During the period 1995-2008, 36 million people were cured from tuberculosis (TB) and up to 6 million lives were saved compared to the performance of TB control programs at the start of the DOTS era in 1995.
However, with 1.8 million estimated deaths every year, TB still takes a huge toll, especially for the world’s poorest people.
It is a leading cause of death in people in the most economically productive age-groups. There were around 11 million active cases of TB in 2008, with 95% of cases in low- and middle-income countries.
In the first paper in The Lancet series on Tuberculosis, Dr Mario Raviglione and Dr Knut Lönnroth, Stop TB Department, WHO, Geneva, Switzerland, and colleagues look at the global burden of TB and what needs to be done to eliminate it by 2050.
Most cases cured by available drugs
Available drugs can cure most cases of TB, and such intervention is highly cost-effective, leading to economic gains up to 10 times what is spent on treatment. Rapid expansion of the standardised approach to TB diagnosis and treatment that is recommended by WHO (the Stop TB strategy) has allowed more than 36 million people to be cured between 1995 and 2008, averting up to six million deaths.
TB/HIV collaboration has improved recently, but further rapid improvements are needed. Quality controlled management of multidrug-resistant (MDR) TB is improving, albeit very slowly.
Part of Millennium Development Goal 6 to halt and begin to reverse TB incidence by 2015 is estimated to have been reached in 2004 globally. Global incidence was estimated at 139 cases per 100,000 population in 2008, down from 143 in the apparent peak year of 2004. However, the decline is less than 1% per year.
With present efforts, the targets to halve prevalence and death rates by 2015, compared with 1990 rates, will probably be met in most regions, but might not be met worldwide. The long-term elimination target, to reduce incidence to less than one case per million by 2050, will not be reached with existing technologies and approaches.
Global detection improved
22 countries contain 80% of the world’s cases of TB, including Brazil, China, Russia, India, Burma, South Africa and Zimbabwe.
Encouragingly, all these 22 countries are implementing standardised diagnosis, treatment and management of TB i.e. the DOTS component of the Stop TB Strategy.
The global case detection rate improved six-fold between 1995 and 2008, but is still at 61%—thus 39% of active TB cases remain undetected every year by national TB programs.
To speed up the decline in TB burden, case detection rates need to be improved substantially, and cases must be identified much earlier. Synergy with additional interventions (for other diseases) should be explored, including interventions to prevent TB.
HIV and TB co-infection is a major problem, especially in Africa. But of around 1.4 million people estimated to be co-infected, only 357,000 (less than 25%) were identified in 2008.
Intensified case detection approaches are needed, linked to general health-system strengthening, ensuring universal access to high-quality early diagnosis, treatment, and care for all forms of this disease, including people infected with HIV and those affected by multidrug-resistant TB.
Screening at high-risk areas, cost effective
The authors say that a rapid and simple point-of-care test would improve early case detection substantially.
While whole-population screening might not be cost effective, it might be in high-risk subpopulations such as health-care workers,prisoners,drug addicts,homeless people, slum dwellers, refugees, migrants, displaced populations, people affected by mental illness or other high-risk groups.
Preventive therapy with the isoniazid should be scaled up. Additional prevention efforts include development of more effective vaccines, or reducing risk factors for TB, as well as their underlying social determinants.
HIV increases the risk of TB by more than 20 times. Under nutrition, smoking, diabetes and alcohol misuse can all increase this risk by 2-3 times. The paper estimates the relative threat of each of these risk factors (population-attributable fractions). For instance, in Russia, where alcohol abuse is rife, up to a third of active TB cases could be due to alcoholism.
But in South Africa and Zimbabwe, up to two thirds of TB cases are thought to be caused by HIV co-infection. Around a further third of Russian TB cases are linked to smoking, while in China and India, up to 20% of cases are linked to smoking.
Massive funding gaps
Funding for TB control in high-burden countries more than doubled between 2002 and 2009.
Nevertheless, large funding gaps remain. The funding shortfall expected in these countries in 2010 is US$0.5 billion (about R36.5 billion), and in all countries the deficit in 2010 compared with the Global Plan to Stop TB is $2.1 billion (about R153.3 billion). Many countries are struggling to sustain basic diagnostic and treatment services.
The authors conclude: “Acceleration of the present decline towards TB elimination will need invigorated actions in four broad areas: continued scale-up of early diagnosis and proper treatment in line with the Stop TB Strategy; development and enforcement of bold health-system policies; establishment of links with the broader development agenda; and promotion and intensification of research.” (Lancet, September 2010)
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Dr Mario Raviglione, Stop TB Department, WHO, Geneva, Switzerland. T) +41 22 791 2663 E) email@example.com
Dr Knut Lönnroth, Stop TB Department, WHO, Geneva, Switzerland. T) +41 22 791 1628 E) firstname.lastname@example.org
Glenn Thomas, Senior Communications Adviser, WHO Stop TB Department. T) +41 79 509 0677 E) email@example.com
For full Series paper 1, see: http://press.thelancet.com/tbsp1.pdf