Dengue fever has been spreading in Brazil since the start of this year, perhaps due to El Niño, and as of April, it has killed more than 1,000 people. In the whole of 2023, there were 1,079 deaths from dengue. The São Paulo City Department of Health announced that the number of cases in January had risen to 1.6 times the number in the same period last year. Cases have only continued to rise since then.
Dengue is a viral disease transmitted by mosquitoes. The symptoms include sudden high fever, joint pain, headache, and rash. The death rate is very low, but they say that dengue hemorrhagic fever can result in death if it is not properly treated. There is no specific drug for dengue, so an anti-inflammatory painkiller (paracetamol) is used.

In 2015, the Brazilian Health Regulatory Agency (Anvisa) licensed Sanofi Pasteur’s Dengvaxia, a vaccine for dengue, enabling vaccinations in private clinics. Anvisa also approved Qdenga, made by Japanese pharmaceutical company Takeda, in March 2023, making vaccinations available in private clinics. However, free vaccinations of Odenga commenced in January this year under Brazil’s public healthcare system (SUS). The first to be eligible for free vaccination were children aged 10 to 14 years.
On January 20, 757,000 vaccine doses donated by Takeda Pharmaceutical arrived in Brazil. In February, 568,000 more doses arrived, and the Ministry of Health obtained another 5,200,000 doses. Takeda Pharmaceutical later donated 1,320,000 doses.

To help prevent mosquitos from breeding, Brazil’s population at large is being asked on TV and the internet not to leave any tires, empty cans and plastic bottles, buckets, pet food bowls, and the like outside, and to take other measures such as putting sand in plant pot saucers. In 80% of cases, mosquitos breed around homes, so people in homes with a garden or pot plants need to check this carefully. The responsible health authorities are using drones to spray chemical agents onto stagnant water where mosquitoes are likely to be and are spraying insecticide even in alleys. The garbage problem is being raised by TV reports saying that garbage strewn about in the city is contributing to mosquito reproduction. It seems that dengue breaks out every year in March and April, but this year the outbreak started in January, so it is a serious situation with some states declaring a state of emergency.
The best prevention is to avoid being bitten by mosquitos, which means wearing long sleeves and trousers as much as possible, but it is still hot in Brazil, so that seems slightly impossible. They recommend that you put on insect repellent spray or gel when you go outside. And they say insect repellents that contain the ingredient icaridin are better, but products like that sell out straight away at chemists and the like, which has also been reported in the news. Some people are even finding insect-repellent recipes on the internet and making it themselves, but news reports say they are not effective or safe.
Even since the start of April, hospital emergency wards have been crowded with people complaining of fever, headache, and lethargy. I guess a lot of people head for an emergency department when they get a fever because they worry that it might be influenza, COVID, or now dengue. Winter is approaching in Brazil, so I only hope that cases of dengue go on decreasing.