Tuberculosis

Symptoms and Causative Agent

Tuberculosis is a disease caused by the tuberculosis bacteria, Mycobacterium tuberculosis.

Symptoms of active tuberculosis infection include cough lasting several weeks, coughing up sputum (mucus) or blood, fever, night sweats, fever, and pain in the chest.

Some people may be infected with tuberculosis bacteria, but have no symptoms. This is called latent tuberculosis. Latent tuberculosis may lead to active disease. Some people with latent tuberculosis may never become ill.

Transmission

The tuberculosis bacteria are spread via infected respiratory droplets, such as those spread when ill people cough, sneeze, or even speak. An uninfected person may inhale infected droplets into her or his lungs and become infected.

People with latent tuberculosis infections do not spread tuberculosis bacteria to others around them.

Treatment and Care

Most cases of tuberculosis can be successfully treated. People with active tuberculosis disease are treated with antibiotics and other drugs that kill or control the tuberculosis bacteria. Treatment usually lasts several months.

People with latent tuberculosis can be treated with antibiotics to ensure they do not later become ill with active tuberculosis.

In recent years, some tuberculosis strains have become resistant to antibiotics. These cases are more difficult and expensive to treat, and treatment can have serious side effects. Because drug-resistant tuberculosis is extremely challenging to treat, preventing the condition is important. Prevention measures include ensuring that people with tuberculosis take all the medication prescribed to them, and that they are treated with the correct medication.

Complications and Mortality

Though the route of tuberculosis infection is respiratory, and the main symptoms are usually respiratory, tuberculosis bacteria can spread to and infect other parts of the body, such as the bones and brain.

Untreated active tuberculosis disease can be fatal. About 3% of people with untreated TB will die. This figure is much higher, however, when a person also has human immunodeficiency virus (HIV) infection. About 18% of people with active TB infection and HIV infection may die.

Active TB infection is more deadly for young children. They are more likely to have serious complications from TB, such as TB meningitis (infection of the lining surrounding the brain).

In 2014, 9.6 million people became ill with tuberculosis. About 1.5 million people, including about 140,000 children, died from tuberculosis. About one-third of the world’s population has latent tuberculosis.

Available Vaccines and Vaccination Campaigns

The Bacille Calmette–Guérin (BCG) vaccine is used as part of national vaccination programs in countries with many cases of TB. The vaccine does not protect children from pulmonary disease caused by TB bacteria, nor prevent latent TB infection from progressing to active disease. It prevents serious TB complications in children, such as TB meningitis. The vaccine is generally not used in adults, and the vaccine in children does not prevent spread of the disease.

The BCG vaccine has been in use since 1921. Many researchers are working to develop a more effective tuberculosis vaccine. The hope is to develop a vaccine that prevents infection with tuberculosis, which would reduce the burden of disease global and also reduce transmission of the TB bacteria.

Vaccination Recommendations

In countries with many cases of TB, the BCG vaccine is given to infants shortly after they are born. Infants with HIV infection are not recommended to get the vaccine.

In countries with very few cases of TB, infants may be recommended to take the vaccine if they are likely to be exposed to TB, such as by living in a home with an adult with active TB infection.

Sources

• Centers for Disease Control and Prevention. . Accessed 01/25/2018.
• Straetemans, M., Glaziou, P., Bierrenbach, A.L., Sismanidis, C., & van der Werf, M.J. Assessing tuberculosis case fatality ratio: a meta-analysis. PLoS One, 2011;6(6), e20755.
• World Health Organization. . Accessed 01/25/2018.
• WHO. . No. 4, 2004, 79. 25-40. Accessed 01/25/2018.
• WHO. . Accessed 01/25/2018.
• WHO. . Updated January 2018. Accessed 01/25/2018.
• WHO. . Accessed 01/25/2018.