Epidemiology

According to the World Health Organization (WHO), one third of the 6.8 billion people are latently infected with the TB bacteria. It is estimated that about 10% of these people, i.e., 227 million people will develop the active TB disease in their lifetime. If these patients are not treated, the WHO estimates that they would infect 10-15 other people until their death, which illustrates the enormous risk of infection of this disease.

A clear downward trend in the mortality rate (see “C Mortality” in the graph below) and the prevalence rate (“B Prevalence”) can be observed throughout the years. However, when assessing the trends of these rates, the steadily increasing population must also be considered, so that the absolute values do not show any significant changes. Furthermore, it appears the rate of new cases (“A Incidence”), despite the growing population has not changed significantly, which is an additional indication for the need of TB prevention efforts.

Source: Lönnroth K, Castro KG, et al. Tuberculosis control and elimination 2010–50: cure, care, and social development. The Lancet. 2010 May 17. DOI:10.1016/S0140-6736(10)60483-7.

In 2010, there were 8.8 million new cases including 1.1 million HIV patients suffering from tuberculosis. This corresponds to a global incidence rate of 128 cases per 100,000 population. The number of patients who were infected with a resistant form of TB, was estimated to be 650,000 in 2010. In Western Europe, the incidence rate was 17 cases per 100,000 population, and the number of new cases in Germany in 2010 was only 4330. Such low statistics naturally only represent one side of the scale and the majority of the remaining case load is placed on 22 high-burden countries (HBC) that suffer 80% of new cases worldwide. These countries are led by India and China, followed by other emerging and developing countries.

In spite of the 8.8 million new cases, only 5.7 million people were officially enrolled as TB patients in WHO-approved government treatment. That means 3.1 million people probably received TB care that was not in accordance to WHO standards or sanctioned by the public health system, if it were ever treated at all. Among patients with drug-resistant forms of TB an even larger gap existed between new cases and patients enrolled. In 2010, it is estimated that only 16% of drug-resistant TB patients received appropriate treatment.

The global number of deaths fell in 2010 by 1.7 million to 1.4 million people, including 350,000 HIV victims. While this is an encouraging trend, it still corresponds to a death rate of 3.800 people per day! 95% of these deaths were in developing countries.

In 2009, 9.7 million children became orphans due to tuberculosis-related deaths in their family. The disease is also one of the three leading causes of death for women between 15 and 44.

In 2010, $510 million US Dollars were missing from the global budget for tuberculosis control. It is expected that this number has grown to almost a billion U.S. dollars in 2012.

 

Below is a brief comparison between the three major infectious diseases to place the global TB burden into context:

The number of new cases is still higher than the number of patients treated, which means that the disease continues to spread. And the number of resistant infections grows daily without being treated appropriately. The gap between funding needs and available resources becomes increasingly larger. We intend to combat these trends with our work.

In the next section we discuss the problems and barriers related to the tuberculosis care and control and focus particularly on the reasons for why a disease is still a real threat today despite the discovery of appropriate medicines more than 50 years ago.

>> Barriers