Tuberculosis (TB)

Results: Detection and treatment of TB cases


Case detection rate, 1995–2002

The 4.0 million cases of tuberculosis (all forms) notified in 2002 represent 46% of the 8.8 million estimated new cases; 1.7 million new smear-positive cases account for 44% of the 3.9 million estimated (Table 7 ). In parallel with trends in case notifications, the detection rate of all TB cases has remained stable since 1995 (Figure 10 b, red points), while the detection rate of smear-positive cases has slowly increased (Figure 10 a, red points).

Thirty-five percent of all new cases, and 37% of new smear-positive cases, were detected by DOTS programmes in 2002. The detection rate achieved by DOTS programmes has been rising much faster than the overall case detection rate, and appears to have accelerated since 2000. The acceleration is more pronounced for the total number of cases notified (Figure 10 b, white points) than for smear-positives (Figure 10 a, white points). However, to reach 70% case detection by 2005, an extra 1.04 million cases (all forms), and an extra 433 000 smear-positive cases, must be found in each of the years 2003--5.

Because case detection under DOTS has increased faster than the overall rate of case detection, the proportion of notified cases that were notified by DOTS programmes has also increased. For smear-positive cases, that proportion has increased linearly since 1995, reaching 83% in 2002 (Figure 11 ). Seventy-five percent of all notified TB cases were reported under DOTS in 2002. If this trend continues, all TB cases reported to WHO by 2005 will be reported by DOTS programmes.

Figure 11: Percent of notified smear-positive cases (open circles) and of all cases (closed circles) that were notified under DOTS, 1995–2002

Although more cases are recruited to DOTS programmes each year, the case detection rate within DOTS areas (measured by the ratio of case detection to population coverage) has changed little, averaging 49% worldwide between 1996 and 2002 (Figure 12 ). There are signs of a slow rise in the HBCs, from 42% in 1996 to 51% in 2002, driven largely by improvements in India, Indonesia, Bangladesh, and the Philippines.

Figure 12: Smear-positive case detection rate within DOTS areas for high-burden countries (red) and the world (grey), 1995–2002

Smear-positive case detection rates by DOTS programmes in 2002 were lowest in the European Region (20%) and highest in the Americas (46%; Figure 13 a, Table 7 ). In the Americas, Europe and South-East Asia, significant numbers of smear-positive cases were reported from outside DOTS programmes and, in the Americas, the overall smear-positive case detection rate exceeded 70%. There were similar differences among regions in the detection rates of all TB cases (Figure 13 b). In the Americas, Europe and South-East Asia, large numbers of cases were reported from outside DOTS programmes, and the overall case detection rate approached, or reached, 70% both in the Americas and Europe.

Figure 13: Proportion of estimated new smear-positive (a) and of all estimated new cases (b) notified under DOTS (grey portion of bars) and non-DOTS (red portion of bars), 2002. Figures indicate the number of cases (in thousands) represented by each portion of each bar.
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