Brazil reached the end of 2022 with a sad record: 1.016 Brazilians died from dengue, as reported by the Epidemiological Bulletin of the Ministry of Health. It is the highest number of deaths from the disease ever recorded since the beginning of the report.
The discharge of fatal cases, usually associated with late diagnosis of the disease, may be related to the diversion of attention to mitigating the health urgency caused by Covid-19.
“If we look at the data that preceded the pandemic, we realized that, during increases in dengue cases, the number of deaths still remained in smaller proportions, since patients were diagnosed more quickly and, consequently, treated appropriately”, highlights Denise Valle, from the Flavivirus Molecular Biology Laboratory at the Oswaldo Cruz Institute (IOC/Fiocruz).
The initial clinical manifestations of dengue are common and can be confused with other diseases, including Covid-19: fever, headaches and body aches, malaise and weakness. The similarity of symptoms may have confused both the population and health professionals.
“The lethality of dengue is associated with the delay in identifying and treating the disease. In the last year, still under the influence of Covid-19, patients who were following social isolation may have taken longer to seek medical assistance, and many may have received an inaccurate diagnosis due to the presence of another disease with similar symptoms”, he comments.
The Aedes aegypti mosquito. Photo: Joshua Damacena
As transmitted by Aedes aegypti (also a vector of the chikungunya and Zika viruses), dengue has its general number of cases directly influenced by the number of mosquitoes.
Researcher Rafaela Bruno, head of the Laboratory of Molecular Biology of Insects at the IOC, recalls that in recent years preventive care has also been in the background.
“The number of awareness campaigns about the Aedes and, therefore, many people forgot to inspect their homes in search of stagnant water. Also, with social distancing, endemic agents were not authorized to visit homes for prevention actions, which are fundamental to remind residents of the importance of eliminating mosquito breeding sites,” he points out.
In 2022, 1.450.270 probable cases of dengue were registered. Other numbers that draw attention are those of probable cases of Chikungunya and Zika.
There was an increase of 78,9% in the count of Chikungunya cases in 2022 when compared to the same period in 2021 – which was already 32,7% higher than the previous year. In cases of Zika, the increase was 42%.
“These numbers may decrease from this year onwards with the dynamics of society resembling the pre-pandemic period. However, this will only happen if we also recover our awareness actions about the Aedes aegypti”, says Rafaela.
To prevent the severity scenario from repeating itself in 2023, the researchers warn of the importance of maintaining regularity in prevention campaigns.
Known by the Brazilian population, the campaign '10 Minutes Against Aedes' – which for more than a decade has helped guide prevention care – remains the main tool to reduce mosquito incidence.
“It is a campaign with a simple and concrete message, easy to understand and execute. Since 2009, when it was launched, it has been our great ally to drastically reduce mosquito infestation and, consequently, reduce cases of diseases transmitted by them”, recalls Denise.
Weekly action guide included in the '10 Minutes Against Aedes' campaign booklet. Foo: Playback
The '10 Minutes Against Aedes' aims to encourage the population to dedicate at least 10 minutes a week to inspect their homes in search of possible mosquito breeding sites.
“We have to recover the attention that prevention against Aedes had and, for that, we need the active cooperation of opinion multipliers, such as community leaders and journalists”, says Denise.
“We need to reverse the significant drop in the number of public campaigns and insertions in the media and return to occupy communication spaces so that the population is reminded of the actions that must be taken against the Aedes”, reinforces Rafaela Bruno.
Discover and share booklet of the '10 Minutes Against Aedes'.
The development of Aedes aegypti is accelerated in places where there is heat and stagnant water supply. And the most favorable season for this scenario is summer – with high temperatures and frequent rain showers.
At the beginning of this year, some regions of Brazil had milder weather than expected for the season, a fact that may slightly delay the cycle of the mosquito, which passes from the egg to the adult stage between 7 and 10 days. However, the large volume and frequency of rainfall contribute to the emergence of new breeding sites.
“The female of Aedes can lay up to 1.500 eggs, spread across different locations. The cooler climate does not give us reason to relax”, warns Denise.
