Take TB testing to the community to detect asymptomatic cases

To slow the spread of tuberculosis (TB) and enable early detection of infectious cases in South Africa and other high-burden countries, it’s crucial to take testing directly into the community. This will help people at high risk of infection, especially those who share a living space with TB patients and are asymptomatic.

According to a recent research study titled “Screening for asymptomatic tuberculosis among adults with household exposure to pulmonary tuberculosis: a prospective observational cohort study” – led by academics at the University of Cape Town (UCT) and published in The Lancet Global Health – testing these household contacts, even if they don’t feel unwell, is critical. This comes after research revealed that most TB cases detected among adults living with someone who has TB were silent at the time of screening.

The study’s lead author and a senior researcher at UCT’s South African Tuberculosis Vaccine Initiative (SATVI), Dr Simon Mendolsohn, said most people are only tested for TB after they present with symptoms such as a prolonged cough. And this needs to change.

“This new study shows that those approaches miss many people with TB.”

“National surveys also decide who gets a sputum test by first checking for symptoms or doing a chest X-ray. This new study shows that those approaches miss many people with TB, especially those who don’t yet feel sick. Very few studies test every patient regardless of symptoms or chest X-ray findings to see how much silent TB we’re missing,” Dr Mendelsohn said.

TB detection is not happening early enough

As part of this study, researchers from RePORT South Africa Network – a research consortium focused on infectious diseases, headed by scientists at SATVI, visited households in three South African communities and offered sputum lab tests to all adults who’ve been in contact with people with TB, even if they were asymptomatic or presented with a normal chest X-ray.

The research found that 80% of participants with TB were asymptomatic. More than half of this group of responders also presented with chest X-rays that showed no traces of active disease. Yet, they were likely spreading the disease.

To locate these patients, he said researchers recommend adopting a three-point plan:

• Take testing to the people – add household-level, community testing for contacts of TB patients and other high-risk groups, even when they feel well.

• Update screening playbooks – programmes that use symptoms and X-rays alone could build in simple microbiological tests so fewer people with TB are missed.

• Measure the real burden – national TB surveys should include universal sputum testing in contacts and other high-risk groups to avoid undercounting silent TB.

“In short, relying on symptoms or X-rays alone means many infectious people are not being found and treated early. We are not detecting TB early enough and mostly treating people with more advanced disease who self-present to the clinic. If we want to cut transmission, we need to find TB earlier by going into communities and offering tests before people recognise their symptoms,” Mendelsohn said.