Evaluation of AFB Microscopy in Diagnosing Pulmonary Tuberculosis: Performance Assessment of Laboratories in Zoba-Maekel, Eritrea

AbstractBackground: Acid-Fast Bacillus (AFB) microscopy remains the cornerstone for diagnosing pulmonary tuberculosis (TB) in resource-limited settings like Eritrea. Despite WHO guidelines targeting a 70% detection rate of new smear-positive cases, Eritrea lags significantly behind.Methods: A cross-sectional qualitative study was conducted across six laboratories in Zoba-Maekel. The study involved blind rechecking of 325 previously stained slides, panel testing using standardized samples, and support supervision using a WHO-approved evaluation checklist.Results: The case detection rate (CDR) remained below WHO estimates (14%–40% vs. 70%). In blind rechecking, two minor errors (quantification) were observed with no major diagnostic discrepancies. Panel testing showed variable performance; Orrotta N.R.H. scored 10/10 while others, notably Semenawi Asmara, scored as low as 6/10. Support supervision revealed infrastructural gaps, inadequate training, substandard documentation, and poor slide storage practices.Conclusion: Laboratory performance is borderline acceptable with significant room for improvement. Enhancing infrastructure, regular training, and adopting newer diagnostic technologies are essential to improving TB detection in Eritrea.