Environmental factors, such changing temperatures and rainfall, are the main drivers associated with the spread of Oropouche virus (OROV) in Latin America, according to a modelling study published in The Lancet Infectious Diseases journal and presented at the ESCMID conference.
The study also suggests that OROV infections in Latin America may be underestimated, with the assessment of over 9,000 human samples collected between 2001 and 2022 for OROV antibodies finding that 6.3% of samples were positive for OROV.
OROV is a virus endemic to Latin America. The region has been experiencing an OROV outbreak of unprecedented magnitude since 2023, with the virus spreading to densely populated areas outside of the Amazon basin (where OROV was mostly detected previously). Recent research has considered various potential drivers of this recent outbreak, including the presence of a more transmissible strain of OROV, and more vigilant OROV testing leading to a detection of more cases, however, substantial uncertainty remained due to a lack of comprehensive data.
The current study aimed to characterise the prevalence of OROV and factors underlying its spread across Latin America, by combining the analysis of human samples from Bolivia, Brazil, Colombia, Costa Rica, Ecuador, with computer modelling. The model found a clear correlation between environmental factors and OROV spread, with these factors accounting for the majority (over 60%) of the variation.
The model identified other contributing factors to OROV spread, including distance to human settlements (10%) and deforestation (4.5%). The study also underscored that extreme weather events, including El Niño, may have exacerbated the recent outbreak, and that future land-use changes such as deforestation could further contribute to outbreaks.
The authors say that as their model indicates that environmental factors are strongly associated with OROV spread in Latin America, OROV infection risk will likely change in the coming decades alongside changing weather and temperatures, with the potential for future large-scale outbreaks. They highlight the need for improved OROV surveillance and diagnostic testing strategies, clinical practices, and research into new vaccine candidates to mitigate future outbreaks.
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(25)00110-0/fulltext
