The silent invaders: Oropouche and Melao viruses, causes of increased public health risks for the Americas.

The Oropouche virus (OROV) is emerging as a major public health threat worldwide, yet for the Americas, it raises complex challenges that intersect with other existing arboviral threats such as Zika (ZIKV), dengue (DENV) and Chikungunya (CHIKV) viruses. Originating from Trinidad and Tobago in 1955, it has spread across the Amazonian Basin and more recently into the Caribbean (Cuba and Haiti) and Europe, highlighting the importance of air travel in its dissemination. OROV and the less studied Melao virus (MELV), pose significant laboratory diagnostic challenges particularly in regions co-endemic with other arboviral diseases, such as dengue and Zika fever. The effects of climate change, particularly in the Caribbean, may exacerbate the transmission of these viruses by exposing human exposure risk to vectors. Public health systems in the Americas are under strain due to complex clinical management of these infections necessitating enhanced surveillance, clinical vigilance, diagnostics and vector control. Vulnerable populations, including pregnant women, elderly, and young children, are at a heightened risk, which raises concerns about the impact on medical tourism in the region. To mitigate the spread and impact of OROV and MELV, recommendations include increased clinical surveillance, improved laboratory diagnostics, public health communication, and strengthened vector controls. Robust research and capacity building (including training and education) efforts are essential to address knowledge gaps and effectively manage future OROV and MELV outbreaks in the Americas.