IJE Advance Access originally published online on April 11, 2007
International Journal of Epidemiology 2007 36(2):394-395; doi:10.1093/ije/dym023
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Commentary: Back to basics—good news from a birthplace of DOTS
Senior Technical Advisor, Care and Treatment, Program Services, Office of the United States Global AIDS Coordinator, 2100 Pennsylvania Avenue NW, Washington DC, USA.
E-mail: granichrm{at}state.gov
Accepted 30 January 2007
Although India's tuberculosis (TB) control program has much to be pleased with, working on TB in India and elsewhere can be a daunting endeavour. The list of seemingly insurmountable global challenges is off-putting, to say the least: 8.9 million new TB cases each year; 1.7 million TB deaths annually, despite the existence of an effective cure; a devastating HIV/AIDS pandemic; archaic diagnostic technology often dating back to the early 1900s; pitiable investments in public health infrastructure; and now—the latest grim news regarding extensively drug resistant (XDR) TB, make for very heavy sledding.1–4
XDR-TB is particularly alarming in the context of the HIV/AIDS pandemic. Early reports suggest a TB mortality rate of nearly 100% among people living with HIV/AIDS.2,4 To make matters worse, while the emergence of XDR-TB was by no means unexpected, its intractability is exacerbated by a global response which is crippled by chronic lack of investment in public health, and specifically in TB control programs.
In the face of these prevailing challenges, it is good news indeed to read the paper by Subramani et al.5 which appears in this issue. The active community surveillance of different TB control measures in Tamil Nadu, India, which is unique in its longitudinal scope, provides important insights into the value of the WHO-recommended DOTS strategy. Although there is a large and growing body of evidence that supports the DOTS strategy,6,7 the authors’ extensive community surveys over a 31-year period convincingly document the impact of a well-implemented DOTS program on TB prevalence in the community.
This study, which benefited from a long-term public health investment in the understanding of the epidemiology of TB and the effects of TB control measures, has found that implementing a DOTS program accelerated the decline of prevalence in culture-positive TB, by nearly 6 times the pre-DOTS implementation rate. In fact, the 2.5 years of DOTS implementation in this small community accounted for one quarter of the decline in culture-prevalence TB over the entire 33-year period. Another key implication of these findings is the inference that in the presence of a well-functioning TB control program, monitoring case notifications can provide a reasonable approximation of TB epidemiology in the community.
For anyone with experience in implementing a well-functioning DOTS program in settings with a low prevalence of HIV/AIDS and drug resistance, these findings—while they are perhaps more dramatic than one might have expected—make sense. What does not make sense is that it has taken so many governments, communities, non-governmental organizations, donors, academics, patients and activists so long to recognize the importance of the DOTS management system—and to demand that it be implemented in every community affected by TB.
There are a number of important issues that should be considered when interpreting these study findings. The first is the significant public health investment and value of the study area. Although it was necessary to make some assumptions regarding the socioeconomic situation of the community over time, the implementation of the TB control program, and the long-term sustainability of the accelerated downward trend under DOTS, the study site has yielded valuable insights. Foresight, as well as a considerable, sustained investment, laid the foundation for this and future studies of TB control interventions. The study team and researchers deserve mention: their expertise in conducting meticulous, large-scale community surveys is rare, and this, in combination with a long-term approach, maximized the study teams’ potential. Public health authorities and donors would do well to consider lessons learned from this study regarding how to make the most with scarce research dollars when evaluating key public health interventions such as DOTS.
