthcare professional.