Biosensor as a molecular malaria differential diagnosis.

BACKGROUND: In malaria diagnosis, specific gene identification is required in cases with subclinical infection or cases with mixed infection. This study applied the biosensor technology based on quartz crystal microbalance (QCM) to differentially diagnose the most common and severe malaria, Plasmodium falciparum and Plasmodium vivax. METHOD: The QCM surface was immobilized with malaria biotinylated probe. Specific DNA fragments of malaria-infected blood were amplified. Hybridization between the amplified products and the immobilized probe resulted in quartz frequency shifts which were measured by an in-house frequency counter. Diagnostic potency and clinical application of the malaria QCM were evaluated. RESULT: The malaria QCM could differentially diagnose blood infected with P. falciparum from that infected with P. vivax (p-value<0.05). No cross reaction with human DNA indicated the QCM specificity. Clinical application was evaluated using 30 suspected samples. Twenty-seven samples showed consistent diagnosis of the QCM with microscopy and rapid diagnosis tests (RDTs). Three samples reported "no malaria found" by microscopy showed P. falciparum infection by both QCM and the RDTs. CONCLUSION: The malaria QCM was developed with high accuracy, specificity, sensitivity, stability and cost-effectiveness. It is field applicable in malaria endemic area and might be a promising point of care testing.