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

ABSTRACT

Background: Rapid diagnostic tests (RDTs) are used widely in the diagnosis of malaria. Although the effectiveness of RDTs for malaria has been described in many previous studies, the low performance of RDT particularly for <i>Plasmodium ovale</i> malaria in traveller has rarely been reported. Methods: This was a retrospective cohort study conducted on Japanese travellers diagnosed with malaria at the National Center for Global Health and Medicine between January 2004 and June 2013. The diagnosis of malaria was confirmed by microscopic examination, RDT, and polymerase chain reaction in all 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 to <i>P. ovale</i> malaria and <i>Plasmodium vivax</i> malaria. Results: A total of 153 cases of malaria were observed, 113 of which were found among Japanese travellers. Nine patients with <i>P. ovale</i> malaria and 17 patients with <i>P. vivax</i> malaria undergoing RDTs were evaluated. The overall sensitivity of RDTs for <i>P. ovale</i> malaria and <i>P. vivax</i> malaria was 22.2% and 94.1%, respectively (P < 0.001). The sensitivity of SDMA for <i>P. ovale</i> malaria and <i>P. vivax</i> malaria was 50% and 100%, respectively. The sensitivity of BN for <i>P. vivax</i> malaria was 90.0%, but it was ineffective in detecting 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. In order not to overlook <i>P. ovale</i> malaria, therefore, microscopic examination is indispensable.