Study Reveals Limitations of Chest X-Rays in Detecting Asymptomatic Tuberculosis

A recent study published in The Lancet Global Health reveals that chest X-rays are inadequate for detecting asymptomatic tuberculosis among household contacts. Conducted by researchers from the University of Cape Town, the study found that a significant percentage of confirmed TB cases were asymptomatic, with chest X-rays missing 40% of these instances. The findings suggest that current screening methods may significantly underestimate the prevalence of TB in endemic areas, highlighting the need for improved diagnostic approaches. With millions of cases going undiagnosed, the challenge remains to identify and treat these individuals effectively.

By Narendra Chaudhary Oct 28, 2025, 16:53 IST

Inadequate Detection of Asymptomatic Tuberculosis

New Delhi, Oct 28: A recent study published in The Lancet Global Health highlights that standard chest X-rays, which are often used based on visible symptoms, fall short in identifying asymptomatic tuberculosis (TB) infections among household members of affected individuals.

Researchers from the University of Cape Town in South Africa undertook a comprehensive screening process involving universal sputum microbiological testing on 979 household contacts of patients with pulmonary tuberculosis across three communities in South Africa.

The study evaluated the effectiveness of symptom-based screening and chest radiographs against a microbiological reference standard.

Results indicated that 5.2% of the household contacts were confirmed to have pulmonary tuberculosis, with a staggering 82.4% of these individuals showing no symptoms. Alarmingly, chest X-rays failed to identify 40% of these cases.

Dr. Simon C Mendelsohn, the study's lead author from the South African Tuberculosis Vaccine Initiative, stated, “Over 80% of confirmed tuberculosis cases among household contacts were asymptomatic; chest radiograph screenings missed more than 40% of these cases.”

He further noted that community prevalence surveys that rely solely on symptom-based and chest radiograph methods may significantly underestimate the number of asymptomatic tuberculosis cases in regions where the disease is prevalent.

The World Health Organization (WHO) estimates that around 2.7 million, or 25%, of the 10.8 million individuals with tuberculosis globally were undiagnosed or untreated in 2023.

Identifying and treating these 'missing millions' is essential, yet the challenge lies in the fact that many remain asymptomatic.

The research team pointed out that more than half of the tuberculosis cases identified in community prevalence surveys are asymptomatic, occurring in individuals who do not exhibit or recognize typical symptoms such as cough, fever, night sweats, or weight loss.

In this study, asymptomatic tuberculosis cases among household contacts exhibited low bacterial loads and were linked to low serum C-reactive protein levels, similar to those of healthy individuals. In contrast, symptomatic tuberculosis cases were distinct from those in a comparator group of clinic attendees.

The sensitivity of chest radiograph screenings for asymptomatic tuberculosis was only 56.1%, while the sensitivity for combined symptom and chest radiograph screenings for all tuberculosis cases was slightly higher at 64.0%.

Dr. Mendelsohn concluded, “Our findings suggest that current symptom-based and chest radiograph screening methods are insufficient for community tuberculosis screening and do not align with the WHO's target product profile for tuberculosis screening tests, which requires a minimum sensitivity of 90% and specificity of 70%. National tuberculosis prevalence surveys that do not include universal sputum microbiological testing may significantly underestimate the prevalence of asymptomatic tuberculosis in high-burden countries.”