The study contains new risks from viral redesign

A new study shows how Oropouche virus breaks out of the Amazon and spreads into Brazil and beyond. Scientists warn that environmental changes, human mobility and viral evolution promote their rapid expansion – and urgent concerns about global public health.

Study: travel-related international spread of the Oropouche virus beyond the Amazon. Photo credits: CI photos / Shutterstock

The Oropouche Virus (OOV), which is historically limited to the Brazilian Amazon Basin, has caused several outbreaks in many Brazilian states since 2022. Many orov cases have recently been discovered beyond Brazil.

Researchers have carried out the sequencing of virusisolates in the entire genome from outbreak regions in order to understand the dynamics of virus transmission to non -endemic regions. The study is published in the Journal of Travel Medicine.

background

The Oropouche virus (OOV) is a drunken RNA virus transmitted by arthropods, which is segmented in three parts: small, medium and large. These three segments encode essential components that are required for virus growth, transmission and infectiousity.

After The first detection in Trinidad and Tobago in 1955 caused the virus in the Amazon basin several outbreaks in animals (non-human primates, sloths and birds). In humans, the virus is mainly transmitted by mosquitoes (by mosquitoes (Culicoides paraenesis) and causes light to moderate infections that dissolve within a week.

By August 2024, around 30 outbreaks were reported in Latin America. However, the latest epidemiological data show a strong increase in the Orov cases in several non-endemic Brazilian countries, whereby in Italy, Spain and Germany, traveling devices from travelers who visited Cuba were reported.

The first three fatal cases of Ovov infections were also reported in Brazil in 2024. All of these reports underline the spread of the virus outside the Amazon and make concerns about the authorities of public healthcare.

Study design

The researchers carried out the sequencing of the entire genome of rehearsals derived from Orov, which were collected from five Brazilian countries between February and May 2024. They chose the samples for the genomic analysis based on the available clinical and epidemiological metadata.

They produced 133 sequences of the entire genome that cover the three genomic segments of the virus: the small, medium -sized and large segments. These sequences included the first genomes from regions outside the Amazon and from the first listed cases.

Study results

The study reported on a strong increase in Orov infections in humans in the western Amazon region between the end of 2022 and early 2024. This induction coincided with an increase in the Orov test frequency (from 238 tests in 2020 to 54,428 in early 2024), which indicates intensified surveillance efforts.

The phylogenetic analysis showed that the new virus sequences generated in the study have a common ancestor with sequences that have been received from the Amazon basin since 2022, which indicates a possible Amazona jump of the latest viral line.

Due to its segmented pattern, the Orov genome is probably subjected to a new edition and recombination events. The study identified 21 reform events (including 17 SM, 7 SL and 11 ml reforms). It remained unclear whether these genomic changes made the viral adaptation to local ecological diseases or contributed to their infectiousity and pathogenicity.

By carrying out a phylogeographic reconstruction of the Brazilian data set 2022-2024 together with recently isolated international genome sequences from Peru and Italy, the study found a quick north-after-south virus transmission within Brazil, followed by cross-border transmission in Peru.

The study also showed that Orov cases reported in Italy are connected to travelers who have returned from Cuba. However, Cuban cases are derived exclusively from the history of travel, since genomic data from Cuba itself are not available and final conclusions are limited to transmission routes. These observations underline the role of human mobility in virus spread.

Examine significance

The study shows how the Orov Evolution has made it easier to transmit its quick transmission within and outside of Brazil through genomic reforms. The results show that between 2010 and 2014 the line from 2022–2024 was created in the central Amazon in Central AMAZONA, with a long-term cryptic cycle in the Amazon in the late 2010s due to limited surveillance.

The north to the south virus movement of the study coincides with the rainy season of the Amazon basin. Existing eco-epidemiological studies suggest that Orov preferably circulates in regions with high population density, favorable climatic conditions and reduced evergreen wide forest cover.

In addition, deforestation, urbanization and agricultural practices (e.g. banana and cocoa cultivation) make the Midge breeding, which increases the risk of virus transmission and the geographical area of ​​the virus is designed.
The proof of the first three fatal orov cases in young adults without comorbidities – including mutations in the segments M (I13V, M642i) and L (T857A) – underlines the need for further studies with a special focus on vertical transmission and pregnancy results.

The Brazilian Ministry of Health recently reported the first fetal death due to Orov with mother-child transmission in Pernambuco. However, asymptomatic or mild cases can be underrepresented in genomic data records, which has contained the monitoring effort. This underlines the need to identify viral factors that are associated with serious results and develop effective interventions.

In the study, Orrov-related cases were identified in connection with travel, which indicates that human mobility plays an important role in spreading virus over Brazil. The most important restrictions include the lack of genomic data from Colombia, Cuba and other affected countries that prevent a complete understanding of the transmission networks.

Overall, the study underlines urgency for continuous genomic monitoring, to understand the evolutionary and epidemiological dynamics of OOV. This is particularly important to prevent future outbreaks and to ensure timely reactions to public health.