Silent killer: Quarter of people with TB show no symptoms, study says

Health bodies need to rethink the way they diagnose pulmonary tuberculosis (TB), researchers have warned, after a study found more than a quarter of people living with the disease do not report any symptoms at all.

Researchers, led by the Amsterdam University Medical Center (UMC), also found that 80 per cent of patients with TB do not have a persistent cough - despite this being one of the key symptoms used by doctors to identify the condition.

TB is an infection that usually affects the lungs and symptoms can include a cough that lasts for more than three weeks, feelings of tiredness or exhaustion, high temperature or night sweats, loss of appetite, weight loss and feeling generally unwell.

It is spread when infectious people cough, sneeze or spit.

Frank Cobelens, professor of Global Health at Amsterdam UMC and senior fellow at the Amsterdam Institute for Global Heath and Development (AIGHD), said the results of the study suggest why, despite huge efforts to diagnose and treat TB across Africa and Asia, the burden is “hardly declining”.

“A persistent cough is often the entry point for a diagnosis, but if 80 per cent of those with TB don’t have one, then it means that a diagnosis will happen later, possibly after the infection has already been transmitted to many others, or not at all,” he said.

TB can be treated with antibiotics but can be serious - or even fatal - if it goes untreated.  It is estimated that each year about 10.6 million people across the world contract TB but only around 7.5mn of those cases are registered with doctors.

For their study, researchers analysed data from countries in Africa and Asia with high rates of TB between 2007 and 2020. Data on 602,863 participants were analysed, of whom 1,944 had tuberculosis.

The study found that 82.8 per cent had no persistent cough and 68.7 per cent had no cough at all while  27.7 per cent displayed no symptoms at all.  TB without cough, irrespective of its duration, was also more frequent among women.

“When we take all of these factors into account, it becomes clear that we need to really rethink large aspects of how we identify people with TB,” professor Cobelens added.

“It’s clear that current practice, especially in the most resource-poor settings will miss large numbers of patients with TB. We should instead focus on X-ray screening and the development of new inexpensive and easy-to-use tests”.

In September last year health chiefs in the UK issued a warning following a rise in cases of TB as progress on battling the disease stalled.

Cases of TB increased by seven per cent in the first half of 2023, with 2,408 alerts recorded compared to 2,251 during the same period in 2022, according to the UK Health Security Agency (UKHSA).

The cases were most prevalent in people living in large cities in England and poorer areas, the agency said.

Provisional data published in February this year indicate that cases of TB in England rose by 10.7 per cent in 2023 compared to 2022 (4,850 compared to 4,380). The rise signals a rebound of TB cases to above pre-Covid pandemic numbers, the UKHSA said.

While England remains a low incidence country for TB, the current trajectory takes the UK further from the pathway to meet World Health Organization (WHO) 2035 elimination targets. UKHSA is working with partners to investigate the reasons behind the increase in TB.

A total of 1.3mn people died from TB in 2022, according to the World Health Organisation.  TB is the second leading infectious killer after COVID-19 and kills more people than HIV and AIDS.