Comparative evaluation of traditional and molecular diagnostic methods for malaria: An analysis of performance

As we edge closer to the eradication of malaria, several methods for detecting Plasmodium species have been developed, including peripheral blood smear examination (PBS), rapid diagnostic tests (RDTs), serological evaluations, fluorescent microscopy, polymerase chain reactions (PCRs), fluorescent in situ hybridization, and flow cytometry. The suitability of these tools for routine diagnosis requires evaluation, considering both their diagnostic accuracy and cost-effectiveness.

Our study compared four diagnostic techniques for malaria: PBS, quantitative buffy coat (QBC), RDT, and PCR. We used PCR as the benchmark standard and statistically assessed the performance of PBS, QBC, and RDT against PCR in detecting malaria. Adopting a prospective observational approach, we collected blood samples from 117 patients exhibiting the symptoms suggestive of malaria.

The findings from our study showed that PBS had a positivity rate of 93.4%, with a 95% confidence interval (CI) of 0.881-0.987, indicating reliable results for a similar population. The QBC assay demonstrated an elevated positivity rate of 96.7% with a solid 95% CI of 0.930-1.000. Although the RDT had a slightly lower rate of 92.4%, it still delivered dependable results, presenting a significant 95% CI of 0.868-0.980, ensuring a robust diagnostic performance compared to PCR.

PCR is a reliable test when the identification of the specific species is inconclusive. Conversely, the commonly used PBS occasionally overlooks positive malaria cases due to the specialized skills needed for accurate reading. The cost-effective RDT is feasible for field operations without the need for expert knowledge. However, it fails to differentiate between old and new infections. Meanwhile, the QBC test, known for its sensitivity and speed, can be consistently employed for malaria diagnosis in a tertiary care settings.