Blood transfusion safety depends on knowing which pathogens circulate silently in donor populations — and emerging arboviruses increasingly complicate that picture. A cross-sectional Iranian study offers a useful regional snapshot of two mosquito-borne viruses that have expanded their geographic footprints considerably over the past decade, with findings that are cautiously reassuring yet underscore the need for continued vigilance.
Among 314 asymptomatic blood donors screened between late 2023 and mid-2024 in Fars province, southwestern Iran, neither West Nile virus (WNV) nor Chikungunya virus (CHIKV) RNA was detected by RT-PCR targeting the WNV polyprotein and CHIKV E1 envelope genes. Applying the rule-of-three statistical correction to these zero-event results places the upper 95% confidence bound for active viremia at under 1% per pathogen — a practically meaningful ceiling. Serology told a different story for WNV: 12 donors (3.82%) carried IgG antibodies indicating prior exposure, with slightly higher prevalence around Shiraz (4.3%) than Jahrom (2.9%). Notably, 91.7% of seropositive individuals were male and 83.3% reported outdoor occupational exposure such as farming or manual labor — an epidemiological profile consistent with vector-contact risk. No CHIKV seropositivity or IgM reactivity was detected for either virus.
This research sits within a growing body of evidence documenting WNV's quiet but persistent presence across the Middle East and Central Asia, where seroprevalence surveys regularly identify past exposure in populations that never received clinical diagnoses. The absence of CHIKV antibodies is notable given recent outbreaks in neighboring regions, though the sample size limits sensitivity to rare events. A key methodological limitation is the absence of plaque-reduction neutralization testing, which means ELISA IgG positivity could include cross-reactive antibodies from related flaviviruses. The cohort is also restricted to voluntary blood donors — likely healthier and more urban than the general population — potentially underestimating true community exposure. Overall, this is an incremental but geographically valuable contribution: active transfusion-transmitted risk appears low currently, yet the documented seroprevalence warrants ongoing arboviral surveillance in blood banking systems across the region.