A study co-authored by the University of Birmingham has identified the most effective way to test people with latent tuberculosis (TB), a potentially fatal infection that has increased in the UK in recent years.

The results of a research partnership between the University, the Royal Centre for Defence Medicine, based at the Queen Elizabeth Hospital in Birmingham, and the Liverpool School of Tropical Medicine will help to improve the UK’s ability to identify people entering the country who have been infected with the bacterium that causes TB.

Diagnosing latent TB is important because the bacterium can persist in the body like a “Trojan Horse”, only to emerge and reactivate months or even years later. Treating individuals with latent TB can prevent disease developing and so prevent them infecting others.

The research study centred on Nepalese soldiers recruited to the Brigade of Gurkhas of the British Army, who were tested for latent TB using all the tests currently available. One of these, called T-Spot, was found to be better than others at detecting latent TB when used on its own.

As a result, this test has been adopted by the Ministry of Defence (MoD) as a more efficient way to identify latent TB infections. The study’s authors say it offers a strategy for diagnosing this “silent infection”, which is notoriously difficult to detect, and could be used in civilian populations.

TB is caused by the bacterium Mycobacterium tuberculosis, and is spread through the inhalation of tiny droplets from coughs or sneezes of an infected person.
Most people acquire infections abroad and will not develop disease. However, about two billion people around the world carry the bacteria in their body and five to ten per cent go on to develop active TB.

While treatment can be effective, it lasts for six months and failure to complete it can result in resistance to drugs and the reactivation of infection, making cure more difficult. This makes diagnosis of latent infections a key strategy to control disease in countries like the UK.