The increase in dengue fever in the state of São Paulo requires greater compliance with protective measures – Jornal da USP

The infectiologist Marcos Boulos comments on the growth of dengue fever and recalls that stagnant water is responsible for the proliferation of the Aedes aegypti mosquito.


With the rains, there is a risk of greater proliferation of Aedes, the mosquito that transmits dengue fever Photo: Pixabay

The number of dengue cases in the state of São Paulo is increasing. In 2022, they were 107,000 compared to 104,000 in 2021. The number has increased not only in cases of illness, but also in deaths, which rose from 44 to 77 in the first four months of this year alone. In the capital, there has also been a significant increase, with 3,129 cases. In January this year, there were 224 confirmed cases, rising to 1,353 in April alone. According to Marcos Boulos, a senior professor in the Department of Infectious and Parasitic Diseases at USP School of Medicine, dengue fever is a seasonal disease and, despite the outbreak, it has not occurred as intensely as in previous years.

“It usually appears in summer, when it’s very hot or when it rains a lot. With the rains, you have a greater proliferation of Aedes, the transmitting mosquito, and you can have greater transmissibility. By a very By coincidence, in the past two years, the number of dengue fever cases has been lower than before. The professor explained that in the pandemic, there was a decrease. “We don’t have any appropriate explanation for this.People who stay at home more often should have probably been more careful, avoiding standing water.

Marcos Boulos – Photo: Secretary of State for Health

The increase in the number of cases in Greater São Paulo is due to poor housing conditions, many people living in places with stagnant water and less urban infrastructure. The north of the state of São Paulo generally presents a greater infestation of the disease. The professor recalls that “it is traditional for São José do Rio Preto and Ribeirão Preto, where the heat is greater and it rains more, to be at the top of the number of dengue fever cases in the state”.

Dengue fever only appears because there is still water, an ideal place for the female to lay eggs, causing the proliferation of Aedes aegypti. Avoiding stagnant water and constant cleaning are the key to avoiding mosquito breeding sites, since 80% of outbreaks occur inside homes. Professor Boulos recalls that, “in the case of public services, parks, schools and cemeteries must be inspected, taking great care to avoid breeding places”.

A curiosity: anyone who has had a type of dengue fever will never have the same type of infection again, quotes Marcos Boulos. It should be remembered that there are four different types of the disease, so the risk is greater for those who have had it. If the person has a sequence of infections, becoming ill within six months to three years, they may have more severe cases.

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