UNDERSTANDING TUBERCULOSIS in children and adults

Tuberculosis was once the leading cause of death in the United States. Effective antibiotic regimens have dramatically decreased the number of cases nationwide, though resistant strains have emerged. While the risk for TB is greater in communities with lower socioeconomics, it is important that all communities remain vigilant.

Recommendations regarding risk factors and testing in both children and adults have changed. Understanding TB, the types of infection, how it is spread and how it is prevented can help equip parents with the knowledge to protect themselves and their children against a realistic and potentially dangerous infection.

Screening

Screening of individuals who may be at increased risk is a crucial aspect of TB prevention. The Mantoux test, which has been in use since the 1930s, is the best screening test. It is often referred to as a PPD because a Purified Protein Derivative of TB is injected under the skin. People who have active or latent infection will have a reaction. In the 1960s and 1970s, when TB rates were very high, universal testing of all children at regular intervals was required. This is no longer the recommendation.

The American Academy of Pediatrics (and the Centers for Disease Control, the American Thoracic Society and the Infectious Diseases Society of America) is now recommending “targeted tuberculin skin testing” or TST which means only testing the children who are at high risk.

Pediatricians (including your doctors at PHA) are using screening questionnaires (see below) and only testing children when risk factors are present. Studies have carefully evaluated and validated this method of screening.

Screening questionairres should include the following questions:

  1. Was your child born outside the United States?
  2. Has your child traveled outside the United States?
  3. Has your child been exposed to anyone with TB?
  4. Does your child have close contact with a person who has had a positive TB skin test result?
  5. Does your child spend time with anyone who has been in jail or a shelter, uses illegal drugs or has HIV?
  6. Has your child had raw milk or eaten unpasteurized cheese?
  7. Does your child have a household member who was born outside the United States?
  8. Does your child have a household member who has traveled outside the United States?

A child or adolescent should be tested by his or her physicianonly if more than one risk factor is present. The skin test (PPD) needs to be checked in 48 hours. If the skin in the testing area becomes raised and hard, further evaluation and treatment may be needed.

The physician should evaluate any reaction to the skin test. Treatment is very complex. Therapy is determined by the size of the reaction, evidence of active TB, and a patient’s general medical health. Even in the least complicated case — a positive skin test, no symptoms, and a negative chest x-ray, — 9 months of medicine is required. More specific information is available at the CDC website, www.cdc.gov/mmwr.

What is TB?

Specifically, tuberculosis is bacterial infection caused by Mycobacterium tuberculosis. The bacteria are almost always transmitted through an airborne route. An infected individual can spread the infection by coughing, sneezing, even just talking. When inhaled by another person, the bacteria enter the lungs and cause infection.

Difficulty in identifying and controlling TB results from not every infected person feeling sick. Many are infected for years, even decades, before they know. In most, the body is able to fight the bacteria and keep them from growing. The bacteria remain alive but inactive inside the body. This is a latent TB infection (LTBI). People with a latent infection have no symptoms. They do not feel sick and are not contagious. However, without identification and treatment these people may develop symptoms and become contagious.

When the body cannot control the infection, the bacteria begin to multiply; this is an active TB infection (ATBI). Active TB causes weakness, fatigue, fever, chills, sweating at night and weight loss. Because tuberculosis grows in the lungs, infected people experience bad coughing, chest pain and even coughing up blood. Those with active TB are contagious.

Three basic principles are used in the control of TB in the U.S. First is the critical task of diagnosing people with active infection. There are approximately 20,000 new cases of active TB in the U.S. each year. New York has the highest number of new cases in the country followed by California, Texas, Florida and Hawaii.

Identifying people exposed to an individual with active TB is the second step in control and prevention. Interestingly, by the time a person with active TB is diagnosed, 30% to 40% of people identified as close contacts have evidence of exposure and latent TB infection.

Once a person develops LTBI there is a 5% to 10% chance that active disease will develop. The risk for progression to active TB disease varies. Half the people who progress to active TB do so in the first two years. Acquisition of latent TB infection in infancy and early childhood (<5 years old) is a strong risk factor for progression. Medical conditions — including diabetes, kidney disease and immune system disorders (especially HIV) — also increase the risk for active TB. Thus, identifying people exposed to an individual with active TB is an important tool to detect additional cases of active TB and also identifies people in the early stages of latent TB, when the risk for progression is greatest.

Unfortunately, TB is a global problem. Poor conditions and lack of medical resources contribute to 8 million new diagnoses of active TB and 3 million deaths annually. It is estimated that 20% to 30% of the world’s population is infected with TB. But with careful screening, TB in the United States should be controlled and serious consequences prevented. Careful attention to risk factors and possible exposures will help to protect our children.