Dengue and Zika viruses circulate in Mexico and cause annual outbreaks with varying severity, indicating ongoing selection for different virus variants.
Researchers studied blood samples from patients in Oaxaca during 2016 and 2019 to see if different virus variants were present during outbreaks.
They found that the ability of the viruses to withstand type I interferon antiviral responses and the accumulation of certain RNA in infected cells are linked to disease severity and certain blood conditions.