Quality assessment of malaria microscopic diagnosis at the LPM-HALD of Dakar, Senegal, in 2020

Abstract Background : Following WHO guidelines, microscopy is the reference for malaria diagnosis in endemic countries. The Parasitology-Mycology laboratory (LPM) is the National Reference Laboratory and is currently undergoing ISO 15189 accreditation. In this perspective, we proceeded to laboratory verification through assessing the performance of the laboratory by confirming the reliability and the accuracy of the results obtained in accordance with the requirements of the ISO 15189 standards. This study aimed to verify the method of microscopic diagnosis of malaria at the LPM, in the Aristide Le Dantec hospital (HALD) in Dakar, Senegal. Methods: This is a validation/verification study conducted from June to August 2020. Twenty (20) microscopic slides of thick/thin smear with known parasite densities (PD) selected from the Cheick Anta Diop University malaria slide bank in Dakar were used for this assessment. Six (6) were used to assess readers' ability to determine PD and fourteen (14) were used for detection and identification of parasites. Four (4) LPM-HALD microscopists read and recorded their results on prepared sheets. Data analysis was done with Microsoft Excel 2010 software. Results: Of these twenty (20) slides read, a 100% agreement was obtained on eight (8) slides. Four (4) out of the six (6) parasite density evaluation slides obtained a concordance of less than 50%. Thirteen (13) out of the fourteen (14) identification slides obtained a concordance greater than 50%. Only one (1) identification slide obtained zero agreement from the readers. On the other hand, for species identification it was noted a score greater than 80% and the PD obtained a score between 0.20 and 0.4. Readers obtained 100% precision, sensitivity, specificity and both negative and positive predictive values. Conclusion : This work demonstrated that the microscopic method of malaria diagnosis used in the LPM/HALD are in accoradance with all the reliability required by ISO 15189.