Research published today (24 March 2014) provides critical new insight on the harmful links between smoking tobacco and developing tuberculosis (TB). Regular tobacco smoking doubles the risk that people who have been successfully treated for TB will develop TB again - a condition known as "recurrent" TB. The study is the most robust ever conducted into how smoking tobacco increases the risk of recurrent TB. It appears in the April issue of the International Journal of Tuberculosis and Lung Disease.

"More than ever before, we understand how tobacco harms people who have already been successfully treated for TB," said Dr Chung-Yeh Deng of National Yang-Ming University in Taipei , an author of the study. "No one should undergo the long, complex treatment for TB only to unknowingly place themselves at heightened risk of getting the disease again. With this research we can inform national tobacco control policies and educate patients about the risks that smoking tobacco poses.

" The researchers followed a large sample of 5,567 TB patients in Taiwan, each of whom had TB confirmed through bacteriologic testing and went on to successfully complete TB treatment. Of those patients, 1.5 percent developed a recurrent case of TB, with regular tobacco smokers twice as likely to develop recurrent TB compared with former smokers and with individuals who had never smoked tobacco. Regular tobacco smokers were defined as individuals who smoked 10 or more cigarettes - equivalent to half a pack - per day.

"Until this study was published, we didn't have a clear sense of how smoking tobacco posed risks to TB patients who have put in the hard work of completing their treatment. This is a robust study with important implications for patients, public health programmes and policy-makers alike," said Dr Paula Fujiwara, Scientific Director of the International Union Against Tuberculosis and Lung Disease (The Union), which publishes the journal.

The research was announced on 24 March to coincide with World TB Day, which marks the anniversary of Prof Robert Koch's discovery of the bacteria that cause tuberculosis in Berlin. More than a century later, Koch's discovery is still considered among the most revolutionary in the history of medicine, since it paved the way to finding a cure for the disease known in the 19th century as "The White Plague".

"You often see tuberculosis still referred to as an 'ancient' disease, but this study is further evidence that TB is a fully modern illness that is impacting people in new ways," said José Luis Castro, Interim Executive Director of The Union. "Unless we adapt our TB control strategies to respond to newly ascertained risks, such as smoking tobacco, the global rise in diabetes, and the overcrowding we see in cities as the world urbanises, we will always remain two steps behind the bacteria that cause this disease."