Field Validation of the ReEBOV Antigen Rapid Test for Point-of-Care Diagnosis of Ebola Virus Infection.

BACKGROUND: The 2013-2016 West African Ebola virus disease (EVD) epidemic is the largest recorded. Triage on the basis of clinical signs had limited success, and the time to diagnosis by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) could exceed 5 days. Here we describe the development and field validation of the ReEBOV Antigen Rapid Test (ReEBOV RDT) to aid triage of individuals with suspected EVD. METHODS: Samples from patients with suspected EVD were submitted to Kenema Government Hospital, Sierra Leone, for Lassa fever and EVD screening throughout 2014. Banked residual clinical samples were tested in November 2014 and January 2015 in a blinded field trial to estimate the clinical effectiveness of the ReEBOV RDT, compared with EBOV-specific qRT-PCR. RESULTS: Preliminary ReEBOV RDT performance demonstrated a positive percentage agreement (PPA) of 91.1% (195 of 214 results; 95% confidence interval [CI], 86.5%-94.6%) and a negative percentage agreement (NPA) of 90.2% (175 of 194; 95% CI, 85.1%-94.0%). The final estimates used by the Food and Drug Administration to determine whether to grant emergency use authorization for the test, which excluded a qRT-PCR reference method threshold cutoff, were a PPA of 62.1% (72 of 116 results; 95% CI, 52.6%-70.9%) and a NPA of 96.7% (58 of 60; 95% CI, 88.5%-99.6%), with a diagnostic likelihood of 18.6. A subsequent, independent evaluation by the World Health Organization generated results consistent with the preliminary performance estimates. CONCLUSIONS: The ReEBOV RDT demonstrated the potential to provide clinically effective rapid and accurate point-of-care test results and, thus, to be a powerful tool for increasing triage efficiency.

Undiagnosed acute viral febrile illnesses, Sierra Leone.

Sierra Leone in West Africa is in a Lassa fever-hyperendemic region that also includes Guinea and Liberia. Each year, suspected Lassa fever cases result in submission of ≈500-700 samples to the Kenema Government Hospital Lassa Diagnostic Laboratory in eastern Sierra Leone. Generally only 30%-40% of samples tested are positive for Lassa virus (LASV) antigen and/or LASV-specific IgM; thus, 60%-70% of these patients have acute diseases of unknown origin. To investigate what other arthropod-borne and hemorrhagic fever viral diseases might cause serious illness in this region and mimic Lassa fever, we tested patient serum samples that were negative for malaria parasites and LASV. Using IgM-capture ELISAs, we evaluated samples for antibodies to arthropod-borne and other hemorrhagic fever viruses. Approximately 25% of LASV-negative patients had IgM to dengue, West Nile, yellow fever, Rift Valley fever, chikungunya, Ebola, and Marburg viruses but not to Crimean-Congo hemorrhagic fever virus.

The voluntary HIV counselling and testing service in Kenema District, Sierra Leone, 2004-2006: a descriptive study.

BACKGROUND: Voluntary counselling and testing (VCT) is an important component of national HIV programs, which are necessary to realize the right to health. VCT data also provide valuable information on regional HIV epidemiology. METHODS: The study examines data on the population that obtained HIV VCT in Kenema District, Sierra Leone, from 2004 to 2006, using descriptive statistics and exploring potential HIV risk factors using bivariate and multivariable logistic regression. Analysis was performed separately for two subpopulations: those accessing VCT routinely as part of antenatal care and those specifically seeking VCT. RESULTS: During this period, 2230 people accessed VCT: 1213 through antenatal testing and 1017 specifically seeking VCT. The HIV prevalence was 0.6% in women presenting for antenatal care, 12.6% in women specifically accessing VCT, and 6.7% in men specifically accessing VCT. In both bivariate and multivariable analyses, being female was statistically significantly associated with testing positive in people specifically seeking VCT. CONCLUSIONS: These data from the VCT service in Kenema will be used to improve the accessibility of HIV testing. Questions raised by the analysis will be used to enhance data collection and to inform further research on risk factors.