The easiest way to avoid cases of disease transmission is to interrupt the mosquito's life cycle in its aquatic form (egg, larva and pupa). This action must be performed weekly.
“Disrupting this process helps to significantly reduce the incidence of disease. It's important that we all set aside one day a week and, for at least 10 minutes, look for places that can be breeding grounds inside and around the house”, says Rafaela.
Aedes aegypti mosquito eggs: a single female is capable of generating thousands of new mosquitoes. Photo: Joshua Damacena
The main recommendation is to prevent places from accumulating water. As examples, potted plants, air-conditioning trays, little-used swimming pools, barrels, buckets, recyclable bottles and unstretched canvas can be highlighted.
“We can say that the Aedes it is a domestic mosquito, because out of every ten breeding sites, eight are in homes. Therefore, we have to look at the house with 'mosquito eyes', because the breeding sites are not always in the most obvious places”, signals Denise.
The less conventional places to stop and that are great for the Aedes depositing their eggs are rain gutters, external drains, pet bowls and refrigerator trays.
“It is much easier to eliminate eggs, pupae and larvae, which are restricted to a physical environment, than to go after the flying mosquito”, highlights Denise.
However, it is not always possible to do away with containers that accumulate stagnant water.
“There are several different scenarios within Brazil. There are populations that live in regions with difficult water supply, where it is necessary to stock up. Accumulation of water and high temperature is all that the female Aedes want to lay their eggs”, points out Rafaela.
The guideline, in these more specific cases, is that the containers are properly sealed.
“When standing water cannot be disposed of, it is important to be even more attentive and constantly inspect the containers. It is important that they are covered, or protected with a screen, preventing the female mosquito from entering and depositing her eggs there”, says Rafaela.
The researcher also points out that, when it comes to prevention, creativity is an ally.
“One of our recommendations is that drains be covered with screens or mosquito nets. However, not everyone has access to these materials. I've seen residences that used pantyhose as a solution. When it comes to prevention, any help is welcome. In this situation, it is also important to check frequently that the fabric is not torn or perforated, and that the seal is correct”, says Rafaela.
Learn More ways to prevent Aedes aegypti.
The use of repellents is important as a form of individual prevention, especially for pregnant women, the elderly and children - groups considered at risk for diseases transmitted by the virus. Aedes. It is worth remembering that the effectiveness of these products depends on several factors, so it is essential to read the packaging label.
It is also important to highlight that repellents only work when applied to the body and are not effective if used on objects, clothing or furniture.
“The use of repellent does not help to improve the general situation and reduce the number of mosquitoes, so it should only be considered as a complementary action, not as a substitute for eliminating breeding sites”, emphasizes Denise.
Featured, mosquito Aedes aegypti, vector of dengue, Zika and chikungunya. In the background, Aedes pupae, a stage prior to the winged phase of the mosquito. Photo: Joshua Damacena
Chemical control, with the use of insecticides and larvicides, is also not the main focus of prevention. The method is also recommended as a complementary measure and, in this case, it must be administered exclusively by the public authorities.
“The Ministry of Health uses insecticides based on rigorous planning. If the entire population decides to use them at random, we will have a loss of effectiveness for these products, which will lead to an increase in resistant mosquitoes”, warns Denise.
“In the beginning they can even kill a large number of insects, because most of them will still be susceptible to chemical control. However, the resistant ones will remain that will give rise to new mosquitoes, which will also be resistant. If that happens, in a short time, the insecticides will no longer work”, he adds.
Thus, the most efficient measure continues to be the elimination of larvae and eggs.
“In the mechanical method, we are preventing the evolution of all mosquitoes, regardless of whether they are resistant or not”, reiterates the researcher.
Despite affecting the general population, the incidence of arbovirus transmission is often related to uncontrolled urbanization and lack of access to basic rights such as water and basic sanitation.
“The focus of prevention actions is on Aedes aegypti. However, it is not just the mosquito's fault. When we look at our cities, we see several regions without water supply, basic sanitation and regular garbage collection. It is necessary for the government to resolve these issues as well, in addition to combating the mosquito”, emphasizes Denise.