Another key consideration is the significant, positive impact of the rifampin-based DOTS regimen in a study area with low levels of rifampin resistance. India, one of the birthplaces of DOTS, has made remarkable recent progress in controlling TB.6 Rifampin resistance was reportedly low in the study area, but since India has 
1.8 million new TB cases each year, even low proportions of multi-drug resistance (range 0.5–3.0%, reported from population-based studies) are a cause for serious concern.4,6 India's national TB program has extensive case notification, case holding and prevalence of infection data and this study should prompt a thorough analysis of case detection trends, including consideration of relevant co-factors (e.g. drug resistance, HIV prevalence, duration and starting date of DOTS program). The findings also provide a fresh example of the global urgency of protecting rifampin and preventing the widespread development of drug-resistant TB. In light of the few promising drugs in the pipeline, the estimated annual global total of 424,000 new cases of multi-drug resistant TB, the incomplete and weak implementation of DOTS in many countries and the spectre of XDR-TB (particularly in settings of high HIV prevalence), our window to control TB in many communities may be closing.4
The low prevalence of HIV within the study community begs the question of the impact of DOTS in higher HIV prevalence areas in India and elsewhere. While DOTS implementation was clearly effective in this low HIV-prevalence south India study setting, to my knowledge there are no similar longitudinal studies in areas with higher HIV prevalence. In populations with higher HIV prevalence, TB control requires interventions that target both TB and HIV/AIDS.8 HIV/AIDS interventions (e.g. HIV prevention programs, antiretroviral therapy) indirectly target tuberculosis by reducing the number of people who have HIV/AIDS and preventing or delaying the development and transmission of TB.8–10 To improve the performance and impact of TB control programs, the World Health Organization has launched the revised ‘Stop TB’ Strategy. The new strategy includes intensified TB case-finding, treatment of latent TB infection with isoniazid, prevention of HIV infection, cotrimoxazole preventive therapy and antiretroviral therapy.10 Although elements of the new strategy are based on solid research, implementation will prove to be challenging and will require far better collaboration between HIV/AIDS and TB programs than currently exists in most settings. For the sake of millions of people, technical experts and health authorities in India and elsewhere should urgently ‘re-imagineer’ TB and HIV/AIDS programs, to improve access to life-saving services and reduce the incidence and prevalence of TB and HIV/AIDS in communities that have been affected by both diseases.
With these considerations in mind, this study confirms what we know from historical studies and surveillance reports of TB case notification data: that a strong TB control program based on the DOTS management system can have a significant impact upon TB in the community. It is an important study and provides a strong foundation for the next generation of inquiries into the impact of the newly revised Stop TB strategy.
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The views of the author do not represent the viewpoint of the Office of the Global AIDS Coordinator.
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1 Reid A, Scano F, Getahun H, et al. Towards universal access to HIV prevention, treatment, care, and support: the role of tuberculosis/HIV collaboration. Lancet Infect Dis (2006) 6:483–95.[CrossRef][Web of Science][Medline]
2 Notice to Readers: revised definition of extensively drug-resistant tuberculosis. MMWR (2006) 55:1176.
3 Gandhi NR, Moll A, Pawinski R, et al. High prevalence and mortality from extensively drug-resistant (XDR) tuberculosis in TB/HIV coinfected patients in rural South Africa. XVI International AIDS Conference, 2006: Toronto, Canada.
4 Aziz MA, Wright A, Lazlo A, De Muynck A, et al. Epidemiology of antituberculosis drug resistance (the Global Project on Anti-tuberculosis Drug Resistance Surveillance): an updated analysis. Lancet (2006) 368:2142–54. WHO/International Union Against Tuberculosis And Lung Disease Global Project on Anti-tuberculosis Drug Resistance Surveillance.[CrossRef][Web of Science][Medline]
5 Subramani R, Santha T, Frieden TR, et al. Active community surveillance of the impact of different tuberculosis control measures, Tiruvallur, South India, 1968–2001. Int J Epidemiol (2007) 36:387–93.
6 accessed 1/25/07. www.tbcindia.org.
7 China Tuberculosis Control Collaboration. The effect of tuberculosis control in China. Lancet (2004) 364:417–22.[CrossRef][Web of Science][Medline]
8 Williams B, Maher D. Tuberculosis fuelled by HIV: putting out the flames. Am J Respir Crit Care Med (2007) 175:6–8.
9 World Health Organization. Strategic framework to decrease the burden of TB/HIV. In: No. WHO/CDS/TB/2002.296 (2002) Geneva. Anonymous.
10 http://www.who.int/tb/features_archive/stop_tb_strategy/en/index.html.
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