Global Tuberculosis Report -- 2012.pdf

FIGURE 2.7Estimated TB incidence rates by WHO region, 1990–2011. Regional trends in estimated TB incidence rates (green)and estimated incidence rates of HIV-positive TB (red). Shaded areas represent uncertainty bands.400Africa80The Americas150Eastern Mediterranean30060100200401002050Rate per 100 000 population per year0Europe800250South−East Asia0200Western Pacific60200150150401001002050500001990 1995 2000 2005 20111990 1995 2000 2005 2011 1990 1995 2000 2005 2011able for countries with a high burden of TB (see Section2.5.2), TB prevalence can be estimated only indirectly inmost countries.There were an estimated 12 million prevalent cases(range, 10 million–13 million) of TB in 2011 (Table 2.1),equivalent to 170 cases per 100 000 population (Table 2.2).The prevalence rate has fallen by 36% globally since 1990.Current forecasts suggest that the Stop TB Partnership’starget of halving TB prevalence by 2015 comparedwith a baseline of 1990 will not be met worldwide (Figure2.3). Regionally, prevalence rates are declining in all ofWHO’s six regions (Figure 2.10). The Region of the Americashalved the 1990 level of TB prevalence by around2005, well in advance of the target year of 2015, andthe Western Pacific Region is close to doing so. Achievingthe 50% reduction target by 2015 appears feasible inthe European and South-East Asia regions, but not in theAfrican and Eastern Mediterranean regions.2.3 MortalityMortality caused by TB can be directly measured if anational VR system of high coverage with accurate codingof causes of death according to the latest revision ofthe international classification of diseases (ICD-10) is inplace. Sample VR systems can provide an interim solution,and mortality surveys can sometimes be used toobtain direct measurements of TB deaths in countrieswith no VR system. In the absence of VR systems ormortality surveys, TB mortality can be estimated as theproduct of TB incidence and the case fatality rate, or fromecological modelling based on mortality data from countrieswith VR systems.Until 2008, WHO estimates of TB mortality used VRdata for only three countries. This was substantiallyimproved to 89 countries in 2009, although most of thesecountries were in the European Region and the Region ofthe Americas, which account for only 8% of the world’sTB cases. The use of sample VR data from China and surveydata from India for the first time in 2011 enabled afurther major improvement to estimates of TB mortal-16 GLOBAL TUBERCULOSIS REPORT 2012