The Difference Between Latent and Active Tuberculosis

Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs but can also spread to other parts of the body. TB can exist in two forms- latent TB, where the bacteria remain inactive in the body and active TB, which leads to illness and can spread to others.

Understanding the latent TB and active TB difference is crucial for timely diagnosis, treatment, and prevention.

What is Active Tuberculosis?

Active tuberculosis or TB disease occurs when the Mycobacterium tuberculosis bacteria multiply and cause illness. With active TB, the germs keep reproducing in the body and cause tissue damage. Unlike latent TB, active TB is contagious and requires immediate medical attention.

Symptoms of Active Tuberculosis Infection

The symptoms of active tuberculosis depend on which part of the body is affected, but the most common signs include:

1. Persistent cough lasting more than three weeks
2. Coughing up blood or mucus
3. Chest pain
4. Unexplained weight loss
5. Fever and night sweats
6. Fatigue and weakness
7. Loss of appetite

If TB spreads beyond the lungs (extrapulmonary TB), it can affect other organs, such as the kidneys, brain, or spine, leading to additional complications.

What is Latent Tuberculosis?

Latent TB disease occurs when a person is infected with Mycobacterium tuberculosis but does not show any latent TB symptoms. The bacteria remain inactive in the body, and the individual does not feel sick or spread the infection to others.

Characteristics of Tuberculosis Latent

1. The immune system keeps the bacteria under control, preventing illness.
2. There are no visible symptoms of latent tuberculosis infection.
3. It is not contagious.
4. It can be detected through a TB skin test (Mantoux test) or a blood test.
5. If left untreated, latent TB can turn into active TB in the future

Risk Factors of Tuberculosis

Certain conditions and factors can weaken the immune system, increasing the risk of latent TB to active TB. These include:

1. HIV/AIDS
2. Diabetes
3. 3. Chronic kidney disease
4. Organ transplant
5. Cancer treatment (chemotherapy)
6. Malnutrition
7. Prolonged use of corticosteroids or other immunosuppressive drugs

How are Active TB and Latent TB Diagnosed?

Early and accurate diagnosis of tuberculosis is crucial for effective treatment and preventing its spread. Since latent and active tuberculosis present differently, doctors use specific tests to identify each condition.

Here’s how TB is diagnosed based on its stage and severity.

Latent TB Diagnosis

Since latent TB does not cause symptoms, it is diagnosed through:

1. Tuberculin Skin Test (TST/Mantoux test): A small amount of TB protein is injected into the skin, and the reaction is measured after 2-8 weeks.
2. Interferon-Gamma Release Assay (IGRA): A blood test that measures the immune response to TB bacteria.

Active TB Diagnosis 

A healthcare provider may diagnose active TB based on the following tests:

1. Chest X-ray to identify lung damage or infection.
2. Sputum test to examine mucus from the lungs for TB bacteria.
3. TB skin or TB blood test
4. Lab tests for drug resistance

How Can TB be Prevented?

Since TB spreads through the air, taking proactive measures can help reduce transmission and protect high-risk individuals.

1. Early Diagnosis: Identifying and treating latent TB early on prevents it from becoming active.
2. Hygiene Measures: Covering the mouth while coughing and maintaining good ventilation can reduce TB spread.
3. Avoiding Close Contact: Those with active TB should limit close contact until they are no longer contagious.

Conclusion

While latent TB remains dormant without symptoms, active TB can cause serious illness and spread to others if left untreated. Understanding the difference between latent TB and active TB is necessary for timely diagnosis, appropriate medication, and effective control.

If someone suspects exposure to TB or experiences symptoms, consult a healthcare professional for guidance and book a blood test at Dr. Lal Path Labs.

FAQs 

1. Can latent TB turn into active TB?

Yes, if the immune system weakens due to conditions such as HIV, diabetes, or malnutrition, latent TB can become active TB.

2. Can TB be completely cured?

Yes, latent and active TB can be cured with proper and timely treatment. It is essential to complete the full course of medication to prevent drug resistance.