Present outlooks on the prevalence of minimal and subclinical tuberculosis and current diagnostic tests: A systematic review and meta-analysis

Background

Tuberculosis (TB) is a major global health issue, particularly in its minimal and subclinical forms, which often go undetected and contribute to transmission. Accurate prevalence assessment of these forms and the effectiveness of diagnostic tests are crucial for improving TB control, especially in high-risk populations such as those with HIV.

Objectives

This study aimed to determine the prevalence of minimal and subclinical TB and evaluate the positivity rates of current diagnostic tests. Methods: We conducted a meta-analysis of studies published from January 2000 to December 2022. Prevalence rates and diagnostic test results, including sputum culture, smear microscopy, TST/IGRA, and chest X-ray, were analyzed, with pooled prevalence calculated and comparisons made between geographic regions.

Results

Minimal TB prevalence ranged from 0.9 % to 22.9 % in the general population, while subclinical TB prevalence was 0.05 % to 0.64 %, and 1.57 % to 14.63 % among individuals with HIV. The overall pooled prevalence of minimal TB was 7 % (95 % CI: 5–9 %), with higher rates in Asia (8 %, 95 % CI: 5–12 %) compared to Africa (6 %, 95 % CI: 4–8 %). Subclinical TB had a pooled prevalence of 0.2 % (95 % CI: 0.2–0.3 %) overall and 52 % (95 % CI: 46–58 %) among TB cases, with higher rates in Asia (60 %) compared to Africa (44 %). Diagnostic test positivity was 77 % (sputum culture), 15 % (smear microscopy), 64 % (TST/IGRA), and 53 % (chest X-ray).

Conclusions

This study reveals significant variability in the prevalence of minimal and subclinical TB. The findings highlight the need for improved diagnostic methods to reduce undetected cases, especially in high-risk populations.