The researcher claims that urbanization and better housing conditions have a significant contribution to the reduction of cases of diseases transmitted by the virus. Aedes.
“We can come up with a number of innovative techniques and creative solutions to combat the Aedes, however, as long as these social problems remain, we will continue to encounter difficulties in fighting the mosquito. In addition, precarious housing conditions make people vulnerable not only to arboviruses, but also to numerous other diseases. The solution for dengue, chikungunya and Zika involves citizenship”, concludes Denise.
Brazil reached the end of 2022 with a sad record: 1.016 Brazilians died from dengue, as reported by the Epidemiological Bulletin of the Ministry of Health. It is the highest number of deaths from the disease ever recorded since the beginning of the report.
The discharge of fatal cases, usually associated with late diagnosis of the disease, may be related to the diversion of attention to mitigating the health urgency caused by Covid-19.
“If we look at the data that preceded the pandemic, we realized that, during increases in dengue cases, the number of deaths still remained in smaller proportions, since patients were diagnosed more quickly and, consequently, treated appropriately”, highlights Denise Valle, from the Flavivirus Molecular Biology Laboratory at the Oswaldo Cruz Institute (IOC/Fiocruz).
The initial clinical manifestations of dengue are common and can be confused with other diseases, including Covid-19: fever, headaches and body aches, malaise and weakness. The similarity of symptoms may have confused both the population and health professionals.
“The lethality of dengue is associated with the delay in identifying and treating the disease. In the last year, still under the influence of Covid-19, patients who were following social isolation may have taken longer to seek medical assistance, and many may have received an inaccurate diagnosis due to the presence of another disease with similar symptoms”, he comments.
The Aedes aegypti mosquito. Photo: Joshua Damacena
As transmitted by Aedes aegypti (also a vector of the chikungunya and Zika viruses), dengue has its general number of cases directly influenced by the number of mosquitoes.
Researcher Rafaela Bruno, head of the Laboratory of Molecular Biology of Insects at the IOC, recalls that in recent years preventive care has also been in the background.
“The number of awareness campaigns about the Aedes and, therefore, many people forgot to inspect their homes in search of stagnant water. Also, with social distancing, endemic agents were not authorized to visit homes for prevention actions, which are fundamental to remind residents of the importance of eliminating mosquito breeding sites,” he points out.
In 2022, 1.450.270 probable cases of dengue were registered. Other numbers that draw attention are those of probable cases of Chikungunya and Zika.
There was an increase of 78,9% in the count of Chikungunya cases in 2022 when compared to the same period in 2021 – which was already 32,7% higher than the previous year. In cases of Zika, the increase was 42%.
“These numbers may decrease from this year onwards with the dynamics of society resembling the pre-pandemic period. However, this will only happen if we also recover our awareness actions about the Aedes aegypti”, says Rafaela.
To prevent the severity scenario from repeating itself in 2023, the researchers warn of the importance of maintaining regularity in prevention campaigns.
Known by the Brazilian population, the campaign '10 Minutes Against Aedes' – which for more than a decade has helped guide prevention care – remains the main tool to reduce mosquito incidence.
“It is a campaign with a simple and concrete message, easy to understand and execute. Since 2009, when it was launched, it has been our great ally to drastically reduce mosquito infestation and, consequently, reduce cases of diseases transmitted by them”, recalls Denise.
Weekly action guide included in the '10 Minutes Against Aedes' campaign booklet. Foo: Playback
The '10 Minutes Against Aedes' aims to encourage the population to dedicate at least 10 minutes a week to inspect their homes in search of possible mosquito breeding sites.
“We have to recover the attention that prevention against Aedes had and, for that, we need the active cooperation of opinion multipliers, such as community leaders and journalists”, says Denise.
“We need to reverse the significant drop in the number of public campaigns and insertions in the media and return to occupy communication spaces so that the population is reminded of the actions that must be taken against the Aedes”, reinforces Rafaela Bruno.
Discover and share booklet of the '10 Minutes Against Aedes'.
The development of Aedes aegypti is accelerated in places where there is heat and stagnant water supply. And the most favorable season for this scenario is summer – with high temperatures and frequent rain showers.
