Case Study

Namibia – Occurrence of asymptomatic TB in active case finding campaign with CAD4TB

CAD4TB platform closeup

Asmptomatic TB is rapidly emerging as a state that warrants attention. The study aimed to determine the proportion of subclinical TB among newly bacteriologically positive TB patients using three definitions.

Community TB screening campaigns

Voluntary TB screening was conducted in hard-to-reach and underserved communities.

Symptom screening and X-ray

Participants were screened for symptoms and received chest X-rays analyzed with CAD4TB.

AI-based triage

A CAD4TB threshold score of 50 was used to identify presumptive TB cases.

Molecular confirmation

Individuals with positive screening results were offered Xpert MTB/RIF Ultra testing.

Result

Among 18,662 participants,

15 ,047
had radiographs
2 ,806
had sputum results
9 7 cases
bacteriologically confirmed
14 .4% of patients
were negative for any of the four symptoms
  • The proportion of subclinical TB was 18.5% among individuals without any cough, 41.2% among those without prolonged cough, and 14.4% among those negative on the WHO four-symptom screen.
CAD4TB platform closeup
Conclusion
  • Subclinical TB is a significant issue. Using prolonged cough to screen for symptoms misses almost half of TB cases.
  • Using the W4SS or a more inclusive screening regimen defines subclinical TB that misses the least number of cases.

REFERENCE: Ruswa, N. et al (2024, November 12-16). Occurrence of subclinical TB in a community active case finding campaign [Presentation]. The Union World Conference on Lung Health, Bali, Indonesia.