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
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
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."