Comparison of the diagnostic values of microscopic examination and nested PCR for optimum malaria diagnosis in Upper Myanmar

초록

Accurate diagnosis of Plasmodium infection is crucial for prompt malaria treatment and surveillance. Although the diagnostic value of microscopic examination for malaria has been questioned, it has been widely considered as the gold standard in most part of malaria endemic regions, including Myanmar. The aim of this study was to evaluate the performance of nested polymerase chain reaction (PCR) compared to microscopic examination as a means of detecting Plasmodium species in Upper Myanmar. A total of 823 suspected malaria cases were examined with microscopic examinations and 172 cases (20.9%) were confirmed as positive for malaria infection. Re-evaluation of the samples by species-specific nested PCR analysis revealed that the agreement between microscopic examination and nested PCR was 86.6% (149/172). In 23 samples (13.4%), the microscopic examinations either misdiagnosed the infected Plasmodium species, or did not detect mixed infections with different Plasmodium species. Meanwhile, nested PCR successfully detected P. malariae and P. ovale infections, which were mostly missed in microscopic examination. The nested PCR method is more reliable than conventional microscopic examination for the diagnosis of malaria infections, and this is particularly true in cases of mixed infections. Given the observed higher sensitivity and specificity of nested PCR, the molecular method holds enormous promise in malaria diagnosis and species differentiation, and can be applied as an effective monitoring tool for malaria surveillance in Myanmar.