World's most deadly infection is on the rise in England - and it's being spread simply by breathing

The top infectious killer, which mostly affects the lungs, is thought to be mainly spread through coughing. However, a new study suggests this is not the main route of transmission.

In fact, more than 80 percent of patients with TB do not experience a cough and it can be spread simply by breathing, scientists warn. This implies that the deadly bug is spreading unchecked through populations.

Research led by Amsterdam UMC and the Amsterdam Institute for Global Heath and Development analysed data on more than 600,000 individuals in Africa and Asia and found that 82.8 percent of those with tuberculosis had no persistent cough and 62.5 percent had no cough at all. These results are published today in The Lancet Infectious Diseases.

"Our results indicate the probable reason why, despite huge efforts to diagnose and treat the disease, the tuberculosis (TB) burden across Africa and Asia is hardly declining. We already knew that there was a giant gap between the 10.6 million who get ill with tuberculosis and the 7.5 million cases that were registered by health authorities in 2022," said Frank Cobelens, Professor of Global Health at Amsterdam UMC and Senior Fellow at the AIGHD.

"A persistent cough is often the entry point for a diagnosis, but if 80 percent 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 added.

Not our problem right? Think again. TB cases are now above pre-pandemic levels in England and cases are steadily rising.

Figures published last month by the UK Health Security Agency (UKHSA) in its TB annual report, show that tuberculosis cases in England in 2022 were stable compared to 2021.

However, additional data indicates that cases of TB in England rose by 10.7 percent in 2023 compared to 2022. The rise signals a rebound of TB cases to above pre-pandemic levels.

While cases remain relatively low in England, 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.

So far, TB has been recorded in both UK born and non-UK born populations and the largest rises in cases have been in urban centres in London, the North West and West Midlands. However, there has also been increases in the South West and North East regions where TB incidence is low.

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For the latest study, researchers analysed the results of national monitoring schemes in 12 countries, and found that alongside the lack of a cough, more than a quarter of those with TB had no symptoms at all, with both of these traits being more common in women than in men.

Furthermore, the study showed that a quarter of those without cough have high loads of bacteria in their sputum and are probably highly infectious.

"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. 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" said Professor Cobelens.

TB is a bacterial infection that most frequently affects the lungs, which is when it is infectious. Symptoms include:

• A cough that lasts more than three weeks
• High temperature
• Drenching night sweats
• Loss of appetite
• Weight loss

It can be treated with a prolonged course of antibiotics but can be serious, particularly if not treated.