South Africa: Asymptomatic TB - a Hidden Challenge for TB Control

What the report says

AllAfrica, carrying a University of Cape Town report dated 30 July 2026, says UCT researchers have published findings in Nature Communications indicating that asymptomatic tuberculosis is both widespread and more biologically varied than current control strategies generally assume. The work was led by researchers at the South African Tuberculosis Vaccine Initiative, where scientists say the findings challenge screening and care approaches in South Africa, a country with a very high TB burden.

According to the report, national surveys have found that more than half of detected TB cases involve people who do not report typical symptoms such as cough, fever or weight loss, while some South African community screening studies have recorded asymptomatic proportions above 80%. The researchers found that existing diagnostic tools, largely designed around symptomatic disease, are weak when used for community-level detection of asymptomatic TB. They reported that current blood-based transcriptomic signatures performed below World Health Organization screening benchmarks when applied to asymptomatic cases.

The study identified two biologically distinct forms of asymptomatic TB using blood gene-expression and protein analysis. One group showed higher sputum bacterial loads, more chest X-ray abnormalities and stronger inflammation, making it more similar to symptomatic TB. The other appeared closer to early or controlled infection. The researchers say this suggests asymptomatic TB may sit on a spectrum, with some people potentially at greater risk of progression or transmission than others.

UCT researchers said future studies should test whether these subtypes predict different outcomes, infectiousness or treatment needs. The findings matter because people without symptoms may not seek care but can still have microbiologically confirmed TB, complicating South Africa’s efforts to detect infections earlier and reduce community transmission.