Use of Dry Blood Spots for Identifying Hepatitis E Infections
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Background
Accurate and accessible diagnostics for hepatitis E virus (HEV) are essential for outbreak preparedness and surveillance, particularly in low-resource settings. Dried blood spots (DBS) offer a simple, scalable alternative to serum, but their diagnostic performance for HEV remains poorly characterised.
Methods
Paired DBS and serum samples were collected from suspected HEV cases during an outbreak in Bentiu, South Sudan. HEV RNA was detected and quantified by real-time RT-PCR, and anti-HEV IgM and IgG antibodies were measured by ELISA. DBS performance was compared to serum across assays, and associations between DBS positivity and serum viral load were analysed using logistic regression.
Results
Among 100 serum RT-PCR positive samples, 83 were positive by DBS (sensitivity 83.0%, 95% CI: 74.5-89.1). Ct values from DBS and serum were strongly correlated (ρ = 0.74), and most discordances at low viral loads (Ct > 30). DBS achieved 88.3% sensitivity (95% CI: 77.8-94.2) and 100% specificity (95% CI: 91.2-100) for IgM, while IgG sensitivity and specificity reached 95.0% (95% CI: 86.3-98.6) and 97.5-100%, respectively. Results were consistent across DBS card types and age groups.
Conclusions
DBS provide a reliable, practical alternative to serum for HEV diagnostics. Despite slightly reduced sensitivity at low viral loads, DBS maintained high specificity and strong correlation with serum results. Their ease of collection, storage, and transport without cold chain requirements supports their application for HEV surveillance and outbreak response in resource-limited settings. Further optimisation of elution methods to increase analyte concentration, along with improved storage conditions, could enhance diagnostic sensitivity.
