Globalization, climate change, and the re-emergence of West Nile, Dengue, and Zika viruses

Vector-borne viral infections such as West Nile virus (WNV), Dengue virus (DENV), and Zika virus (ZIKV) exemplify how globalization, climate change, and ecological disruption are reshaping the geography of infectious diseases. These flaviviruses, transmitted primarily by Culex and Aedes mosquitoes, have expanded their range beyond traditional tropical and subtropical boundaries, establishing endemic and epidemic cycles in temperate regions. Rising global temperatures, altered rainfall patterns, and urbanization enhance vector breeding, accelerate viral replication, and prolong transmission seasons. Clinically, WNV typically causes asymptomatic or mild febrile illness, though a minority of infections progress to severe neuroinvasive disease, especially in older or immunocompromised individuals. DENV, characterized by four antigenically distinct serotypes, can result in severe DENV due to antibody-dependent enhancement and immune dysregulation. ZIKV infection, often mild or asymptomatic, has revealed serious neurotropic potential, being associated with congenital Zika syndrome and Guillain-Barré syndrome during major outbreaks in the Americas and Pacific Islands. Diagnosis relies on molecular and serological assays, though cross-reactivity between flaviviruses remains a challenge. No specific antiviral therapies are currently available, and prevention depends on integrated vector management, personal protection, and surveillance. Vaccines for DENV are available with serostatus-dependent indications, while those for WNV and ZIKV are under investigation. Understanding the shared ecological and epidemiological determinants of these infections within a One Health framework is crucial to strengthening surveillance, guiding vaccine implementation, and building resilience against future arboviral threats intensified by climate and environmental change.