Performance of Rapid Diagnostic Tests for <i>Plasmodium ovale</i> Malaria in Japanese Travellers

ABSTRACT

Background: Rapid diagnostic tests (RDTs) have widely been used in the diagnosis of malaria. Although the effectiveness of RDTs for malaria has previously been described in many reports, the low performance of RDTs particularly for <i>Plasmodium ovale</i> malaria in travellers have rarely been reported. Methods: This was retrospective cohort study conducted among Japanese travellers who were diagnosed with malaria at the National Center for Global Health and Medicine between January 2004 and June 2013. Diagnosis of malaria by microscopic examination, RDT, and polymerase chain reaction were performed for all the patients. The RDTs used in our study were Binax NOW Malaria (Binax Inc., Scarborough, Maine, USA) (BN) and SD Malaria Antigen Pf/Pan (Standard Diagnostics Inc., Korea) (SDMA). We compared the sensitivity of the RDTs of <i>P. ovale</i> malaria with that of <i>Plasmodium vivax</i> malaria. Results: A total of 153 cases of malaria were observed, of which 113 patients were Japanese travellers. Nine patients with <i>P. ovale</i> malaria and 17 patients with <i>P. vivax</i> malaria performing RDTs were evaluated. The overall sensitivity of RDTs for <i>P. ovale</i> malaria was 22.2% and that for <i>P. vivax</i> malaria was 94.1% (P < 0.001). The sensitivity of SDMA for <i>P. vivax</i> malaria was 100% and that for <i>P. ovale</i> malaria was 50%. The sensitivity of BN for <i>P. vivax</i> malaria was 90.0%; however, it was unable to detect the cases of <i>P. ovale</i> malaria. Conclusions: The sensitivity of RDTs was not high enough to diagnose <i>P. ovale</i> malaria in our study. Thus, microscopic examination is indispensable not to overlook <i>P. ovale</i> malaria.