[Analysis on the application of three methods for malaria diagnosis].

Abstract

Objective: To test the usage of microscopic examination, antigen detection(rapid dignostic test, RDT) and nucleic acid test(PCR) for detection of malaria cases.

Methods: The blood test results for malaria and suspected malaria cases during 2012-2015 were retrospectively reviewed. Taking the confirmed cases as a gold standard, the three methods were compared in aspects of diagnosis indices, specificity of identification species, and cost effectiveness.

Results: A total of 212 samples were included, each analyzed with the three methods. Based on the results of the three tests, 167(78.8%) were determined to be positive for malaria, and 45 negative (21.2%). Of the positive samples, 120(71.9%) were infected with Plasmodium falciparum,22(13.2%) with P. vivax,17(10.2%) with P. ovale, 6 (3.6%) with P. malariae, and 2(1.2%) with mixed infections. The method of PCR had the highest diagnostic efficiency (96.2%,204/212), followed by RDT (93.2%,192/206; P > 0.05 vs. PCR) and the microscopic method (88.2%,187/212; P < 0.05 vs. RDT and PCR). Similarly, the PCR method had the highest overall coincidence rate to the confirmed cases (95.3%,202/212), followed by RDT (93.2%,192/206) and microscopy (88.2%,187/212; P < 0.05 vs. PCR). As to the identification specificity among species, the PCR method(95.6%, 43/45) was superior to microscopy (91.1%, 41/45; P > 0.05 vs. PCR) and RDT (68.9%, 31/45; P < 0.05 vs. PCR). As to the identification of a particular species (P. falciparum), RDT performed best (100%,116/116), followed by PCR (93.3%,112/120) and microscopy (84.2%,101/120). Based on the comprehensive evaluation on 14 indicators including if it is a diagnostic criterion, equipment and technical requirement, diagnostic performance, time cost, and the need of technical training and promotion, we found that the RDT method had the highest score(37 of 42), while microscopy and PCR were scored 26 and 27, respectively.

Conclusion: Under the falciparum malaria-dominated epidemiological situation, PCR and RDT show a higher detection efficiency, PCR and microscopy perform better in species identification, and RDT has the highest cost-effectiveness.