Evaluation of a point-of-care blood test for identification of Ebola virus disease at Ebola holding units, Western Area, Sierra Leone, January to February 2015

N F Walker; C S Brown; D Youkee; P Baker; N Williams; A Kalawa; K Russell; A F Samba; N Bentley; F Koroma; M B King; B E Parker; M Thompson; T Boyles; B Healey; B Kargbo; D Bash-Taqi; A J Simpson; A Kamara; T B Kamara; M Lado; O Johnson; T Brooks

doi:10.2807/1560-7917.ES2015.20.12.21073

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Evaluation of a point-of-care blood test for identification of Ebola virus disease at Ebola holding units, Western Area, Sierra Leone, January to February 2015
N F Walker^1,2,3 , C S Brown^1,4 , D Youkee¹ , P Baker¹ , N Williams⁵ , A Kalawa⁵ , K Russell⁶ , A F Samba⁷ , N Bentley⁶ , F Koroma⁷ , M B King⁷ , B E Parker⁷ , M Thompson⁷ , T Boyles^1,8 , B Healey¹ , B Kargbo⁷ , D Bash-Taqi⁷ , A J Simpson⁶ , A Kamara⁷ , T B Kamara⁷ , M Lado¹ , O Johnson¹ , T Brooks⁶
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Affiliations: ¹ King’s Sierra Leone Partnership, King's Centre for Global Health, King's College London, and King’s Health Partners, London, United Kingdom ² Department of Infectious Diseases and Immunity, Imperial College London, London, United Kingdom ³ Clinical Infectious Diseases Research Initiative, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa ⁴ Hospital for Tropical Diseases, University College London Hospital, London, United Kingdom ⁵ College of Medicine and Allied Health Sciences, Freetown, Sierra Leone ⁶ Rare and Imported Pathogens Laboratory, Public Health England, Salisbury, United Kingdom ⁷ Ministry of Health and Sanitation, Sierra Leone ⁸ Division of Infectious Diseases and HIV Medicine, Department of Medicine, University of Cape Town, Cape Town, South Africa

Correspondence:
T Brooks
Tim.Brooks phe.gov.uk
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Citation style for this article: Walker N F, Brown C S, Youkee D, Baker P, Williams N, Kalawa A, Russell K, Samba A F, Bentley N, Koroma F, King M B, Parker B E, Thompson M, Boyles T, Healey B, Kargbo B, Bash-Taqi D, Simpson A J, Kamara A, Kamara T B, Lado M, Johnson O, Brooks T. Evaluation of a point-of-care blood test for identification of Ebola virus disease at Ebola holding units, Western Area, Sierra Leone, January to February 2015. Euro Surveill. 2015;20(12):pii=21073. https://doi.org/10.2807/1560-7917.ES2015.20.12.21073 Received: 16 Mar 2015

Abstract

Current Ebola virus disease (EVD) diagnosis relies on reverse transcription-PCR (RT-PCR) technology, requiring skilled laboratory personnel and technical infrastructure. Lack of laboratory diagnostic capacity has led to diagnostic delays in the current West African EVD outbreak of 2014 and 2015, compromising outbreak control. We evaluated the diagnostic accuracy of the EVD bedside rapid diagnostic antigen test (RDT) developed by the United Kingdom's Defence Science and Technology Laboratory, compared with Ebola virus RT-PCR, in an operational setting for EVD diagnosis of suspected cases admitted to Ebola holding units in the Western Area of Sierra Leone. From 22 January to 16 February 2015, 138 participants were enrolled. EVD prevalence was 11.5%. All EVD cases were identified by a positive RDT with a test line score of 6 or more, giving a sensitivity of 100% (95% confidence interval (CI): 78.2-100). The corresponding specificity was high (96.6%, 95% CI: 91.3-99.1). The positive and negative predictive values for the population prevalence were 79.0% (95% CI: 54.4-93.8) and 100% (95% CI: 96.7-100), respectively. These results, if confirmed in a larger study, suggest that this RDT could be used as a 'rule-out' screening test for EVD to improve rapid case identification and resource allocation. .