Table 1

Comparison of EVD diagnostic systems

Assay system
CategoryRT-LAMP* (Nagasaki University-Toshiba Medical Systems Corp, Japan)RDT† (ReEBOV Antigen Rapid Test, US)Reference: rRT-PCR‡
Validated sample number in study100 (for field validation study)293 (WHO independent evaluation by 2 ref. laboratories)
106 (for field validation study)
Widely used as the WHO benchmark assay
Characteristics of target populationConakry and its surrounding prefectures in GuineaSierra Leone
Samples validated for testingFresh/frozen blood, plasma (44 samples tested), oral swab (56 samples tested)Fresh venous whole blood (147) frozen specimen(146) for WHO evaluation
Fresh/frozen whole blood (fingerstick, venous) for field validation study
Plasma collected in EDTA§, cell-free body-fluids, swab washes
Reference PCR test for validation studyLightMix Modular Ebola Virus Zaire 2014 (TIB Molbiol, Germany)
SmartCycler II system (Cepheid, USA)
RealStar Filovirus Screen RT-PCR Kit 1.0
Altona Diagnostics (GmbH, Germany)
SmartCycler II system (Cepheid, USA)
Sensitivity (%)100 (92.5–100)¶100 (92.1–100)**
100 (87.7–100)††
Specificity (%)100 (93.3–100)¶92.2 (88.0–95.3)**
92.2 (83.8–97.1)††
Positive predictive value (%)100 (92.5–100)¶71.4 (58.7–82.1)**
82.4 (65.5–93.2)††
97.3 (90.6–9.7)‡‡
Negative predictive value (%)100 (93.3–100)¶100 (98.3–100)**
100 (94.9–100)††
73.3 (66.9–79.8)‡‡
Detected Ct* range shown in study17.1–37.5 (≓ 5.3×108–1.9×104 RNA copies/mL)15.9–26.3 (median 21.3 (19.2–23.4))13.4–33.0 (median 21.1 (19.1–24.5))
Probable limit of Ct*** value for detection2.0×105 RNA copies/mL2.11×108 RNA copies/mL (WHO evaluation)Limit of detection not assessed by the WHO during EUAL assessment.
1PFU (approximately 3400 copies) of ZEBOV/mL plasma (FDA EUA)
Throughput (time to results)<1 hour including the platform assay <15 min for positive (9–22.5 min)15–25 min4–6 hours for negative, less for positive
Maximum number of samples processed/day72 samples/system (6 samples×12 run/8 hours)60–100 specimens/operatorApproximately 50 specimens/system
Transport and stage condition (for reagents)Non–cold chain system in development (at least 6-month reagent shelf life at below 35°C)Cold chain required (2–8°C, not frozen, 6 months stable)Cold chain required (−2°C, 9-month reagent shelf life)
Power supplyOperational by battery charge (1.5 hours operational by 1 time charge=1 day operation by 4 time charge)No electricityElectricity only
Portability1.75 kgNegligible>10 kg (laptop-PC)
  • *RT-LAMP, reverse transcription—loop mediated amplification method.

  • †RDT, rapid diagnostic test.

  • ‡rRT-PCR, real-time reverse transcription-PCR.

  • §EDTA, ethylenediamine-tetraacetic acid.

  • ¶The indicated results were from the RT-LAMP test with the primers for the untranscribed trailer region with 100 samples.26

  • **The indicated results were obtained by the WHO evaluation test at the reference laboratory with 277 samples (whole blood).17

  • ††The indicated values were obtained by the field validation study with 105 fingerstick samples.17

  • ‡‡The indicated values were obtained by the field validation study with 176 samples (whole blood).18

  • ***Ct, cycle threshold.

  • EVD, Ebola virus disease; EUA, emergency use authorisation; FDA, Food and Drug Administration.