Comparing the results of light microscopy with the results of PCR method in the diagnosis of Plasmodium vivax.

BACKGROUND AND OBJECTIVES Although polymerase chain reaction (PCR) is a new technique in the diagnosis of malaria with very high accuracy; light microscopy is still conventional diagnostic method in Iran. In this study we checked the accuracy of light microscopy using the results of PCR as gold standard in Iran. METHODS The blood samples were collected from 124 febrile cases in Kahnooj district. The blood slides were read by microscopists, and double checked by experts in provincial referral laboratory. DNA samples were processed by PCR to amplify species-specific sequences of 18s subunit ribosomal ribonucleic acid (18ssrRNA) genes of Plasmodium vivax and P. falciparum. RESULTS The sensitivity and specificity of microscopy in the detection of Plasmodium spp infection were 77% (95% CI: 46-94%) and 100% (95% CI: 95-100%), correspondingly. Also, the estimated positive and negative predictive values were 100% (95% CI: 66-100%) and 97% (95% CI: 91-99%), respectively. INTERPRETATION AND CONCLUSION According to these results, we believe that the accuracy of light microscopy in the diagnosis of malaria in Kahnooj was acceptable. Expert micorscopists in endemic areas of Iran such as Kahnooj and available equipments in one hand and expensive PCR test on the other hand may convince that in current situation we do not have to change the diagnostic method.