Effects of Buffer Substitution on Rapid Diagnostic Tests for Malaria Diagnosis

Résumé

Abstract Background: Malaria rapid diagnostic tests (mRDTs) detect Plasmodium antigens by antibody-antigen interactions on a nitrocellulose test strip/cassette. While this has proven useful and can detect Plasmodium spp. in about 15-20 mins, false positives and negatives are known limitations of any diagnostic test and mRDTs are no exception. Buffer substitution in RDTs is one phenomenon known to cause such incorrect results even though its extent in practice on the field is unknown. Aim: This study sought to examine the effects of substituting a designated buffer with other liquids on malaria RDTs.Methods: The study was a cross-sectional analytical study that recruited 125 suspected malaria patients from Tafo Government Hospital in Kumasi, Ghana from February to March, 2022. 5ul of blood was taken using a lancet and a thick smear was prepared, stained and examined under light microscopy for malaria parasites. Part of the blood samples were also used concurrently to perform RDTs (using SD Bioline malaria RDT test kit) but with four different buffers separately (designated RDT buffer, 0.9% saline, distilled water and Hightop HBsAg test buffer). Results: Majority of the participants were in their 20s (21.6%) or 30s (20.8%). The least age group recorded were from 40-49 years (9.6%). More than two-thirds of the participants were females (69.6%). The common symptoms recorded were fever (29.6%), headache (28.0%), general body pain (28.0%) and malaise (23.2%). When the RDTs with the different buffers were compared to microscopy, SD Bioline buffer was 90.6% sensitive, 95.7% specific. When distilled water was used as a substitute buffer, it gave a 100% specificity but was less sensitive (68.8%). Similarly, 0.9% saline and HBsAg buffer were specific but less sensitive. Cohen’s Kappa (k) for using SD Bioline RDT buffer, 0.9% saline, distilled buffer and HBsAg were significantly in agreement at 85.4%, 61.7%, 76.6%, and 73.1% with light microscopy respectively (p < 0.0001). Conclusion: Buffer substitution in malaria rapid diagnostic testing reduces the test sensitivity of the kit.

Citer ce document

Accès au document

Ce document est hébergé sur son dépôt institutionnel d'origine.

Auteur(s)

Statistiques

Consultations : 1

Téléchargements : 0