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New data shed light on contact screening for TB patients

Roberts JR. Pediatr Infect Dis J. 2011;doi:10.1097/INF.0b013e31823378c9.

Transmission rates among close contacts of pediatric patients with tuberculosis may be twice as high compared with transmission rates if the index patient is an adult, according to results of a study published online.

Using various databases, including Embase, Cinahl and Medline, Jonathan R. Roberts, MPH, PhD, of the National Health Service in Bristol, United Kingdom, identified 29 studies that detailed cases of TB involving children aged 3 to 11 years. Of these studies, five reported on a pediatric index patient.

Transmission to close contacts was “substantially higher from a child index [than an adult index]; however, the risk of transmission to wider contacts was substantially lower,” the researchers said, adding that the weighted average for transmission from a pediatric patient was about 70% vs. 40% in the adult population.

“This seems to be logical, given the nature of contact between children and adults in school settings,” they said.

In background material contained within the report, Roberts and colleagues said transmission is influenced by a range of factors, including the virulence of the organism, exposure to environmental factors or Bacillus Calmette-Guerin status.

The researchers said their findings suggest that “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,” which may help hone in on those contacts that need to be screened after an index patient is identified.

Disclosure: The researchers report no relevant financial disclosures.

This serves to remind the reader of the importance of identifying cases of tuberculosis, and taking the appropriate measures for screening contacts, but recognizing the differences between children and adults in school settings. Our experience has been similar to what the authors have observed. I would note that the exposure to environmental factors is an important consideration, especially during the winter season when more activities take place within an indoor setting, and thus greater risk for sustained exposure, and transmission.

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.

Fernando A. Guerra, MD, MPH
Infectious Diseases in Children Editorial Board member

Disclosure: Dr. Guerra reports no relevant financial disclosures.

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