Data from the World Health Organization (WHO) found that there are over 10 million tuberculosis patients worldwide, and it is estimated that 1 in 4 people globally have latent tuberculosis infection without knowing it. Even more frightening is that Thailand is among the 14 countries with severe tuberculosis. Therefore, latent tuberculosis infection is something we all need to be cautious about!
What is latent tuberculosis?
Latent tuberculosis means that we have been infected with tuberculosis bacteria, but the bacteria are hidden inside the body like a time bomb waiting to show symptoms when the body becomes weak. The nature of tuberculosis has a relatively long incubation period, which can take weeks, months, or in some cases, years before symptoms appear. Being infected but not showing symptoms is called latent tuberculosis (Latent TB).
Latent tuberculosis, although asymptomatic, is still serious!
Although latent tuberculosis does not show symptoms and cannot spread to others, several epidemiological studies in the United States have found that 5-10% of people with latent tuberculosis infection and normal immunity will develop active tuberculosis within 2-5 years after the initial infection. This excludes immunocompromised groups, who have a 21 times higher chance of progressing from latent tuberculosis to active tuberculosis.
How to know if latent tuberculosis is in your body?
There are 2 ways to test for latent tuberculosis infection:
1. Tuberculin skin test, which involves injecting a protein extract from the tuberculosis bacteria called PPD (Purified Protein Derivative) in a dose of 0.1 milliliters into the skin of the forearm. After 48 to 72 hours, the size of the raised area at the injection site is measured.
2. Interferon-gamma release assays (IGRAs), a blood test that measures the level of Interferon-gamma (IFN-γ), which increases when tuberculosis infection is present in the body. This test helps reduce false-positive results and is included in standard health check-up packages.
Therefore, to be aware of “latent tuberculosis,” regular health check-ups can help.
Are you at risk of latent tuberculosis?
If asked who is at risk of latent tuberculosis, the answer is “everyone,” especially those who
- Have close contact with tuberculosis patients
- Travel to crowded or densely populated areas
- Have underlying diseases that affect the immune system
Can latent tuberculosis be treated?
If Interferon-gamma (IFN-γ) is detected, the main treatment approaches are divided into 2:
- For people with normal immunity: doctors will consider close monitoring of symptoms.
- For immunocompromised individuals or those with a history of tuberculosis: doctors will consider using medication to inhibit bacterial replication to reduce the chance of developing active tuberculosis. This requires patient cooperation to take medication regularly and continuously as prescribed.
How to take care of yourself to reduce the risk of latent tuberculosis
- Avoid close contact with tuberculosis patients
- Wear a mask when traveling to crowded places
- Wash hands regularly after touching shared items
- Exercise to boost immunity
- Have regular health check-ups at least once a year to monitor lung function and screen for latent tuberculosis risk
Dr. Wichai Boonsrangsuk
Pulmonologist and Critical Respiratory Care Specialist
Internal Medicine Center, Phyathai 3 Hospital
