Oropouche fever is a viral and little-known disease.

BY AFP

Two people have died in Brazil from Oropouche fever, the first deaths in the world from the disease, which is caused by a little-known virus spread through the bites of infected mosquitoes and gnats.

Here’s what we know so far about this arbovirus, a type of virus transmitted to humans by certain insects.

Two women from the state of Bahia in northeastern Brazil, “under 30 years of age, without underlying medical conditions” but with “symptoms similar to severe dengue,” have died from Oropouche fever, according to Brazil’s Health Ministry.

“So far, no deaths related to this disease have been reported in the world scientific literature,” Brazilian authorities said, also citing an investigation into another death possibly related to the fever in the south of the country.

First discovered in the Trinidad and Tobago archipelago in 1955, this arbovirus is primarily transmitted to humans through mosquito bites, but can also be spread by mosquitoes.

“According to our current knowledge, the virus is not transmitted directly from person to person,” Italian infectious disease specialist Concetta Castiglietti told AFP.

Brazilian health authorities are also investigating six possible cases of transmission of the disease from pregnant women to their children.

Until now, Oropouche fever has been detected mainly in areas of South America, Central America and the Caribbean.

According to the Pan American Health Organization (PAHO), affiliated with the World Health Organization (WHO), more than 7,700 cases have been reported in five countries since the beginning of 2024: Brazil, Bolivia, Peru, Cuba and Colombia. Brazil alone has recorded 7,236 cases to date.

The first deaths announced by Brazil coincide with a serious dengue epidemic that has already killed thousands of people.

Earlier this year, two cases of Oropouche fever were identified for the first time in Europe in two unrelated people who returned to Italy after a trip to Cuba, Concetta Castiglietti said.

The virus causes symptoms similar to dengue fever: fever, muscle pain, joint stiffness, headache, vomiting, nausea, chills, or sensitivity to light.

Severe forms can lead to life-threatening complications such as meningitis.

There are no specific treatments or vaccines.

In affected areas, the best protection is to avoid mosquito and gnat bites, cover your legs and arms, and use repellents and fine-mesh mosquito nets, according to PAHO.

Compared to other arboviruses in this family, such as dengue and chikungunya, Oropouche fever has not been extensively studied, and many unknowns remain, including the exact number of confirmed cases.

In addition, it is difficult to distinguish from dengue fever, and, among other things, the transmission cycle between animals and humans or complicating factors are unknown.

According to an article published in the journal Lancet Infectious Diseases, it is a classic example of a “forgotten” disease.

The authors of the paper believe that the virus “has the potential to become a serious threat” given its presence in different environments, the number of species that can transmit it, and the risk of serious complications.

According to Concetta Castiglietti, regional, national and international authorities need to communicate more and prepare for possible epidemics.

“We must expect the unexpected, which is what the Covid-19 pandemic should have taught us,” says an Italian scientist.

In recent years, experts have also warned about the effects of global warming, which is increasing the presence of mosquitoes in many parts of the world and thus increasing the risk of spreading diseases such as dengue and Oropouche fever.