Malaria Rapid Diagnostic Test Evaluated At Point-Of-Care

For over a decade, the development of malaria rapid diagnostic tests (RDTs) has enabled reliable biological diagnostic testing in all situations where previously only clinical diagnosis was available. These RDTs are generally considered as point-of-care tests.

Most of the studies assessing the performance of malaria RDTs are conducted by trained scientific teams that are not representative of the classical end-users, who are typically unskilled in traditional laboratory techniques for diagnosing malaria. Consequently, only the basic performance of malaria RDTs is evaluated and information regarding their overall performance when they are used by the traditional end-users is lacking.

Scientists at the Institut Pasteur du Cambodge (Phnom Penh, Cambodia) tested three types of sample (negative, low positive, high positive) in replicates of four, corresponding to a panel of 20 aliquots, as followed: one negative sample, one low positive sample at 200 parasites of Plasmodium falciparum/μL, one low positive sample at 200 parasites of P. vivax/μL, one high positive sample at 2,000 parasites of P. falciparum/μL and one high positive sample at 2,000 parasites of P. vivax/μL. Twenty end-users with four different profiles in seven communes in Kampot Province (Cambodia) were selected.

The ready-to-use cassette device the VIKIA Malaria Ag Pf/Pan (IMACCESS/bioMérieux; Lyon, France) was the RDT used. This test is based on immunochromatographic technology for detecting P. falciparum and other species of Plasmodium (P. vivax, P. malariae, and P. ovale). The team performed a quality control assessment of the set of the 20 aliquots at three different times (at the start, middle and end of the study), to confirm the good quality of the aliquots distributed to the users and to verify that no degradation occurred during transport or storage that could affect the expected results.

All results obtained by the end-users were consistent with the expected results, except for the low positive (200 parasites/μL) P. vivax aliquot (35% of concordant results). No significant difference was observed between the different end-users. End-user interviews evaluating ease-of-use and ease-of-reading of the VIKIA Malaria Ag Pf/Pan kit recorded 159 positive answers and only one negative answer. Out of 20 end-users, only one considered the test was not easy to perform with the support of the quick guide.

The authors concluded that the performance of the VIKIA Malaria AgPf/Pan rapid test performed by traditional end-users in field conditions is similar to those obtained by a trained scientific team, and that VIKIA Malaria AgPf/Pan can be considered as a point-of-care test. In addition, the protocol designed for this study, using well-characterized and calibrated blood samples could be used systematically in parallel to conventional evaluation studies to determine the performance of malaria RDTs in field conditions. The study was published on March 14, 2015, in the Malaria Journal.

Related Links:
Institut Pasteur du Cambodge 
IMACCESS/bioMérieux