Résumé
Lors de l’épidémie de maladie à virus Ebola qui a frappé l’Afrique de l’Ouest en 2014, l’OMS a souligné le besoin de tests de diagnostic rapide (TDR), simples d’emploi, aisément déployables et facilement utilisables sur le terrain. Le TDR (Lateral Flow Assay) Ebola eZYSCREEN® a été développé dans ce contexte d’urgence avec des anticorps monoclonaux dirigés contre la glycoprotéine d’enveloppe du virus. Deux versions ont été industrialisées, l’une pour des échantillons de sang total et l’autre pour des échantillons de sérum et de plasma. Ces deux versions ont une limite de détection analytique de 105 pfu/ml, la stabilité est au minimum de 393 jours à 30 °C et 120 jours à 45 °C. Une étude de validation, indépendante, non rétrospective, a été réalisée en situation réelle, pendant la flambée épidémique à Conakry et au centre de traitement Ebola de Coyah sur 144 patients. Les sensibilités et spécificités des TDR sont respectivement de 65,3 et 98,9 % sur sang total et de 74,5 et 100 % sur sérum. Les performances observées avec la version sang total sont à prendre avec précaution en raison de contraintes logistiques, dues au contexte particulier de cette crise Ebola, qui ont compliqué la réalisation de cette étude, avec notamment un délai moyen de trois jours entre le prélèvement et la réalisation des tests, ce qui est en dehors des spécifications. Néanmoins, ce test de terrain, simple d’emploi, facilement déployable, qui ne nécessite pas, contrairement aux tests de laboratoire, d’appareillage sophistiqué ni même d’électricité, peut contribuer à la chaîne diagnostique de la maladie à virus Ebola, en tenant compte de ses avantages, stabilité et spécificité élevées, mais aussi de sa limite de sensibilité par rapport aux techniques moléculaires de laboratoire, qui restent la référence pour le diagnostic de la maladie à virus Ebola. Le TDR Ebola eZYSCREEN® a obtenu le marquage CE-IVD.
Abstract
During the Ebola virus disease outbreak in West Africa in 2014, the World Health Organization has pointed out the need for rapid diagnostic tests (RDT) affordable, sensitive, specific, user-friendly, rapid, equipment-free, and deliverable. The rapid diagnostic test (Lateral Flow Assay) Ebola eZYSCREEN® was developed in this emergency frame using monoclonal antibodies against the envelope glycoprotein of the virus. Two distinct versions have been industrialized, one for whole-blood samples and the other for serum/plasma samples. Both versions have an analytical detection limit of 105 pfu/ml, the stability is at least 393 days at 30°C and 120 days at 45°C. The nonretrospective and independent validation study was carried out in the course of the outbreak in Conakry and at the Ebola Treatment Center of Coyah (Guinea) on 144 patients. In this study, the RDT showed a sensitivity of 65.3% and a specificity of 98.9% on whole blood, a sensitivity of 74.5% and a specificity of 100% on serum. Results from the whole-blood version must be analyzed with caution because of the delay between the blood collection and the completion of the tests, which was out of specification (3 days on average instead of 2 h). In contrast to laboratory tests, this easy to use field test does not require sophisticated instrumentation or even electricity and can contribute to the diagnostic chain of Ebola virus disease taking into account its benefits, high stability, and specificity but also its limit of sensitivity compared to laboratory techniques RT-qPCR (Real-Time reverse transcription Polymerase Chain Reaction), which remain the reference for the diagnosis of Ebola. The RDT Ebola eZYSCREEN® was granted EC IVD (IVD = In Vitro Diagnostic) marking.
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Gallais, F., Gay-Andrieu, F., Picot, V. et al. Validation sur le terrain du nouveau test de diagnostic rapide Ebola eZYSCREEN®. Bull. Soc. Pathol. Exot. 110, 38–48 (2017). https://doi.org/10.1007/s13149-016-0540-z
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DOI: https://doi.org/10.1007/s13149-016-0540-z
Mots clés
- Test de diagnostic rapide
- TDR
- Ebola
- Maladie à virus Ebola
- Épidémie
- Conakry
- Centre de traitement Ebola de Coyah
- Guinée
- Afrique intertropicale