Silent St. Louis encephalitis virus circulation evidence by a haemovigilance survey in a centralized blood bank

Saint Louis encephalitis virus (SLEV) re-emergence and its geographical expansion, evidenced by its emergence in previously unaffected areas, have raised significant public health concerns. We aimed to show the usefulness of haemovigilance as an effective tool to fill arboviruses surveillance gaps to track trends and identify hotspots.

Within the framework of a blood bank haemovigilance program, we performed a survey to evaluate the potential threat of circulating mosquito-borne infections for transfusion safety. SLEV was detected by a PCR targeting the conserved NS5-gene region, and the PCR-product was subjected to direct nucleotide sequencing reaction.

The SLEV-strain detected in the blood donor (OR236721) clustered with previously reported CbaAr-4005, 79 V-2533, and MN413675 isolated in Córdoba (2005, epidemic), Santa Fe (1979, non-epidemic) and Buenos Aires (2013, non-epidemic), with 97% identity.

Herein, we show the usefulness of haemovigilance in uncovering the silent circulation of arboviral infections. Implementing this systematic surveillance approach would allow for monitoring the distribution and incidence of vector-borne diseases, providing information that could prevent the spread of the virus and its introduction into novel biomes. Ultimately, leveraging haemovigilance enables timely identification of potential outbreaks and empowers policymakers to make well-informed decisions to safeguard public health.