Decryption of Oropouche virus | Doherty website

In 2023, major OROV outbreaks occurred in South America. As of mid-October 2024, the Pan American Health Organization (PAHO) reported over 10,000 confirmed cases across the Americas and Europe, with the majority recorded in South America, including more than 8,000 infections in Brazil. Cases linked to travel from regions with ongoing outbreaks have also been identified in the United States, Canada and Europe.

Royal Melbourne Hospital's Chuan Lim Kok, medical virologist and acting director of the Victorian Infectious Diseases Reference Laboratory (VIDRL) ​​at the Doherty Institute, explains key facts about the virus.

OROV is a recurrent arbovirus, meaning it spreads to people and animals through the bites of infected mosquitoes, ticks, and midges, particularly midges Culicoides paraensis Species. Although the virus is rarely fatal, it can cause significant discomfort.

In non-urban environments, OROV is transmitted between mosquitoes and animals such as sloths, monkeys and birds. Although the virus has been found in semen, there are currently no reports of direct human-to-human transmission.

The virus is most common in Central and South America and can cause large outbreaks, particularly in urban areas.

Symptoms of an OROV infection typically appear within three to ten days of exposure. Common signs include fever, headache, or muscle pain (myalgia), many of which are similar to symptoms of dengue or chikungunya virus infections.

Occasionally, infected people may experience pain behind the eyes (retroorbital pain) or a red rash with flat and raised parts (maculopapular rash) that originates centrally in the body and spreads to the limbs.

Most symptoms are usually short-lived and usually resolve within a week, but sometimes they may recur after a few days to a few weeks.

In rare cases, serious complications such as meningitis, encephalitis and Guillain-Barré syndrome, a condition in which the immune system mistakenly attacks the peripheral nerves, have been reported, and in some cases there have been deaths. Pregnancy complications such as fetal death and congenital disorders related to mother-to-child transmission are also examined.

There is currently no antiviral treatment for OROV. Treatment is primarily about relieving symptoms.

The primary vector of OROV, the Culicoides paraensis Mosquitoes are primarily found in the Americas, reducing the likelihood of significant outbreaks in regions such as Australia. However, health authorities remain vigilant as environmental changes and global travel could affect the spread of the virus.

Australians traveling to South America are advised to use bite prevention methods, including insect repellent and protective clothing.

Although reported cases of OROV in South America declined at the end of 2024, future outbreaks are expected given the widespread presence of OROV Culicoides paraensis There are concerns in both North and South America about the possible spread of the virus to new regions.