People who have had dengue are twice as likely to develop Covid-19 symptoms. This is what a study carried out by researchers at the Institute of Biomedical Sciences at the University of São Paulo (ICB-USP) points out. Blood samples from 1,285 residents of the municipality of Mâncio Lima, in Acre, were analyzed, where the group works in the investigation of other diseases.
The motivation for the research came from two studies, one American and the other Brazilian, which suggested that previous dengue infection could be a protective factor against the coronavirus.
Therefore, the first step of the study by USP was to verify the presence of antibodies against the dengue virus in samples from October 2019 and Covid-19 in November 2020, through serology tests with the same people analyzed. Researcher Vanessa Nicolete, lead author of the study, explains that the possibility of a cross-reaction has been ruled out and why people who have been infected with dengue are more likely to be symptomatic for the coronavirus.
Age is another relevant factor that was considered in the study. In general, the older you are, the more likely you are to have been exposed to dengue. “As we see in the general population, all ages are predisposed to have antibodies. However, in relation to the infection by Sars-Cov-2, the oldest ones were the ones who presented more symptoms during the research”, affirms Vanessa.
Researchers still do not know what the causes of the phenomenon are, but they point to two hypotheses. One of them would be biological: antibodies against the dengue virus could somehow be favoring the worsening of Covid-19. The other is sociodemographic: populations would be more vulnerable to the two diseases due to different characteristics.
According to the specialist in dengue, Werciley Vieira Junior, the Covid-19 hyper virus stimulates the immune system by producing cytokines, which are inflammatory proteins. “Dengue hypersensitizes our ability to produce these proteins and, therefore, favors a more intense inflammatory process in Covid-19. And, automatically, with the more intense inflammatory processes, the symptoms are greater”, he explains.
How to differentiate dengue from Covid-19?
Many people often confuse the initial symptoms of Covid-19 with dengue. Werciley Vieira Júnior explains the reason for this association between the diseases. “The initial symptoms of Covid-19 are a flu condition that can come with myalgia, which is pain in the body, it can come with headache and joint pain. And dengue is marked by fever, body pain and joint pain. But the proportion of joint pain is much higher in dengue than in Covid-19, and dengue fever is much higher.”
Everyone Against Dengue: campaign encourages public school students to fight the disease
City of Viana (ES) starts vaccinating population with half a dose of AstraZeneca
Know how to differentiate the flu from Covid-19
Dengue is transmitted to humans from the bite of the Aedes Aegypti mosquito that develops in stagnant water. In the case of places with high incidence, such as Acre, the specialist in dengue also highlights some points to increase protection against the disease. “Using repellent and mosquito netting to prevent the entrance of the mosquito already helps. But the best way is to reduce breeding sites, following the guidelines to avoid standing water and avoid throwing garbage where it shouldn’t. By inhibiting the breeders, we decrease the mosquito’s proliferation rate.”
The dengue mosquito lays its eggs in containers such as empty cans and bottles, tires, gutters, uncovered water tanks, dishes under plant pots or any other object that can store rainwater. The mosquito can also look for natural breeding sites, such as bromeliads, bamboo and holes in trees.
According to the Epidemiological Bulletin No. 21 of the Ministry of Health, Brazil currently has 348,508 cases of dengue. In comparison with the year 2020, there was a reduction of 57.4% of cases registered for the same period analyzed. This decrease may be a consequence of the population’s fear of seeking care at a health unit during the Covid-19 pandemic, as well as a possible delay in the notification of diseases by the surveillance and assistance teams to fight the pandemic.
Ranking of dengue cases in Brazil (by incidence)
|Condition||Condition||Cases||incidence (cases/100 thousand inhab.)|
|3||Mato Grosso do Sul||11071||394,1|
|18||Rio Grande do Sul||7618||66,7|
|19||large northern river||1353||38,3|
|24||Rio de Janeiro||1972||11,4|
Of this total, 152 cases of severe dengue (GD), 1,984 cases of dengue with warning signs (DSA) and 105 deaths were confirmed.