Summary
Oropouche virus (OROV) spread rapidly across the Americas in 2024, yet Panama's Darién migration corridor recorded no recognised outbreak until nearly a year after Brazil's January 2024 peak. This delay raised two competing hypotheses: prolonged cryptic circulation masked by diagnostic gaps or a recent viral introduction coinciding with permissive climatic conditions.
Using integrated clinical, genomic, and climate-informed surveillance across 1,040 tested individuals, this study resolves the Darién paradox:
High Burden & Distinct Clinical Signature: 43% of patients tested OROV-positive, exhibiting a clinical profile distinct from co-circulating arboviruses—including headache occurring at more than double the frequency observed in dengue (RR 2.38, 95% CI 1.74–3.24).
Intense Household Transmission: The household secondary attack rate reached 56%, and peridomestic waste burning independently predicted infection.
Single Recent Introduction: Phylogeographic reconstruction identified a single introduction in October 2024 with no evidence of adaptive evolution, ruling out prolonged cryptic persistence.
Regional Vulnerability: Climate-informed models indicate broad outbreak susceptibility across Panama—highlighting Bocas del Toro and Los Santos as the next highest-risk provinces—and identify a Central American foothold for OROV with potential for further northward spread.
