What we know so far about Oropouche virus after first deaths

The first-ever deaths from the Oropouche virus, a little-known disease spread by the bites of infected midges and mosquitoes, have been recorded in Brazil. 

Two women under 30 years old from the Brazilian state of Bahia have become the first known people to have died from the virus, Brazil's health ministry said.

They showed symptoms similar to dengue, another mosquito-borne virus which is often confused with Oropouche.

Here's what we know about the virus so far.

What is it?

The virus was first detected in Trinidad and Tobago in 1955.

It is transmitted mostly through the bites of midges, though it can also be spread via mosquitoes.

"It's very important to point out that, according to our current knowledge, the virus is not transmitted directly from human to human," Italian infectious disease researcher Concetta Castilletti told AFP. 

This means that travellers visiting affected regions cannot transmit the virus elsewhere.

Authorities in Brazil are investigating recent reports that pregnant women could have transmitted the virus to their unborn children, according to the Pan American Health Organization (PAHO).

Where is it?

The virus has been reported in parts of South America, Central America and the Caribbean.

PAHO said that more than 7,700 cases of Oropouche virus have been detected so far this year in five countries: Brazil, Bolivia, Peru, Cuba and Colombia.

Brazil alone has recorded 7,236 cases in 2024, according to its health ministry.

What are the symptoms?

The virus causes similar symptoms to dengue, such as fever, muscle aches, stiff joints, headache, vomiting, nausea, chills or sensitivity to light, according to the US Centers for Disease Control and Prevention. 

Severe cases can result in life-threatening complications such as meningitis.

There are no specific treatments or vaccines for the virus.

The best protection is to avoid getting bitten by midges and mosquitoes when in an affected area.

That includes covering up legs and arms, using strong bug repellent and fine-mesh mosquito nets, since midges can get through traditional nets, according to PAHO.

Threat of a wider outbreak?

Compared to other viruses in its family, such as dengue and chikungunya, the virus is considered understudied and little understood.

A Lancet review earlier this year called the virus "a prototypical neglected disease."

The review added that the virus "has the potential to emerge as a substantial threat" given its potential to spread widely and cause serious health problems.

Castilletti's laboratory detected the first two cases ever recorded in Europe, in two unrelated passengers who returned to Italy from a trip to Cuba earlier this year.

Because of the high numbers of travellers visiting the affected regions, "we can reasonably expect more cases" in Europe, she said.

Researchers have been sounding the alarm that warmer temperatures driven by climate change have been increasing the range of mosquitoes across the world. This in turn could raise the potential spread of viruses such as Oropouch, Castilletti said. 

What needs to be done?

She said that researchers need to study the virus more to understand how it affects different kinds of people. 

A test that can rapidly detect the virus at the "earliest possible stage" is also needed, Castilletti said.

She also called for regional, national and international health authorities to ramp up communication and preparedness to prevent potential outbreaks in the future.

"'Expect the unexpected,' as the COVID-19 epidemic should have taught us," she added. (AFP)