What is the limit to case detection under the DOTS strategy for tuberculosis control?

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Global Health Policy

Background:

• The World Health Organization's Directly Observed Treatment Short-course (DOTS) strategy was widely adopted for tuberculosis (TB) control.
• Despite widespread adoption, global TB case detection rates remained a concern, with only 27% of estimated smear-positive patients notified in 2000.

Purpose of the Study:

• To analyze the progress of TB case detection under the DOTS strategy up to the year 2000.
• To forecast future case detection rates towards the global target of 70%.

Main Methods:

• Analysis of annual reports on DOTS geographical coverage and case notifications.
• Focus on 22 high-burden countries (HBCs) accounting for approximately 80% of global TB cases.

Main Results:

• Case detection rates within DOTS areas in the 22 HBCs remained stagnant at 40-50%, despite expanding geographical coverage.
• This detection fraction mirrors the global notification rate via public health systems.
• Three-quarters of undetected smear-positive cases are concentrated in six countries: India, China, Indonesia, Nigeria, Bangladesh, and Pakistan.

Conclusions:

• The DOTS strategy's effectiveness in increasing case detection is limited by reliance on traditional public health reporting systems.
• Significant improvements in case finding, management, and routine surveillance are crucial to bridge the gap towards the 70% global TB detection target.
• Enhanced national TB incidence estimates are vital, particularly through reinforced surveillance systems.