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J Clin Microbiol. 2018 Jul 26;56(8). pii: e00565-18. doi: 10.1128/JCM.00565-18. Print 2018 Aug.

Operational Performance of a Plasmodium falciparum Ultrasensitive Rapid Diagnostic Test for Detection of Asymptomatic Infections in Eastern Myanmar.

Author information

1
Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand jordi.landier@ird.fr.
2
Institut de Recherches pour le Développement (IRD), Aix Marseille Université, INSERM, SESSTIM, Marseille, France.
3
Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.
4
PATH, Diagnostics Program, Seattle, Washington, USA.
5
Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
6
Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.

Abstract

In the Greater Mekong Subregion in Southeast Asia, malaria elimination strategies need to target all Plasmodium falciparum parasites, including those carried asymptomatically. More than 70% of asymptomatic carriers are not detected by current rapid diagnostic tests (RDTs) or microscopy. An HRP2-based ultrasensitive RDT (uRDT) developed to improve the detection of low-density infections was evaluated during prevalence surveys within a malaria elimination program in a low-transmission area of eastern Myanmar. Surveys were conducted to identify high-prevalence villages. Two-milliliter venous blood samples were collected from asymptomatic adult volunteers and transported to the laboratory. Plasmodium parasites were detected by RDT, uRDT, microscopy, ultrasensitive qPCR (uPCR), and multiplex enzyme-linked immunosorbent assay (ELISA). The sensitivity, specificity, and predictive positive and negative values of RDT and uRDT were calculated compared to uPCR and ELISA. Parasite and antigen concentrations detected by each test were defined using uPCR and ELISA, respectively. A total of 1,509 samples, including 208 P. falciparum-positive samples were analyzed with all tests. The sensitivity of the uRDT was twofold higher than that of RDT, 51.4% versus 25.2%, with minor specificity loss, 99.5% versus 99.9%, against the combined reference (uPCR plus ELISA). The geometric mean parasitemia detected by uRDT in P. falciparum monospecific infections was 3,019 parasites per ml (95% confidence interval [95% CI], 1,790 to 5,094; n = 79) compared to 11,352 parasites per ml (95% CI, 5,643 to 22,837; n = 38) by RDT. The sensitivities of uRDT and RDT dropped to 34.6% and 15.1%, respectively, for the matched tests performed in the field. The uRDT performed consistently better than RDT and microscopy at low parasitemias. It shows promising characteristics for the identification of high-prevalence communities and warrants further evaluation in mass screening and treatment interventions.

KEYWORDS:

Plasmodium falciparum; asymptomatic infection; low density parasitemia; low transmission setting; malaria; rapid tests; ultrasensitive RDT

PMID:
29898998
PMCID:
PMC6062819
DOI:
10.1128/JCM.00565-18
[Indexed for MEDLINE]
Free PMC Article

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