Carnival party-goers told to cover up as mosquito-borne virus surges in Rio de Janeiro

Party-goers at Rio de Janeiro’s world-famous Carnival have been urged to cover their bodies to protect against mosquito bites following a surge in dengue fever cases across Brazil.

The city declared a public health emergency earlier this week after 364,855 infections of the mosquito-borne virus were reported nationwide last month – more than four times the average rate for January.

Ten treatment centres have been opened to ease pressure on Rio’s overwhelmed hospitals, with fumigators also set to be deployed in high-incidence areas to diffuse the air with insecticide.

As millions descend on Rio for the city’s iconic open-air Carnival, which begins on Friday, Dr Katherine O’Reilly, Regional Medical Director at International SOS, a health risk analysis company, urged those planning to attend the celebrations to consider how they dress.

“Wear clothes that cover your body: long sleeves, long pants – I know that goes against the general Carnival dress code,” she said.

“The most important thing is bite prevention. If you don’t get bitten, you don’t get dengue.” 

Known as ‘breakbone fever’ – because it can cause severe joint pain – dengue is spread by the Aedes aegypti mosquito. Other symptoms include a high fever, headache, vomiting, and an itchy skin rash. In rare cases, the disease can cause severe bleeding, resulting in death. 

Last year, more than 500 million cases of dengue fever were reported globally, along with 5,000 deaths.

Researchers are also growing increasingly concerned at the threat dengue poses to pregnant women, with new evidence emerging that the virus can lead to life-long and even fatal complications for both mothers and babies.

Commenting on whether pregnant women should attend the Rio Carnival, Dr O’Reilly said: “I would be inclined not to go somewhere where the risk is high – but it’s on the individual to make that decision.”

A number of Brazilian states – including Minas Gerias, Acre, and Goias – have also declared public health emergencies in response to the recent dengue outbreak. 

In the capital Brasília, where cases for 2024 have already exceeded last year’s total, the army has been deployed to help track breeding spots of the Aedes aegypti mosquito, which spreads the virus in homes and backyards wherever there is stagnant water.

“It’s well recognised that taking away breeding grounds has an effect,” said Dr O’Reilly. “Even around your property, taking away stagnant water in the bottom of plant pots and old tyres – taking those away will lead to less mosquitos in your area and decrease the risk.”

Brazil also has bought 5.2 million doses of the dengue vaccine Qdenga, developed by Japanese drugmaker Takeda. Brasília will start vaccinating children aged 10-14 on Friday, the local government said.

The World Health Organisation said the current outbreak has been fueled by the El Niño phenomenon that has brought record rainfall to the region, creating conditions for the mosquito population to thrive.

Cases of the disease have also risen sharply in Argentina, where a record 10,000 cases were reported in the first three weeks of the year.

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