# Reframing West Nile Virus in Latin America: From Enzootic Evidence to Human Risk—Surveillance Gaps and One Health Actions

## TL;DR

West Nile virus is widespread in Latin America but underreported in humans due to weak surveillance and diagnostic systems, requiring improved One Health strategies to prevent outbreaks.

## Contribution

The paper identifies surveillance gaps and proposes One Health actions to address underdiagnosis and preparedness for WNV in Latin America.

## Key findings

- WNV is present in Latin American animals and mosquitoes but human cases are underreported.
- Surveillance gaps and misclassification of febrile illnesses hinder accurate WNV tracking.
- One Health strategies, including diagnostics and predictive models, are needed to strengthen regional preparedness.

## Abstract

West Nile virus (WNV) is a mosquito-borne flavivirus with one of the widest global distributions. Since its discovery in Uganda in 1937, it has become a major zoonotic pathogen, and after its introduction into the United States in 1999, it spread rapidly across the Americas, becoming the leading cause of neuroinvasive arboviral disease. Its expansion illustrates a remarkable ecological adaptability, further intensified by climate change. In Latin America and the Caribbean, WNV circulation has been consistently documented in birds, horses, and mosquitoes; however, confirmed human cases remain disproportionately scarce compared with North America and Europe. Reports include sporadic human cases in Brazil (>100 since 2014), Mexico (~13), Argentina (2006–2007), Puerto Rico (2007), Nicaragua, and Haiti, while animal and vector evidence extends to Guatemala, El Salvador, Belize, Costa Rica, Bolivia, Paraguay, Colombia, Venezuela, Cuba, and Ecuador. This paradox likely reflects structural limitations within regional health systems, including underdiagnosis, restricted diagnostic capacity, and significant surveillance gaps, particularly in contexts where mild febrile syndromes may be misclassified as dengue, Zika, or Chikungunya. The regional risk of emergence is further amplified by climatic variability, ecological change, and intensifying human–wildlife interactions. Experiences from Europe highlight the importance of early detection, transfusion safety, and integrated surveillance within a One Health framework. Strengthening preparedness in Latin America will require investments in diagnostic infrastructure, implementation of standardized seroepidemiological surveys, development of predictive models tailored to local ecological contexts, and robust intersectoral collaboration.