TB transmission rates higher in children

A new study has shown that transmission rates among the close contacts of tuberculosis patients may be nearly twice as high if the index patient is a child.

Dr. Jonathan Roberts of the National Health Service in Bristol, the United Kingdom, led a team that conducted research using various databases, including Embase, Cinahl and Medline, according to

Roberts found that transmission rates from a child index were substantially higher to closer contacts, but then substantially lower to wider contacts. The researchers placed the weighted average for transmission from a pediatric patient at approximately 70 percent versus 40 percent in the adult population.

“This seems to be logical, given the nature of contact between children and adults in school settings,” the researchers said, reports. “In primary school settings where there is an adult source, the proportion of contacts screening positive is likely to be higher overall but similar between close and wider contacts.”

Roberts and his colleagues said that the transmission of TB is influenced by a variety of factors that include the virulence of the present organism, exposure to environmental factors and the patient’s Bacillus Calmette-Geuerin status.

Dr. Fernando Guerra, an editorial board member for the journal Infectious Diseases in Children, found his observations to be similar to the study’s findings. Guerra also noted the importance of environmental factors, particularly during the winter season when schools hold more activities indoors.

“On occasion, in a school setting when there is an exposure to an infected adult, and this has occurred over extended periods of time before the diagnosis of tuberculosis is confirmed, there is a greater likelihood of being more selective in the list of contacts that need to be screened,” Guerra said, reports.