Nearly two decades ago, the World Health Organisation (WHO) declared tuberculosis (TB) a global health emergency but even today it remains a major public health challenge worldwide with India accounting for one-fifth of the global TB cases and approximately 1,000 TB deaths per day. The direct and
indirect costs of TB in the country approximately amount to $23.7 billion annually. All this makes one wonder whether we have responded well to combat this dreadful disease.
The answer lies in understanding the landscape of scientific, policy and attitudinal changes that have taken place, particularly in recent times. With a ban on serological tests for TB in India last year, policy-makers demonstrated their understanding that an accurate diagnostic test for TB is sorely needed. Serology-based TB tests have been widely used by the private sector in India which sees around half of all TB patients, despite the knowledge that these tests were misleading and placed patients’ lives at risk.
Making TB a notifiable disease was a milestone that reflected the government’s and policy-makers’ resolve to understand and tackle the problem. The government also set an ambitious goal of providing universal access to quality diagnosis and treatment by further strengthening the already highly successful Revised National Tuberculosis Control Programme (RNTCP). However, undiagnosed and poorly managed TB patients remain major issues to deal with.
The most commonly used method to diagnose TB — sputum smear microscopy — detects only half of TB cases. The ‘gold standard’ test for TB, the culture test, requires up to two weeks and a skilled workforce for effective TB diagnosis.
Several new rapid molecular tests endorsed by the WHO, such as the Xpert MTB/RIF, are available or are being developed for faster and more accurate TB diagnosis. The Xpert MTB/RIF can reduce diagnosis time from two weeks to two hours and can detect TB in patients with resistance to at least one of the first line drugs, rifampicin. The test is relatively easy to perform, requiring little training and has a high sensitivity in smear-negative pulmonary TB. These innovations have become especially relevant to India, which also has a growing burden of drug-resistant TB. However, the test is yet to be fully assessed for its suitability in Indian conditions, including extreme heat, humidity and access to the hard-to-reach populations in rural areas. Further, an uninterrupted power supply is a pre-requisite for its appropriate usage. The introduction of an accurate and quick test like the Xpert MTB/RIF is vital, but it is also important to create a system for its sustainability. Although the government has launched the diagnostic across 18 urban settings in India, its cost may remain a challenge and may prohibit its access to the vulnerable populations. Though lower prices are being negotiated for the public sector in India, costs of the equipment and disposable cartridges for the test remain unaffordable to the 50% of patients who access the private sector.
Now that the scientific rationale for quick and accurate diagnosis is firmly established, it’s time we develop solutions more suitable to the needs of the country. In fact, it should be possible to go beyond and think of ways of developing diagnostics for multidrug-resistant TB and extensively drug-resistant TB, and development of novel platforms like breath bio-markers. An ideal solution will be a handheld device which can operate without the need for continued electrical supply. We have the knowledge and the expertise and with the continuous support and involvement of all the stakeholders we can reach the goal of providing universal access to treatment and care for all TB patients by 2015.
VS Chauhan is director, International Centre for Genetic Engineering and Biotechnology, New Delhi.
The views expressed by the author are personal.