Oropouche Outbreaks in the Americas at Infection Point

For unknown reasons, the Region of the Americas has been experiencing an Oropouche virus (OROV) outbreak of unprecedented magnitude since 2023.

As of April 2025, ORIV outbreaks have been identified in ten countries in the Americas, with visitors from those countries bringing the virus into the United States.

According to an open-access article published by The Lancet Infectious Diseases on April 14, 2025, data suggest that climatic factors are major drivers of OROV spread and may have been potentially exacerbated by recent weather events.

These researchers wrote, "While other studies on the 2023–24 OROV outbreak have typically focused on analyzing country-level geographical spread, individual socioecological predictors of OROV infection, or viral genomes..." Our analyses rely on an unprecedented serological OROV dataset comprising over 9,000 samples from six countries and multiple ecozones.

We show that OROV is a common arboviral infection in the South American Amazon.

Specifically, OROV and OROV reassortants, but not individual OROV strains, might represent distinct serotypes.

A strain from the 2023–24 OROV outbreak (IRCCS-SCDC_1/2024) did not stand out from either a historical or another contemporary strain in terms of its replication capacity or antigenicity.

Our evidence indicates that OROV infections are significantly underreported in the Americas.

As climate predictors were the most critical predictors in our OROV transmission risk models, the risk of OROV infection is likely to evolve dynamically in the coming decades, with the potential for large-scale future outbreaks. 

These researchers suggest preparedness for OROV outbreaks requires enhanced diagnostics, surveillance, and vector control in current and future endemic areas, which could all be informed by the risk predictions presented in this Article.

To alert international travelers of the OROV health risk, the U.S. CDC has issued Level 1 and Level 2 Travel Health Advisories in 2025, which identify outbreaks in various countries.

As of April 19, 2025, no OROV vaccines are available, meaning the best defense against OROV infections is to prevent mosquito bites.