19 Nov New Test Suggests Hepatitis E May Be Widely Underestimated
MedicalResearch.com Interview with:
Brittany Kmush, ScM
Doctoral Candidate
Global Disease Epidemiology and Control
Department of International Health
Johns Hopkins Bloomberg School of Public Health
Baltimore, MD
Medical Research: What is the background for this study? What are the main findings?
Response: Hepatitis E virus (HEV) is a global pathogen responsible for approximately 20 million infections every year in developing countries. In the general population, HEV causes acute, self-limiting hepatitis with only a 1-2% case fatality rate. However, in pregnant women, Hepatitis E virus infection can be very severe, resulting in fulminant hepatic failure and death, with a case fatality rate around 30%. Despite this important burden, Hepatitis E virus remains an under-recognized and under-reported pathogen. The early years of HEV research were plagued by poor quality commercial assays, highly variable in sensitivity and specificity. As a result, there is still no diagnostic assay approved for commercial use in the United States. However, over the past two decades, several new, highly sensitive and specific assays have been developed.
In this study, we re-tested banked sera from a population-based sero-survey of over 1000 participants from rural Bangladesh in order to investigate the comparability of a high-performing first generation test to recently developed, commercially available assay. In the early 2000s, the Walter Reed Army Institute of Research (WRAIR, Bethesda, MD) developed an in-house enzyme immune-assay (EIA) to diagnose Hepatitis E virus infections by detecting anti-HEV total immunoglobulin (Ig) in serum. More recently, Wantai Diagnostics (Beijing, China) developed a commercially available EIA for detecting anti-HEV IgG.
The WRAIR assay estimated the overall population seroprevalence as 26.6% while the Wantai assay produced significantly higher estimated seroprevalence, 46.7%. There was a 77% agreement between the two tests. Overall, the Wantai assay found a much higher seroprevalence of anti-HEV antibodies compared to the WRAIR assay, using the same serum. Additionally, the majority of the differences between the two tests are from people initially classified by WRAIR as anti-HEV negative that Wantai classified as anti-HEV positive.
Medical Research: What should clinicians and patients take away from your report?
Response: This study exposes the possible widespread underestimation of population seroprevalence for anti-HEV antibodies over the past two decades, even in rigorous studies which used widely accepted “gold standards” such as the WRAIR assay. It is likely that many population studies have significantly underestimated the burden of this disease, in both developing and developed countries. Global burden estimates developed by Rein et al in 2012, relied heavily on studies which used the WRAIR assay, potentially underestimating the global importance of this pathogen.
Medical Research: What recommendations do you have for future research as a result of this study?
Response: It is imperative to re-test populations with modern assays to establish better population-level estimates of disease burden, as well as establish serologic standards to improve the quality and comparability of anti-HEV results across assays.
Citation:
Am J Trop Med Hyg. 2015 Oct 7;93(4):714-7. doi: 10.4269/ajtmh.15-0159. Epub 2015 Jul 6.
Kmush BL1, Labrique AB2, Dalton HR1, Ahmed ZB1, Ticehurst JR1, Heaney CD1, Nelson KE1, Zaman K1.
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Brittany Kmush, ScM (2015). New Test Suggests Hepatitis E May Be Widely Underestimated MedicalResearch.com
Last Updated on November 19, 2015 by Marie Benz MD FAAD