Lung Disease & Respiratory Health Center

Screening People in Contact With Children May Help Prevent Tuberculosis

Dec. 3, 1999 (Atlanta) -- Screening the contacts of tuberculosis-positive children is effective in identifying others exposed to the disease, according to a report in a recent issue of the Pediatric Infectious Disease Journal. Experts say the data have important policy implications for preventing the spread of tuberculosis (TB).

TB is a chronic and serious infection caused by bacteria. It is an airborne infection, meaning it can be contracted just by being in the room of an infected person. Once the organism is acquired, a person will be 'positive' for TB but may not develop active TB for months or even years. Active TB infection causes severe chronic and recurrent lung disease and may also affect the brain, heart, and other parts of the body. It is very contagious, with the main symptom being a persistent cough. It is difficult to treat, requiring multiple medications for several months to years.

A skin test for TB has been used to detect or screen persons that carry the bacteria but may or may not have active TB. It requires observing the skin reaction to a small amount of TB extract. Persons with a positive skin test, but no symptoms of active infection, are placed on medications for several months to prevent developing active disease.

The study was conducted in New York City, where TB has undergone resurgence since the late 1980s. In response, public health officials have successfully focused on treating patients with active TB. Additionally, contact screening is conducted for children with a positive skin test. Contact screening involves screening any people who have had contact with a positive or actively infected person.

Researchers sought to determine if new cases of active TB could be found by screening the contacts of positive children up to 21 years of age. They selected nearly 190 households to participate in a two-year study of Hispanic residents originally from the Dominican Republic. Parents voluntarily identified a total of over 650 family members and close daily contacts who were then tested.

Although not one active case of TB was identified, more than 30% of the children's contacts had positive skin tests and were candidates for preventive therapy. Researchers also found that positive skin tests were strongly correlated with foreign birth, hosting foreign visitors, and Calmette-Guerin bacillus (BCG) immunizations administered in the Dominican Republic to help reduce the spread of TB.

"Contact screening was not effective in identifying undiagnosed active cases, but it was highly effective in identifying tuberculin-positive candidates for preventive therapy," says Karen Soren, MD, the study's lead researcher and assistant professor of pediatrics at Columbia University. "So the study has policy implications for tuberculosis prevention efforts in high-risk populations."

The chief investigator of a similar study agrees. "We studied contact screening in San Francisco with an Asian population and our findings were comparable," says Paul Sullam, MD, an infectious diseases specialist and associate professor of medicine at University of California, San Francisco. "Contact screening may well be a good strategy, but it's got to be cost-effective because resources are limited. As a next step, we ought to look at the potential cost savings of contact screening."