Amid reports of outbreaks in Paris and high schools across the United States, the World Health Organization recently announced that the number of new cases of tuberculosis went down globally for the first time. While this news reflects great progress in the fight against tuberculosis, advocates caution against complacency and remind us of the formidable work still to be done, including the rising threat of drug resistance.
When the WHO talks about this decline in tuberculosis cases, it looks at the global incidence of tuberculosis. Incidence is a measure of disease frequency that refers to the occurrence of new cases of a given disease in a candidate population over a specified time period. In this instance, we are talking about new cases of tuberculosis in the global population over one year; in 2010, this number was estimated at 8.8 million.
Another important measure of disease is mortality, or the number of deaths caused by a specific disease in a given time period. In 2010, the WHO estimated 1.4 million deaths due to tuberculosis in the world, the lowest level in a decade.
The news was met with such excitement in part because of its implications for the Millennium Development Goals and the Stop TB Targets. The Millennium Development Goals were created by the United Nations in 2000 as a plan to reduce extreme poverty and disease while advancing global development by 2015. MDG #6 aims to combat infectious disease including HIV/AIDS, malaria and tuberculosis. Specifically, by 2015 the world will halt and begin to reverse the incidence of tuberculosis.
Meanwhile, the Stop TB Partnership has set as a goal to reduce prevalence (a measure of existing cases of disease) and death rates by 50 percent by 2015 in comparison with 1990 levels. With the recent news, the world is on track to achieve the MDG target of falling incidence, and five out of six regions (the exception being Africa) can achieve the target of halving 1990 mortality rates.