PAHO Calls for a Stronger Response to Chikungunya, Oropouche

The Pan American Health Organization (PAHO) calls for reinforced surveillance, clinical management, and vector control to address localized chikungunya outbreaks and the ongoing circulation of the Oropouche virus (OROV) across the Americas. The simultaneous presence of these and other arboviruses increases the risk of outbreaks, severe complications, and fatalities, particularly among vulnerable populations.

According to a PAHO epidemiological alert, the largest chikungunya outbreaks in 2025 have occurred in South America, mainly in Bolivia, Brazil, Paraguay, and parts of the Caribbean. These outbreaks involve both the Asian and East/Central/South African (ECSA) genotypes, marking a shift in patterns observed since 2014. Cases reported in the Indian Ocean region, the European Union, and Asia also raise the possibility of reintroduction into areas with conditions conducive to transmission.

As of Aug. 9, 2025, 14 countries in the region reported 212,029 suspected chikungunya cases and 110 deaths, with over 97% occurring in South America. While this represents a decline compared to 2024, when 431,417 cases and 245 deaths were recorded, localized outbreaks remain active.

Mexico and the Caribbean have registered only a few chikungunya cases so far. However, PAHO warns that seasonal trends indicate potential increases in these regions in the second half of the year, during the rainy season, underscoring the need for continued monitoring and preparedness.

Meanwhile, in the first seven months of 2025, over 12,700 confirmed Oropouche cases were reported in 11 countries, including Brazil, Colombia, Cuba, Panama, Peru, and Venezuela. Historically confined to parts of the Amazon, Oropouche has recently spread to previously unaffected areas, highlighting the importance of strengthened surveillance, including the integration of spatial and temporal analyses and geospatial tools to track vector and case distribution.

Chikungunya is transmitted primarily by the Aedes aegypti mosquito. It causes high fever, rash, and intense muscle and joint pain that can persist for months. Severe cases may progress to shock, meningoencephalitis, or Guillain–Barré syndrome, with young children, older adults, pregnant individuals, and people with underlying health conditions at greatest risk. There is no specific treatment, and prevention relies on avoiding mosquito bites.

Oropouche virus is transmitted mainly by the midge Culicoides paraensis, with the mosquito Culex quinquefasciatus potentially contributing to spread. Symptoms include fever, headache, muscle aches, and sometimes neurological complications. No vaccine or antiviral treatment exists, and care is symptomatic. Up to 60% of patients may experience relapses.