Tuberculosis (TB) latency involves infection with the bacteria that also cause active TB. However, people with TB latency do not have symptoms. Treatment for TB latency can help reduce the risk of developing active TB disease.
TB is a condition caused by Mycobacterium tuberculosis (M. tuberculosis), which is a type of bacteria. It often affects the lungs but can also attack many other organs. Some people who contract M. tuberculosis become sick and experience symptoms. Doctors call this active TB disease.
However, not everyone with M. tuberculosis develops symptoms or active disease. Doctors refer to people with M. tuberculosis who do not experience sickness or symptoms as having TB latency.
The article below describes TB latency, how it compares with active TB disease, and whether the condition needs treatment.
The bacteria that cause TB can live in the body without making someone unwell. TB latency means a person has an
If a person contracts M. tuberculosis but does not develop symptoms, this typically means that their body can fight the bacteria and keep the infection from growing. In this case, the bacteria may remain in the body but are inactive (do not cause active disease or illness).
Some people remain free of active TB disease for their lifetime. In other instances, without treatment, people may develop active TB disease at some point.
Latent TB infection and active TB disease differ. Someone with latent TB infection does not have symptoms of the disease.
An individual with active TB disease typically feels unwell. Symptoms can include:
- severe cough that lasts at least
- chest pain
- coughing up blood
- weight loss
- night sweats
Another key difference between latent TB infection and active TB disease is that TB disease can spread to other people. Latent TB is not contagious.
According to the World Health Organization, only a small percentage of people with TB infection develop active TB disease.
Without treatment, about
Latent TB infection
TB infection spreads from person to person through droplets containing M. tuberculosis that a person may breathe in. This is called airborne transmission.
For example, someone with active TB disease may cough or sneeze. The droplets become airborne, and an individual who inhales these droplets may develop the infection.
According to the American Lung Association, TB infection typically requires prolonged exposure. Latent TB infection happens when a person’s body stops the bacteria from growing and active disease does not develop.
Latent TB infection is not contagious. The condition
Learn about contagious TB.
Someone with a TB infection will experience a skin reaction to the test after several hours. Doctors measure the size of the skin reaction to determine a positive response, which indicates infection.
A positive test cannot distinguish between latent TB infection and active TB disease. Doctors need to perform further assessments, such as:
If a person is at an increased risk of developing TB, doctors may recommend screening and subsequent treatment if the test returns a positive result for latent TB infection. For example, a person with a weakened immune system is at
Treatment for latent TB can help stop the spread of TB and the development of active disease. Doctors can recommend different treatments for latent TB.
Medications a doctor may prescribe to treat latent TB infection include:
Depending on the medication, treatment may last
Here are some frequently asked questions about TB latency.
Is latent TB infection dangerous?
Latent TB infection itself is not dangerous as a person does not experience any symptoms. However, it
How does latent TB infection become active?
The bacteria that cause TB may remain in the body. They can activate in the future if something causes the immune system to weaken. The
TB latency, or latent TB infection, occurs when M. tuberculosis bacteria enter the body and remain inactive. Latent TB is not contagious and does not cause symptoms.
Doctors may recommend treatment for latent TB infection to help prevent it from developing into active TB disease. People with a compromised immune system are at an increased risk of latent TB becoming active TB disease.
It is best for a person to contact a doctor if they have concerns about TB. The doctor can order tests, such as a skin test, to confirm the diagnosis and advise on treatment options.