Accuracy of SD Malaria Ag P.f/Pan® As A Rapid Diagnosis Test of Malaria in French Amazonia

Abstract

\n BackgroundFrench Guiana (FG) is, with Mayotte island, one of the two French overseas territories where malaria is still endemic. Ten years ago, French health authorities implemented a strategy to eradicate malaria disease in the region. The current incidence rate is 0,74‰ inhabitants, and Plasmodium Vivax is widely predominating even though Plasmodium Falciparum is still present due to imported cases, mainly from the Africa continent. In FG, RDT (SD Malaria Ag P.f/Pan®) test is based on detection of pan-pLDH, PfHRP2, and PfHRP3 antigens. While, in South America, the share of deletion of PfHRP2 gene is significantly increasing. So, we wondered if RDTs remained reliable in this context.MethodsOur study is a retrospective analysis conducted over four years and analyzed 12880 rapid diagnosis tests (RDTs) whose result was compared with Blood Film Tests (BFTs) sampled for malaria diagnosis.ResultsThe global assessment of the diagnosis accuracy of RDT in the diagnosis of malaria shows PPV (Positive Predictive Value) and NPV (Negative Predictive Value) more than 95%, except for PPV of RDT in the diagnosis of malaria to P falciparum (88%). Overall, the concordance rate between RDT and BFT (positive/positive; negative/negative) was 99.5%. The PPV of the RDT in the follow-up of patients diagnosed with P falciparum was the lowest during the 28 first days after diagnosis. The PPV of the RDT in the follow-up of patients diagnosed with P vivax was the lowest during the 21 first days after diagnosis. The global sensitivity of SD Malaria Ag P.f/Pan® test was, on average, 96% (88.2 – 1) for P falciparum and 93% (90.6 – 94.2) for P vivax. The global specificity was high, with a rate of 99.8% (99.5 – 1) for all species included.ConclusionSD Malaria Ag P.f/Pan® is still a reliable rapid test used for the first-line diagnosis in remote healthcare centers. The test reading should be nuanced by the recent medical history of patients and the date of arrival in FG. RDT result has always to be confirmed by BFT that is still the gold standard for the malaria diagnosis. FG is still a PfHRP2 gene deletion-free area.