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Tuberculosis Symptoms, Causes & Risk Factors

What Are the Symptoms of TB?

A person with TB infection will have no symptoms. A person with active TB disease may have any or all of the following symptoms:

  • A persistent cough
  • Constant fatigue
  • Weight loss
  • Loss of appetite
  • Fever
  • Coughing up blood
  • Night sweats

These symptoms can also occur with other diseases so it is important to see a healthcare provider and to let them find out if you have TB. A person with TB disease may feel perfectly healthy or may only have a cough from time to time. If you think you have been exposed to TB, get a TB test.

What Causes TB

Tuberculosis is an infection caused by bacteria. It's spread through the air—when an infected person coughs, sneezes, laughs, etc. However, it is not easy to become infected with tuberculosis. Usually, a person has to be close to someone with TB disease for a long period of time. TB is usually spread between family members, close friends, and people who work or live together. TB is spread most easily in closed spaces over a long period of time.

Most cases of active TB result from the activation of latent TB infections or old infections in people with impaired immune systems. People with clinically active TB will often but not always display symptoms and can spread the disease to others.

What Are the Risk Factors of TB?

The chances of getting infected by the TB germ are highest for people that are in close contact with others who are infected. This includes:

  • Family and friends of a person with infectious TB disease
  • People from parts of the world with high rates of TB, including India and parts of Asian and Africa. 
  • People in groups with high rates of TB transmission, including the homeless persons, injection drug users, and people living with HIV infection
  • People who work or reside in facilities or institutions that house people who are at high risk for TB such as hospitals, homeless shelters, correctional facilities, nursing homes, and residential homes for those with HIV

Not everyone who is infected with the TB germ (latent TB) develops clinically active TB disease. People at highest risk for developing active TB disease are those with a weak immune system, including:

  • Babies and young children, whose immune systems have not matured
  • People with chronic conditions such as diabetes or kidney disease
  • People with HIV/AIDS
  • Organ transplant recipients
  • Cancer patients undergoing chemotherapy
  • People receiving certain specialized treatments for autoimmune disorders such as rheumatoid arthritis or Crohn's disease

Preventing Tuberculosis

If you have become infected with TB, but do not have active TB disease, you may get preventive therapy. This treatment kills germs that are not doing any damage right now, but could so do in the future. The most common preventive therapy is a daily dose of the medicine isoniazid (INH) for 6 to 9 months.

If you take your medicine as instructed by your healthcare provider, it can keep you from developing active TB disease.

There is a vaccine against TB called BCG, or bacillus Calmette-Guerin. It is used in many foreign countries where TB is more common. However, it is not used very often in the United States because the chances of being infected with TB in the U.S. is low. It can also make TB skin tests less accurate. Recent evidence has shown that BCG is effective at reducing the incidence of TB in children by about half in populations with a high prevalence of active TB but is much less effective in adults.

When to See Your Doctor

A person who suspects that they may have TB should get tested by and notify their doctor or health department.

Learn more about diagnosing and treating TB.

    Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel. Last reviewed November 21, 2018.

    Page Last Updated: December 13, 2018

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