RIO DE JANEIRO — The authorities in the Brazilian city of Rio de Janeiro have declared a health emergency as they try to contain the spread of dengue fever.

The incidents of the mosquito-borne disease quadrupled in Brazil in January compared to the same month last year.

Rio has registered 10,000 cases so far this year, compared to 23,000 for the whole of 2023.

Dengue can cause a fever, severe headache, pain behind the eyes, muscle and joint pain, and a blotchy rash.

Rio city hall announced it would open 10 treatment centers for people with dengue.

Daniel Soranz, the city's health secretary, said the aim was to reduce the number of serious cases and deaths caused by the infection. "Early treatment makes all the difference," he said.

Health officials have also urged people to prevent being bitten by mosquitos by applying repellent.

Brazil's Health Minister Nísia Trindade has urged people to make sure they check their homes and get rid of any stagnant water, where the mosquitos which transmit dengue breed.

Fumigators are spraying some of the worst affected areas and public health announcements will be made at the Sambadrome, the venue where Rio's famous samba schools parade in front of judges to be crowned winner of this year's Carnival parade. — BBC