PA-69 Performance of ultra-sensitive malaria rapid diagnostic test to detect plasmodium falciparum infection in pregnant women in Kinshasa, the Democratic Republic of the Congo

Abstract

<h3>Background</h3> Low peripheral parasitemia caused by sequestration of Plasmodium falciparum in the placenta hampers the diagnosis of malaria in pregnant women, leading to microscopy or conventional rapid diagnostic tests (co-RDTs) false-negative results. Although mainly asymptomatic, maternal malaria remains harmful to pregnant women and their offspring in endemic settings and must be adequately diagnosed. Ultra-sensitive RDTs (uRDTs) are thought to be more sensitive than co-RDTs, and their diagnostic performance was assessed in the present study in pregnant women living in Kinshasa, a stable malaria transmission area in the Democratic Republic Congo. <h3>Methods</h3> To assess and compare the performances of both co-RDTs and uRDTs, 497 peripheral blood samples were tested using microscopy and quantitative polymerase chain reaction (qPCR) as the index and the reference tests respectively. The agreement between uRDT, co-RDT, microscopy and qPCR was determined by Cohen’s Kappa test. <h3>Results</h3> The median parasite density by qPCR was 292 p/μL of blood [IQR 292 (49.7–1,137)]. Using qPCR as the reference diagnostic test, microscopy was the least sensitive test [55.7% (95% CI: 47.6–63.6)], followed by co-RDT [81.7% (95%CI:74.7–87.3)] and uRDT [88% (95% CI:81.9–92.6)]. The corresponding specificity was respectively: 98.5% (95% CI:96.6–99.5), 95.2% (95% CI:92.5–97.2) and 94.4% (95% CI:91.4–96.6). The agreement between qPCR and uRDT was almost perfect (kappa=0.82). For parasite density (qPCR) below 100p/µL, the sensitivity of co-RDT was 62% (95%CI:47.1–75.3) compared to 68% (95%CI:53.3–80.4). Between 100 and 200p/µL, the sensitivity of co-RDT tended to be lower compared to uRDT: 89.4%(95%CI:66.8–98.7) versus 100%(95%CI:82.3–100) for uRDT. In both cases, microscopy was lower, with 20% (95%CI:10–33.7) and 47.3% (95%CI:24.4–71.1) respectively. <h3>Conclusion</h3> uRDT tended to be more sensitive than co-RDT in the detection of malaria in pregnant women. Therefore, it has the potential to improve malaria management in pregnant women. Microscopy shows poor performance for the diagnosis of malaria in pregnancy.