Researchers screening blood donors in Argentina during a mosquito-borne virus outbreak found the virus in someone who felt completely fine. Among 637 donors living in outbreak-affected areas, one carried the Western equine encephalitis virus in their blood without any symptoms.
The finding was published in Emerging Infectious Diseases, the CDC's peer-reviewed journal. Genetic sequencing placed the donor's virus within the contemporary South American outbreak lineage, consistent with ongoing regional transmission rather than an unrelated source.
