With the arrival of cold days, especially in the central area of the country, the presence of mosquitoes decreased significantly. However the dengue is still among us.
According to the last Epidemiological Bulletin of the Ministry of Health of the Nation, which covers from the beginning of the season in week 31 of 2023 -end of July- until mid-April 2024, a total of 396,484 cases. Of this figure, 379,341 infections correspond to 2024. Among these numbers, the 871 infections classified as severe denguewhich represent 0.2% of the total reported cases, and the 280 deathswhich marks a lethality of 0.071%.
The surveillance of the viral disease transmitted by the mosquito Aedes aegypti It is carried out seasonally, from epidemiological week 31 of one year to week 30 of the next, coinciding with the peak of virus activity, which generally occurs during the summer months. Although there are still several weeks left to complete this year’s measurement, The threshold of record cases registered in the previous season has been widely exceededwhich stood at just over 130 thousand.
Although in the latest records a decline in the number of weekly cases, we speak of a historic dengue outbreak. Because? In addition to the figures already mentioned, in the document issued by the health portfolio there are at least three fundamental characteristics to answer this question. Or rather, there are four parallels.
“Compared to other epidemic years, the current season is characterized by a greater magnitude than previous epidemic seasons: the accumulated cases until EW16 represent 3.25 times more than what was registered in the same period of the previous season -2022/2023- and 9.24 times more than what was recorded in the same period of 2019/2020; persistent viral circulation throughout the period in the NEA region and earlier seasonal increase compared to previous epidemic years; and greater number of cases per week: with the information available so far, since week 8 of 2024 – mid-February – the number of cases has exceeded the previous peak recorded in week 13 of 2023 – end of March 2023-, when 18,211 cases had been recorded,” they specified.
For review the three characteristics of the historical dengue outbreak, according to the Epidemiological Bulletin:
- Persistent viral circulation throughout the period in some provinces
- Advancement of seasonal increase compared to previous records
- Higher number of cases per week.
What are the factors that explain this situation? Recently, when asked by Infobae, The infectologist Rogelio Pizzi, dean of the Faculty of Medical Sciences of the National University of Córdoba (UNC) and head of the Latin American and Caribbean Association of Faculties and Schools of Medicine (Alafem), gave some details in this regard.
“The increase in temperatures and changes in rainfall regimes favor mosquito adaptation, turning a seasonal disease into a constant threat. Today, the majority of cases are indigenous, unlike before, when imported cases were recorded from people traveling to endemic areas. “The viral circulation in provinces with climates and areas previously considered unlikely, such as Cuyo or northern Patagonia, underlines the adaptability of the mosquito to different climatic conditions,” Pizzi said.
And he added: “Mosquito eggs can be viable and resist adverse conditions for up to a year, and then hatch under favorable temperature and humidity conditions. The presence of Aedes aegypti does not require large amounts of water to reproduce; A simple cap of soda or a drop of water is enough for it to lay its eggs. It is vital to comply with health standards for cleaning and weeding at home to prevent the reproduction of the mosquito and thus avoid the transmission of the disease.”
In the same article, Julian Antman, epidemiologist and former coordinator of the Dengue Prevention Plan in the Federal Capital, contributed his perspective in dialogue with Infobae: “This year, unlike others, in the NEA, in provinces such as Misiones, Formosa and Chaco, there were cases of dengue throughout the year, a novelty compared to previous years. “This has resulted in many people being infected by two serotypes of dengue, which has worsened cases and increased deaths, exceeding 100. This is especially serious and suggests the possibility of more cases than last season.”
“General factors include climate change, which allows the mosquito to adapt to colder temperatures, while as humanity we increase temperatures. Autochthonous cases have been recorded even in La Pampa and Mendoza, due to this adaptability of the mosquito to lower temperatures. This, along with internal migration, increases the possibility of cases throughout the country, as people move from regions with high incidence to others where the vector is present, triggering outbreaks,” Antman said.
“We observed that there are regions of the country that did not have cases last year and now do,” the epidemiologist added, “due to the presence of the Aedes aegypti vector and the circulation of the dengue virus. Currently, the most prevalent serotypes are Dengue one and Dengue two, with very little circulation of serotype three, limited to Córdoba. “This increases susceptibility and therefore the possibility of dengue in different locations.”
For his part, in a recent note to Infobae, Ricardo Gurtlerresearcher at the Institute of Ecology, Genetics and Evolution of Buenos Aires, which depends on the Conicet and the Faculty of Exact and Natural Sciences of the Buenos Aires’ University, He specified: “There was a spill from Brazil, which has a high incidence of dengue cases, to other countries in the Southern Cone and to other regions of America. But we must also consider that Argentina has a very strong exchange with Paraguay and Bolivia. There were epidemic outbreaks there this year and that also impacts our country.”
“Another factor is the increase in temperature and the change in the rainfall regime that can influence the problem of dengue. But there can also be years with droughts, which also influence. Because water is stored inadequately and thus favors the creation of gigantic mosquito breeding sites”Gurtler added.
In recent weeks, there has been a decrease in temperature in some regions of the country, something that experts relate to the possibility of a reduction in dengue cases, as long as this dynamic is maintained for a few weeks.
However, there are species of mosquitoes that are still active today, which highlights the importance of preventing the presence of the mosquito. Aedes aegyptiwhich is the vector that transmits the dengue virus, in our homes.
With the approach of winter, specialists emphasize the need to maintain preventive measures to avoid the reproduction of these mosquitoes, such as eliminating any container that may contain stagnant water and protecting homes with mosquito nets, among other actions.
“All epidemiological outbreaks have dynamics, that is, they begin, cases increase rapidly until they reach their peak, then they stabilize and begin to decrease. That is normally what happens in any epidemic outbreak situation. Here, the situation is absolutely transitory. Mosquito activity decreased somewhat when the temperature was cold or relatively cold; tempered. The mosquito not only decreases its activity, but also “Leave the surroundings of the house and enter the home.”he recently told Infobae andthe doctor Hugo Pizzi, infectious disease doctor, epidemiologist and professor at the National University of Córdoba.
“You have to be very careful in these circumstances, since the mosquito can be behind the curtains or in different places inside the house. So, this doesn’t mean the problem is solved; On the contrary, activity has decreased a little, but we are already seeing that cases are increasing again with the return of the heat,” added the expert.
“There are many female mosquitoes infected with the dengue virus that lay eggs,” the infectious disease specialist continued. Those eggs are already infected with the virus. That is to say that within five or six months, when there are heat strokes, the new mosquitoes will hatch and the infected females will come out with the virus. This will continue to accumulate and increase the negative aspects of any epidemiological outbreak. Therefore, the concept is that there has been a decrease in cases, and it is true that mosquito activity has gone down, but with the return of the heat, cases are starting to increase again.”
