The clock is ticking…..and we do not have much time in hand. Every moment is precious, so is detection of every Tuberculosis (TB) case.
The count of patients is increasing by minutes, overwhelming the world. TB is the 2nd most common cause of mortality by infectious disease, in the world. Almost 1/4th of the world is infected with TB, although not all have developed the disease, a compromised immunity can trigger the disease onset. And as a clinician I experience these alarming statistics first hand. Despite the increased efforts to identify and treat TB, almost 1 death every 20 seconds is still recorded. Half a million new multi-drug resistant TB (MDR-TB) cases are added to the count every year worldwide and this threatens to claim more lives than ever and reverse the progress made over past few decades.
The TB causing pathogen Mycobacterium tuberculosis, has evaded our attempts to overpower it by developing resistance to at-least two of the most powerful anti-TB drugs namely Rifampicin and Isoniazid which had saved millions of lives earlier. This resistance results in what is categorized as MDR-TB (multi drug resistance TB). As clinicians we try to overcome this by changing the regimen and including other drugs which may still work effectively. The MDR-TB treatment regimen is extensive (almost a 2-year course), with drugs that can have major prolonged side effects like weakened joints, skin-discolouration, hearing loss or liver damage. It takes toll on the patient causing increased morbidity and affects the quality-of-life drastically. These treatment modalities being very expensive, often cause heavy financial burden on the patient and family. Many-a-times, these exhausting regimens, might even fail to cure the patients. In some cases the patients may be resistant to second line drugs also and are classified as XDR or extensively drug-resistant TB (XDR-TB). Drug resistance complicates and prolongs the treatment. The World Health Organization (WHO), estimated approximately nearly 500,000 MDR-TB cases and approximately 50,000 cases of XDR-TB globally last year. More than 1million people die yearly due to drug-resistant TB (DR-TB) and steps have to be taken relentlessly to avoid this.
The WHO as well as Governments of all countries devise strategic plans from time to time, to come up with ways and means to reach the TB eradication goal. The TB National Strategic Plan (NSP) 2020 – 2025 in India, by the Government of India (GoI) envisaged strategies to eradicate TB by the year 2025. The National Tuberculosis Elimination Program (NTEP) applauded by WHO, has taken up the responsibility of expanding the accredited diagnostic network; however, despite the advances, only 22% of the estimated DR-TB cases received appropriate and timely anti-TB therapy, highlighting gaps in the system. Individuals suffering from MDR and XDR-TB, experience a wide variety of resistance pattern. Delay in treatment initiation, can give rise to many more cases and thus it is very crucial to start the treatment as soon as possible. Alas, in most of the cases, the treatment decisions are made in absence of detailed drug-susceptibility test (DST); increasing the resistance, manifold. DST is carried out to identify, which drugs can be used for treating that particular patient and to understand towards which drugs has the patient developed resistance. This can help the clinician to opt for other treatment regimen.
A drug-resistance pattern of the pathogen strain is encoded in its gene and the recent technological revolution of whole genome sequencing (WGS) can help fathom deep within, to identify the resistance genes. Whole genome sequencing (WGS), allows screening of the entire genome identifying the causative agent and revealing the drug resistance, in a very short period of time. This knowledge can arm the clinicians with better understanding, guiding them to start the appropriate treatment at the earliest. As a clinician, it is most important to get the accurate diagnosis as early as possible, for initiating the appropriate treatment. This can save a lot of agony and valuable time for the patient, including reducing the treatment expenses.
TB surveillance is a very important module in controlling and eliminating TB, with the surveillance data influencing the health strategies and policies and WGS can play a crucial role, facilitating a comprehensive and detailed depiction of the drug resistance. Inclusion of WGS in the private sector healthcare services along with the government controlled services, can result in speeding up the process to reach the goal of TB eradication.
Early and detailed diagnosis of TB and MDR-TB patients, along with their complete drug-resistance profile, can help initiate appropriate treatment regimen, thereby saving millions of lives worldwide.