Did an ultrasensitive malaria test detect more infections than a conventional test in Kisangani?

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An ultrasensitive rapid diagnostic test (usRDT) was recently developed to improve detection of low-density Plasmodium falciparum infections. Its diagnostic performance had not been evaluated in the Democratic Republic of Congo (DRC). This study aimed to assess its performance for malaria diagnosis under field conditions among asymptomatic people in Kisangani, northeastern DRC.

The community-based cross-sectional study included 312 asymptomatic Kisangani residents from June to August 2022. Capillary blood was collected by finger prick for microscopic examination of thick and thin blood films, rapid diagnostic tests, and nested polymerase chain reaction (PCR). Researchers used Alere™ Malaria Ag P.f usRDT and conventional RDT (cRDT/SD Bioline Malaria Ag P.f) kits to detect Plasmodium histidine-rich protein 2 (HRP2) antigen as a proxy for the presence of P. falciparum. They compared the usRDT’s diagnostic performance with cRDT, microscopy and PCR.

The prevalence of asymptomatic P. falciparum malaria was 40.4% by cRDT, 42.0% by microscopy, 47.1% by usRDT and 54.2% by PCR. Using PCR as the reference, the usRDT had 87.0% sensitivity (95% CI 81.4–91.7) and 100.0% specificity (95% CI 97.5–100.0); the cRDT had 74.6% sensitivity (95% CI 67.3–80.9) and 100% specificity (95% CI 97.1–100.0). Using microscopy as the reference, the usRDT had 96.9% sensitivity (95% CI 92.4–99.2) and 89.0% specificity (95% CI 83.5–93.1); the cRDT had 96.2% sensitivity (95% CI 92.3–98.7) and 100% specificity (95% CI 97.9–100.0).

The researchers concluded that the usRDT performed better, with higher sensitivity than the cRDT currently used as a point-of-care test. Further research is needed to assess access to usRDTs and their cost-effectiveness for malaria surveillance.