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.
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.
ABSTRACT
In vitro drug susceptibility testing of <I>Plasmodium falciparum</I> must be conducted immediately after collecting a sample of the patient‘s blood; otherwise the parasites may weaken and the culture fail. Collecting blood samples from individuals in areas far from the field station or clinic where in vitro testing is conducted requires a reliable method of sample preservation during transportation. We examined and compared three different methods used to preserve blood samples in endemic areas in the Philippines. The three methods are as follows: the on-site method (test is conducted soon after blood sampling), flask culture method (sample is taken to the laboratory in a culture flask with medium) and EDTA tube method (sample is taken to the laboratory in a blood collection tube). The WHO <I>in vitro</I> micro-test for susceptibility of <I>P. falciparum</I> to chloroquine was performed using an AnaeroPack® system and a portable thermostat incubator. Evaluation of the three methods was based on schizont maturation, ease of handling, and risk of contamination during the test. The on-site and flask culture methods, but not the EDTA tube method, were effective for keeping the parasites viable. Furthermore, schizont maturation appeared better with the flask method than with the on-site method, especially in the control wells (drug-free wells). In addition, it was easier to perform the flask method than the on-site method. No contamination was observed using any of the methods. The results of the study suggest that the flask culture method is the most effective and useful way to preserve blood samples for the in vitro test and, moreover, that it aids in providing detailed field evidence of drug-resistant malaria.