Contribution of real-time PCR to Plasmodium species identification and to clinical decisions: a nationwide study in a non-endemic setting

Treatment choice for patients with malaria in Israeli hospitals is based on microscopy and rapid diagnostic tests (RDTs). Here, we demonstrate the cumulative value of real-time polymerase chain reaction (PCR) in optimizing the treatment of malaria. Between January 2009 and December 2015, 451 samples from 357 patients were tested in our laboratory using a real-time PCR assay. Hospital laboratory results (without real-time PCR) were compared to those obtained in our laboratory. A total of 307 patients had a malaria-positive laboratory finding in the hospital. Out of those, 288 were confirmed positive and 19 negative using real-time PCR. Two negative hospital results were found to be positive by real-time PCR. More specifically, of 153 cases positive for Plasmodium falciparum by real-time PCR, only 138 (90%) had been correctly identified at the hospitals. Similarly, 66 (67%) of 99 cases positive for P. vivax, 2 (11%) of 18 cases positive for P. ovale, and 3 (30%) of 10 cases positive for P. malariae had been correctly identified. Of 10 cases of mixed infection, only one had been identified as such at the hospital. Thus, real-time PCR was required for correct identification in 81 (28%) out of 290 positive cases. In 52 (18%) of those, there was an erroneous categorization of relapsing versus non-relapsing parasites. In a nationwide study, we found that the use of real-time PCR is definitely beneficial and may change the decision regarding the choice of treatment.