Hepatitis E virus: seroprevalence and frequency of viral RNA detection among US blood donors.

Background: Hepatitis E virus (HEV) is a nonenveloped emerging virus of increasing worldwide interest. Antibody prevalence, RNA frequencies, and transfusion transmissions have been reported. We investigated the HEV RNA and antibody frequencies in US blood donors.
Study Design and Methods: Individual-donation HEV RNA testing was performed on 18,829 donations from six US geographic regions using a CE-marked nucleic acid test (95% limit of detection, 7.9 IU/mL). Repeat-reactive donations were confirmed by in-house, real-time polymerase chain reaction (PCR; 10.3 IU/mL). Total HEV seroprevalence in a randomly selected subset of donations (n = 4499) was assessed by a direct, double-antigen sandwich assay; reactives were further tested for immunoglobulin (Ig)G and IgM. As part of the total antibody confirmatory algorithm, the cutoff was adjusted.
Results: Two donations tested confirmed-positive for RNA (PCR not quantifiable, IgM/IgG positive; and 14 IU/mL, antibody negative) for a frequency of 1 in 9500 (95% confidence interval [CI], 1:2850-1:56,180) and 99.96% specificity (95% CI, 99.92%-99.98%); both donors were from the Midwest United States. Antibody prevalence was 9.5% (95% CI, 8.7-10.5) before the cutoff adjustment and 7.7% (95% CI, 7.0%-8.5%) after adjustment; 0.58% (95% CI, 0.39%-0.85%) were IgM positive.
Conclusions: We confirmed comparatively low rates and low viral loads of HEV RNA in US blood donors indicating the need for individual-donation testing if screening is implemented. Antibody prevalence rates were comparable to those reported by one US study using a different assay, but lower than those reported in another study using yet a third assay. We did not answer the question of whether US blood donation screening is warranted. Selective strategies involving providing HEV-negative blood to severely immunosuppressed patients at risk of developing hepatitis may be considered.
(© 2015 AABB.)