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Ask the Doctor: Tuberculosis

Updated: May 16, 2023

This article is co-written with Dr. Cecilia Paz Cruz-Ram, MD FPCOM, or Dr Z for short, our resident Medical Director of Doctor Anywhere Philippines.


March 24 is World Tuberculosis Day, a day to educate ourselves about the impact of Tuberculosis (TB) around the world. TB is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidneys, spine, and brain. Not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB infection (LTBI) and TB disease. If not treated properly, TB disease can be fatal.

What are the signs and symptoms of TB?

Symptoms of TB disease depend on where in the body the TB bacteria are growing. TB bacteria usually grow in the lungs (pulmonary TB). TB disease in the lungs may cause symptoms such as a bad cough that lasts 3 weeks or longer, pain in the chest, and coughing up blood or sputum (phlegm from deep inside the lungs).

Other symptoms of TB disease are weakness or fatigue, weight loss, loss of appetite, chills, fever, and sweating at night. Symptoms of TB disease in other parts of the body depend on the area affected. People who have latent TB infection do not feel sick, do not have any symptoms, and cannot spread TB to others.

How does TB spread?

TB bacteria are spread through the air from one person to another. The TB bacteria are put into the air when a person with TB disease of the lungs or throat coughs, speaks or sings. People nearby may breathe in these bacteria and become infected. TB is not spread by shaking someone’s hand, sharing food or drink, touching bed linens or toilet seats, sharing toothbrushes, and kissing.

When a person breathes in TB bacteria, the bacteria can settle in the lungs and begin to grow. From there, they can move through the blood to other parts of the body, such as the kidney, spine, and brain.

TB disease in the lungs or throat can be infectious. This means that the bacteria can be spread to other people. TB in other parts of the body, such as the kidney or spine, is usually not infectious.

People with TB disease are most likely to spread it to people they spend time with every day. This includes family members, friends, and coworkers or schoolmates.

Who is most at risk of contracting TB?

Some people develop TB disease soon after becoming infected (within weeks) before their immune system can fight the TB bacteria. Other people may get sick years later when their immune system becomes weak due to other reasons.

Overall, about 5 to 10% of infected persons who do not receive treatment for latent TB infection will develop TB disease at some point in their lives.

Generally, persons at high risk for developing TB disease fall into two categories:

1. Persons who have been recently infected with TB bacteria, including:

  • Close contacts of a person with infectious TB disease

  • Persons who have immigrated from areas of the world with high rates of TB

  • Children less than 5 years of age who have a positive TB test

  • Groups with high rates of TB transmission, such as homeless persons, injection drug users, and persons with HIV infection

  • Persons who work or reside with people who are at high risk for TB in facilities or institutions such as hospitals, homeless shelters, correctional facilities, nursing homes, and residential homes for those with HIV

2. Persons with medical conditions that weaken the immune system

Babies and young children often have weak immune systems. Other people can have weak immune systems, too, especially people with any of these conditions:

  • HIV infection (the virus that causes AIDS)

  • Substance abuse

  • Silicosis

  • Diabetes mellitus

  • Severe kidney disease

  • Low body weight

  • Organ transplants

  • Head and neck cancer

  • Medical treatments such as corticosteroids or organ transplant

  • Specialized treatment for rheumatoid arthritis or Crohn’s disease

Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. It is often given to infants and small children.

How to prevent Latent TB infection from progressing to TB disease?

Many people who have latent TB infection never develop TB disease. But some people who have latent TB infection are more likely to develop TB disease than others. Those at high risk for developing TB disease include:

  • People with HIV infection

  • People who became infected with TB bacteria in the last 2 years

  • Babies and young children

  • People who inject illegal drugs

  • People who are sick with other diseases that weaken the immune system

  • Elderly people

  • People who were not treated correctly for TB in the past

What should I do if I’ve been exposed to TB?

If you have latent TB infection and you are in one of these high-risk groups, you should take medicine to keep from developing TB disease. There are several treatment options for latent TB infection. You and your healthcare provider can decide which treatment is best for you. If you take your medicine as instructed, it can keep you from developing TB disease. Because there are fewer bacteria, treatment for latent TB infection is much easier than treatment for TB disease. A person with TB disease has a large amount of TB bacteria in the body. Several drugs would be needed to treat TB disease.

Have questions about TB or other symptoms of respiratory infection? Speak to a licensed doctor online within minutes on the Doctor Anywhere app.


Disclaimer: Doctor Anywhere disclaims any liability or responsibility for the consequences of any actions taken in reliance on the health advisory or safety tips. The health-related materials contained herein are not intended to establish policy, procedure, or standard of care.

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