Tuberculosis, or TB, is an infectious illness caused by the bacterium Mycobacterium tuberculosis. It most often affects the lungs, although it can also involve other organs such as nerves, bones, and glands.

TB spreads when someone inhales air that contains TB bacteria from an infected person’s cough, sneeze, or saliva droplets. Even so, not everyone who acquires TB bacteria will develop symptoms. This stage is called latent TB, which means the bacteria are present but inactive.

How Latent TB Differs From Active TB

Unlike many bacterial infections, people who are newly infected with TB often do not show symptoms right away. Everyday Health outlines three broad phases:

• Primary infection happens when air carrying TB bacteria is inhaled. The bacteria enter through the mouth and nose, reach the lungs, and begin to multiply.

   

• Latent TB infection develops when the immune system keeps the bacteria in check. The germs remain in the body but are dormant or inactive.

   

• Active TB infection occurs if the immune defenses weaken and the dormant bacteria “wake up,” multiply, and start causing disease.

People commonly do not realize they have latent TB because this stage does not produce typical symptoms.

The CDC highlights several key differences between latent TB and active TB:

1. Latent TB

In this phase, a person is infected yet does not feel ill. Features of latent TB include:

• Feeling well without TB symptoms
• Unable to pass TB bacteria to other people
• Positive TB test with a normal chest X-ray and negative sputum results

Not everyone with latent TB will develop active disease. With a strong immune system, TB bacteria can remain dormant for a long time. If immunity becomes weak, the bacteria can become active, multiply, and progress to active TB.

2. Active TB

Active TB represents progression from latent infection when the immune system can no longer restrain bacterial growth. Signs of active TB include:

• Symptoms such as fever, a persistent cough with phlegm, and weight loss
• Ability to transmit TB bacteria to others
• Abnormal chest X-ray and a positive sputum test

If a doctor confirms active TB, treatment will be tailored to test results and clinical findings.

How Do Doctors Diagnose Latent TB?

Latent TB is rarely found by a routine physical exam because it usually causes no symptoms. Diagnosis relies on specific tests. The Mantoux skin test places a small amount of tuberculin under the skin of the forearm and is read several days later. Doctors may also order a chest X-ray and sputum testing.

People at higher risk for latent TB, such as those with weakened immunity, close contacts of someone with TB, or healthcare workers who care for TB patients, should be screened if they have been exposed.

Treatments for Latent TB

Although latent TB does not spread to others, treating it lowers the chance of progression to active disease. Common options include isoniazid, rifapentine, and rifampin. Depending on the regimen and individual factors, therapy can last about 4 to 9 months.

TB remains a serious infectious disease in many parts of the world, including Indonesia. With appropriate testing, treatment, and prevention, TB infection can be avoided or controlled. Seek medical care promptly if you have had close contact with a TB patient and notice a cough that does not improve.

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