Chest X-rays may not detect asymptomatic TB among household contacts: Lancet report

Commonly used chest X-rays, based on symptoms, are inadequate to detect asymptomatic tuberculosis (TB) infection among household contacts, according to a study published in the journal The Lancet Global Health.

Researchers from the University of Cape Town, South Africa, conducted systematic screening with universal sputum microbiological testing of 979 household contacts of people with pulmonary tuberculosis in three South African communities.

They compared tuberculosis symptom (any duration) and chest radiograph (any abnormality indicative of active tuberculosis) screening approaches against a microbiological reference standard.

The team confirmed pulmonary tuberculosis in 5·2 per cent of household contacts, and 82·4 per cent of these reported no symptoms. Alarmingly, the chest radiographs were not able to detect 40 per cent of the cases.

“More than 80 per cent of confirmed people with tuberculosis among household contacts were asymptomatic; chest radiograph screening missed more than 40 per cent of these,” said corresponding author Dr Simon C Mendelsohn, South African Tuberculosis Vaccine Initiative, at the varsity.

“Community prevalence surveys reliant on symptom-based and chest radiograph-based approaches might substantially underestimate the prevalence of asymptomatic tuberculosis in endemic countries,” he added.