If you think that tuberculosis (TB) is a disease of the past, you are right and also very wrong.
On March 24 every year, World Tuberculosis Day is commemorated around the globe. You may be wondering why we still need a global event to draw attention to a disease that most newborns around the world are vaccinated against. Like many others, you may think that we must be close to eliminating TB, since we have been able to cure it with cheap and easily available drugs for 60 years.
Unfortunately, we are not even close to elimination. In fact, TB now kills more people than any other infectious disease. By the time you have finished reading this article, approximately 15 people will have died from TB and another 90 will have been newly infected. To put it in perspective, dengue - an infectious disease that Singaporeans hear about often - is responsible for 22,000 deaths around the world every year. At 1.5 million, TB kills more than 70 times as many people.
TB is able to keep spreading in this way because the vaccine (called BCG) provides some protection to immunised children but unfortunately not to adults, and there is no easily available diagnostic tool to find cases before the infection spreads.
It so happens that Singapore is located in the heart of the TB epidemic, being close to Cambodia, Myanmar, Indonesia, China and India - countries which are known to have the highest number of TB cases in the world. There are as many TB patients in South-east Asia as people living in Singapore! At 5.4 million, this region houses more people with diagnosed and undiagnosed TB than any other region in the world, including Africa. TB therefore poses a risk and an opportunity for Singapore.
While the burden of TB has been decreasing slowly in many countries, the number of patients with drug-resistant forms of TB has been increasing steadily. A frightening scenario will be one where multidrug-resistant TB is the new norm.
Luckily, 90 per cent of patients, including the vast majority of the 1,500 Singapore residents who develop TB every year, are cured. However, treatment lasts at least six months, and a specific combination of drugs needs to be taken daily to successfully defeat the persistent bacteria. In countries struggling to control TB (including those that surround Singapore), many TB patients are not treated properly. They are often unable to take their treatment daily or stop before the full treatment course is completed. Others access poor quality medications or are prescribed inadequate doses of the required drugs.
In these situations, the TB bacteria are exposed to the required drugs, but not enough to kill them all. This allows a more deadly drug-resistant form of bacteria to be generated, which can spread to other patients and across countries. And because TB patients are treated with several drugs at the same time, the bacteria adapt to be untreatable by multiple drugs. To put it simply, by not treating TB properly, we have created a monster known as multidrug- resistant TB.
Multidrug-resistant TB has been referred to, frighteningly, as "airborne cancer" since it is very hard to treat and medications can have devastating side effects, including hearing loss. The cost of treating such a patient is also at least 50-fold higher than that needed to treat a TB patient who does not have a drug-resistant infection. Unless we take drastic steps, it is estimated that multidrug-resistant TB will cause 75 million deaths globally and cost a staggering $23 trillion over the next 35 years.
Since multidrug-resistant TB is so much harder and more expensive to treat, prevention is the best approach. The key to prevention is making sure that TB patients receive complete treatment with correct medications so they are cured. To do this, we need better drugs that can cure patients in less than six months and stronger health systems which support patients in completing treatment.
While the threat from TB is real and of concern, three features give Singapore the opportunity to be a global leader in the fight against this disease.
First, the breadth of Singapore's growing research infrastructure and human resources - stretching from genomics and drug discovery to implementation science - allows a full package of "bench to bedside" work to be conducted. Drawing upon these strengths would give Singapore an edge in developing new strategies and technologies that many other regional countries cannot. SPRINT TB, which stands for Singapore Programme of Research Investigating New Approaches to Treatment of Tuberculosis, exemplifies such an approach. It brings together four streams of research from discovery of new drug targets in the bacteria to drug development, trials of new drugs in patients and finally, strategies to ensure drugs reach populations in need.
Second, being surrounded by low-income, high TB burden countries puts Singapore in a prime position for regional engagement on research and capacity building, which can turn the tide on TB control. A crucial step towards this has already been taken: This year, the National University of Singapore initiated its first overseas TB research programme in Cambodia. The programme is led by its Saw Swee Hock School of Public Health and aims to inform the Cambodian National TB Programme on the best strategies to reduce TB over the next 15 years.
Finally, Singapore has an opportunity to impact funding for TB research and development (R&D) at a global level. Worldwide investments in TB research are incredibly low. A recent report by the Treatment Action Group, which tracks global investments in TB R&D, revealed an annual shortfall of $1.8 billion in funding needs. This means that even a relatively small investment can put an organisation or country among the top TB funders. Indeed, this was true for Singapore, which appeared in the Treatment Action Group report for the first time last year, emerging globally as the country that invested the most in TB research (as a percentage of its GDP). This demonstrates the potential for Singapore to be a leader in conducting and also funding essential TB research, if the commitment is sustained.
By 2035, the global goal endorsed by the World Health Organisation is to reduce the number of new TB cases by 90 per cent and end the worldwide TB epidemic. This is an ambitious target that looks impossible to achieve in the current scenario. While the burden of TB has been decreasing slowly in many countries, the number of patients with drug-resistant forms of TB has been increasing steadily. A frightening scenario will be one where multidrug-resistant TB is the new norm. Now is the time for the global community to step up efforts in TB surveillance and control.
TB continues to evolve; it crosses political, economic and geographical boundaries. Our approach to TB control must do the same.
• The writer is an assistant professor at the Saw Swee Hock School of Public Health, National University of Singapore and lecturer in global health and development at the London School of Hygiene and Tropical Medicine.