Writing in Clinical Infectious Diseases, researchers said there is a growing need for accurate tests to identify asymptomatic malaria infections, which may aid in the elimination of the disease.
“The primary objective of the study was to determine the sensitivity and specificity of different diagnostic tests for malaria, including [rapid diagnostic tests (RDTs)], [ultrasensitive RDTs (uRDTs)], LAMP, microscopy and quantitative real-time PCR (qRT-PCR),” Dylan R. Pillai, MD, PhD, a clinician-scientist at the University of Calgary, and colleagues wrote. “The secondary objectives were to determine epidemiological characteristics for malaria and whether asymptomatic individuals harboring malaria were anemic compared to uninfected persons using highly accurate ultrasensitive diagnostics.”
In a cross-sectional study, Pillai and colleagues assessed 562 asymptomatic individuals in the Gambella region of southwest Ethiopia to establish epidemiological characteristics associated with asymptomatic malaria. Participants were tested for malaria by LAMP, ultrasensitive qRT-PCR and three RDTs, including the uRDT Alere Malaria Ag P.f (Abbott), CareStart (Accessbio) and SD Bioline Malaria Ag P.f (Abbott).
According to the findings, compared with qRT-PCR, LAMP had the highest sensitivity (92.6%; 95% CI, 86.4-96.5). The uRDT Alere test was next (33.9%; 95% CI, 25.5-43.1), followed by CareStart (14%; 95% CI, 8.4-21.5); microscopy (7.3%; 95% CI, 2.7-15.3) and SD Bioline (5%; 95% CI, 1.8-10.5).
Additionally, Pillai and colleagues compared the sensitivity of the tests for detecting Plasmodium falciparum specimens only and found the sensitivity for uRDT Alere was 50% (95% CI, 38.8-61.3), whereas SD Bioline was 7.3% (95% CI, 2.7-15.3).
According to the study, every 3.2% increase in the prevalence of asymptomatic malaria caused a decrease in hemoglobin by 1 g/dL when based on a multivariate regression analysis and compared with the gold standard, qRT-PCR. Furthermore, 4.8% deletions were observed in HRP2.
“These data show that uRDT is superior to traditional RDT in detecting asymptomatic individuals, but uRDT is still inferior to molecular techniques, with LAMP having the highest sensitivity to detect malaria compared to qRT-PCR,” Pillai and colleagues wrote. “Further studies are required to identify the optimal diagnostic test for interrupting malaria transmission in elimination studies. Longitudinal studies are also required to investigate the potential clinical benefits of treating asymptomatic malaria.”