Molecular confirmation of transfusion-transmitted dengue virus infection following platelet transfusion in the Chinese mainland

Background Dengue virus (DENV) is considered an emerging threat to blood safety. While transfusion-transmitted DENV (TT-DENV) cases have been documented, TT-DENV has never been reported in Chinese mainland. In this study, a retrospective investigation was conducted after two patients developed dengue fever (DF) following apheresis platelet (PLT) transfusion from the same healthy donor. Methods Blood samples from the recipients and the donor were tested for DENV RNA by nucleic acid testing (NAT). Nonstructural protein 1 (NS1) antigen and anti-DENV immunoglobulin M/G (IgM/IgG) antibodies were detected by ELISA. To confirm transmission, DENV E gene fragments were amplified, and whole-genome sequences were obtained by metagenomic next-generation sequencing (mNGS). Results Our results revealed that the PLT donor was asymptomatic, tested positive for DENV RNA, and negative for anti-DENV IgM/IgG antibodies at donation. After donation, no dengue-like symptoms was developed. Seroconversion was observed at day 21 postdonation. After receiving the DENV-positive PLT unit, recipient 1 had DF only, while recipient 2 developed DF together with headache, joint/muscle pain, and rash. After transfusion, both recipients were positive for DENV RNA and NS1 while negative for anti-DENV IgM/IgG antibodies. Viral sequences from the donor and recipients were identical and belonged to DENV-2. Conclusions To our knowledge, this is the first TT-DENV case reported in the Chinese mainland, revealing the necessity of revising current donor deferral policies and testing strategies that predominantly rely on symptoms and travel history.