Tuberculosis (TB) is a major global health problem. It causes ill-health among millions of people each year and ranks alongside the human immunodeficiency virus (HIV) as a leading cause of death worldwide. According to the WHO Global TB Report 2015, there were an estimated 9.6 million new TB cases—5.4 million among men, 3.2 million among women and 1.0 million among children in 2014. There were also 1.5 million TB deaths (1.1 million among HIV-negative people and 0.4 million among HIV-positive people), of which approximately 890 000 were men, 480 000 were women and 140 000 were children. The number of TB deaths is unacceptably high. But timely diagnosis and correct treatment can easily cure TB.
The burden of TB can be measured in terms of incidence, which is defined as the number of new and relapse cases arising in a given time period, usually one year. Prevalence of the disease is defined as the number of cases of TB at a given point in time; while mortality is defined as the number of deaths caused by TB in a given time period, usually one year.
Notifications of TB cases provide a good proxy indication of TB incidence in countries that have both high-performance surveillance systems (for example, there is little under-reporting of diagnosed cases) and where the quality of and access to health care means that some cases may not be diagnosed. In several countries where these criteria are not yet met, better estimates of TB incidence can be obtained from an inventory study which is a survey to quantify the level of under reporting of detected TB cases. If certain conditions are met, capture-recapture methods can also be used to estimate TB incidence.
The Millennium Development Goals (MDG) target to halt and reverse TB incidence has been achieved on a worldwide basis, in each of the six WHO regions and in 16 of the 22 high-burden countries that collectively account for 80 per cent of TB cases. Globally, TB incidence has fallen by an average of 1.5 per cent per year since 2000 and is now 18 per cent lower than 2000 levels. The incidence rates of Bangladesh, China, India and Pakistan are given in Figure 1.
In countries with a relatively high burden of TB, the prevalence of bacteriologically-confirmed pulmonary TB can be directly measured in nationwide population-based surveys using sample sizes of around 50,000 people. Survey results can be used to produce a national estimate of TB prevalence that includes all forms of the disease.
There were an estimated 13 million prevalent cases (range, 11 million–14 million) of TB in 2014. By 2015-end, it is estimated that the prevalence rate will have fallen 42 per cent globally since 1990, missing the target of 50 per cent reduction. However, two regions met the target before 2015 (the Region of the Americas and the Western Pacific Region); while the South-East Asian Region reached the target (according to the best estimate) in 2015. TB prevalence is falling in all the other three regions. Among the 22 high burden countries (HBC), nine are assessed to have achieved a 50 per cent reduction target, as compared to 1990 levels (Fig. 2). TB prevalence rates of Bangladesh, China, India and Pakistan are given in Figure 2.
TB mortality among HIV-negative people can be directly measured using data from national vital registration (VR) systems, provided that these systems have high coverage and causes of death are accurately coded according to the latest revision of the international classification of diseases (ICD-10). For the vital registration data of sufficient coverage and quality the WHO Global TB Report 2015, used 127 countries’ survey data including India. The combined total of 129 countries accounted for 43 per cent of the estimated number of TB deaths globally in 2014.
Globally, the mortality rate (excluding deaths among HIV positive people) fell 47 per cent between 1990 and 2015, narrowly missing the target of a 50 per cent reduction. However, two WHO regions met the target about ten years in advance of the deadline (the Region of the Americas and the Western Pacific Region), and the Eastern Mediterranean and South-East Asia Regions reached the target (according to the best estimate) by 2015. The mortality rates of Bangladesh, China, India and Pakistan are given in Figure 3.
Tuberculosis cases in India
As per WHO Report, the estimated incidence of TB in India has declined progressively from 216 per lakh population per year in 1990 to 167 per lakh population per year in 2014. The estimated prevalence of TB has declined from 465 per lakh population per year in 1990 to 195 per lakh population per year in 2014. India achieved the MDG for TB to halt and start reversing the incidence to half the prevalence and mortality rates by 2015 as compared to the 1990 baseline. The estimated mortality due to TB has declined from 38 per lakh population per year in 1990 to 17 per lakh population per year in 2014. The decline in incidence, prevalence and mortality is estimated on an all India basis and includes the north-eastern states and Himachal Pradesh.
There has been an overall decline in the mortality, prevalence and incidence rate in India from 1990 to 2014. The Global Tuberculosis Report 2015 shows the detail estimates of TB burden of India in 2014 (Fig. 4). The Report also reveals the percentage of TB cases with multidrug-resistant TB (MDR-TB) in the same year. Out of the total TB cases 15 per cent have shown to relapse. And another 2.2 per cent new cases were registered according to the survey in 2014.
The government has taken the following measures under the Revised National Tuberculosis Control Programme (RNTCP) which is supported under the National Health Mission (NHM):
- More than 13000 designated microscopy centres have been established for quality diagnosis of TB.
- Treatment for drug sensitive TB is provided through a network of more than 400,000 directly observed treatment (DOT) centres, where a dedicated box containing a complete course of treatment is available for each patient.
- Most government hospitals, community health centres (CHCs), primary health centres (PHCs), sub centres function as DOT centres. Additionally, NGOs, private practitioners (PPs) community volunteers, anganwadi workers, women self-help groups also function as DOT providers/DOT centres.
- The programmatic management for drug resistant TB (PMDT) services is provided in all 36 states/union territories of India.
- Diagnosis of drug-resistant TB is undertaken through quality assured drug susceptibility testing at 64 culture and drug susceptibility testing (C-DST) laboratories.
- Cartridge based nucleic acid amplification (CBNAAT) test machines have been installed at 121 sites for early detection of rifampicin resistance among TB cases, including 30 machines at anti retroviral therapy (ART) centres for detection of TB in people living with HIV AIDS.
- Diagnosis and treatment (including drugs) is provided free of cost under RNTCP.
- TB has been made a notifiable disease. This mandates all healthcare providers to notify every TB case diagnosed or treated by them to local authorities. A total of 184,802 cases were notified from the private sector in 2015.
- RNTCP in collaboration with National Informatics Centre (NIC) has developed and implemented a web enabled and case based application named ‘Nikshay’ to improve TB surveillance, treatment and monitoring of TB cases.
- A“Call to Action for TB- Free India” campaign was initiated in 2015 to galvanise all stakeholders to commit themselves towards a TB- Free India.
Despite the worldwide decline in TB cases, detection and treatment gaps need to be addressed, funding gaps closed and new tools developed to bring an end to TB.