Tuberculosis or TB remains a significant health problem in Asia and Africa causing extensive human suffering and loss of life. In recent years the causative bacteria has become resistant to available anti-TB drugs. The resistance can be of various levels, such as MDR or multi-drug resistant TB, when the most commonly used drugs rifampicin and isoniazid become ineffective. It becomes difficult to treat XDR or extensively drug resistant TB where the bacteria become resistant not only to these two drugs but also injectable and other second-line drugs.
A little over a year ago, 12 cases of XXDR or extremely drug resistant TB were discovered in Mumbai. This was followed by the discovery of 9 cases of XXDR-TB in South Africa a month ago. In XXDR-TB most of the known combinations of anti-TB drugs become ineffective and most patients have fatal outcomes.
The emergence of drug resistant forms of TB and their growing incidence is worrying and represents a public health challenge not only in India but also globally. According to the World Health Organisation’s Global TB report 2012, India, China, Russia and South Africa have almost 60% of the world’s MDR-TB burden. A similar report by them stated that in 2010, India had an estimated 63,000 notified cases of DR TB.
There are multiple causes of drug resistance TB. These include: poor management of TB treatment which includes inconsistent or partial treatment, prescription of incorrect treatment regimens or an unreliable or erratic supply of drugs. , The use of spurious serology based diagnostic tests leading to inaccurate diagnosis is also an important contributing factor.
The diagnosis and treatment of drug resistant TB is also more complicated, expensive and problematic than that of regular TB. The diagnosis of drug resistance TB can only be carried out in those laboratories which have facilities to undertake drug sensitivity testing (DST) to first-line drugs. Those patients found to have MDR-TB are then given second-line drugs.
In recent years, the government has made a conscious effort to scale up DOTS Plus services i.e. a specialized strategy that focuses on drug resistant TB and is now available across 35 States in India. Introduction of newer diagnostic tests such as Xpert MTB/RIF which can detect MDR-TB from the sample as well as resistance to rifampicin, a surrogate marker for MDR-TB, in less than two hours has become important to rapidly diagnose MDR-TB.
However, even the Xpert MTB/RIF is not free of challenges and some of these include the need for a constant supply of electricity and the high cost of the instrument and cartridges. Moreover, waste management of cartridges and its utility in extra-pulmonary and smear negative samples has been questionably low.
India is plagued by a number of complex challenges when it comes to accurately diagnosing and treating drug resistance TB. Some of these include the limited availability of diagnosis and treatment services for drug resistant TB in the public sector. In the private sector these facilities might be available but are expensive and unaffordable for most patients.
A related challenge is the rampant use of incorrect diagnostics used by the private sector that could be driving treatment failures and the emergence of drug resistant TB. India does not currently have the large scale laboratory capacity to conduct quality-assured culture and DST on the millions of patients suspected with TB. This leads to a delay in diagnosis of drug resistant TB and in turn perpetuates the cycle of TB transmission.
In order to effectively tackle drug resistant TB, there is a need to urgently engage the private sector. The National TB Programme should consider expanding beyond earlier public private engagement programmes to create new and sustainable partnerships that can help effectively monitor the activities diagnosis and treatment in the private sector. Studies have shown that community-based initiatives can help reduce defaulting and improve treatment outcomes. While some raise concerns about the private sector being profit oriented, we must engage them in a way that reinforces the need for correct diagnosis and treatment for the patient. Public awareness of initiatives such as DOTS and DOTS Plus is also important.
In 2012, a number of key decisions were taken by the government in an effort to enhance TB control. This included the banning of inaccurate serology-based tests to diagnose TB, making TB a notifiable disease i.e. mandatory reporting of TB cases to the government and the launch of a case-based, web-based recording and reporting system for TB. All the above developments, if effectively implemented will definitely help enhance the prevention and control of TB and more specifically drug resistance TB in the long run. However, we cannot be complacent, TB is an airborne disease that recognizes no boundaries. We must act now particularly to engage India’s vast private sector if we wish to control the menace of rising drug resistance.
Dr. Sarman Singh is Professor and Head, Clinical Microbiology Division, Dept of Laboratory Medicine, AIIMS, New Delhi.