At the beginning of this year, some regions of Brazil had milder weather than expected for the season, a fact that may slightly delay the cycle of the mosquito, which passes from the egg to the adult stage between 7 and 10 days. However, the large volume and frequency of rainfall contribute to the emergence of new breeding sites.
“The female of Aedes can lay up to 1.500 eggs, spread across different locations. The cooler climate does not give us reason to relax”, warns Denise.
The easiest way to avoid cases of disease transmission is to interrupt the mosquito's life cycle in its aquatic form (egg, larva and pupa). This action must be performed weekly.
“Disrupting this process helps to significantly reduce the incidence of disease. It's important that we all set aside one day a week and, for at least 10 minutes, look for places that can be breeding grounds inside and around the house”, says Rafaela.
Aedes aegypti mosquito eggs: a single female is capable of generating thousands of new mosquitoes. Photo: Joshua Damacena
The main recommendation is to prevent places from accumulating water. As examples, potted plants, air-conditioning trays, little-used swimming pools, barrels, buckets, recyclable bottles and unstretched canvas can be highlighted.
“We can say that the Aedes it is a domestic mosquito, because out of every ten breeding sites, eight are in homes. Therefore, we have to look at the house with 'mosquito eyes', because the breeding sites are not always in the most obvious places”, signals Denise.
The less conventional places to stop and that are great for the Aedes depositing their eggs are rain gutters, external drains, pet bowls and refrigerator trays.
“It is much easier to eliminate eggs, pupae and larvae, which are restricted to a physical environment, than to go after the flying mosquito”, highlights Denise.
However, it is not always possible to do away with containers that accumulate stagnant water.
“There are several different scenarios within Brazil. There are populations that live in regions with difficult water supply, where it is necessary to stock up. Accumulation of water and high temperature is all that the female Aedes want to lay their eggs”, points out Rafaela.
The guideline, in these more specific cases, is that the containers are properly sealed.
“When standing water cannot be disposed of, it is important to be even more attentive and constantly inspect the containers. It is important that they are covered, or protected with a screen, preventing the female mosquito from entering and depositing her eggs there”, says Rafaela.
The researcher also points out that, when it comes to prevention, creativity is an ally.
“One of our recommendations is that drains be covered with screens or mosquito nets. However, not everyone has access to these materials. I've seen residences that used pantyhose as a solution. When it comes to prevention, any help is welcome. In this situation, it is also important to check frequently that the fabric is not torn or perforated, and that the seal is correct”, says Rafaela.
Learn More ways to prevent Aedes aegypti.
The use of repellents is important as a form of individual prevention, especially for pregnant women, the elderly and children - groups considered at risk for diseases transmitted by the virus. Aedes. It is worth remembering that the effectiveness of these products depends on several factors, so it is essential to read the packaging label.
It is also important to highlight that repellents only work when applied to the body and are not effective if used on objects, clothing or furniture.
“The use of repellent does not help to improve the general situation and reduce the number of mosquitoes, so it should only be considered as a complementary action, not as a substitute for eliminating breeding sites”, emphasizes Denise.
Featured, mosquito Aedes aegypti, vector of dengue, Zika and chikungunya. In the background, Aedes pupae, a stage prior to the winged phase of the mosquito. Photo: Joshua Damacena
Chemical control, with the use of insecticides and larvicides, is also not the main focus of prevention. The method is also recommended as a complementary measure and, in this case, it must be administered exclusively by the public authorities.
“The Ministry of Health uses insecticides based on rigorous planning. If the entire population decides to use them at random, we will have a loss of effectiveness for these products, which will lead to an increase in resistant mosquitoes”, warns Denise.
“In the beginning they can even kill a large number of insects, because most of them will still be susceptible to chemical control. However, the resistant ones will remain that will give rise to new mosquitoes, which will also be resistant. If that happens, in a short time, the insecticides will no longer work”, he adds.
Thus, the most efficient measure continues to be the elimination of larvae and eggs.
“In the mechanical method, we are preventing the evolution of all mosquitoes, regardless of whether they are resistant or not”, reiterates the researcher.
Despite affecting the general population, the incidence of arbovirus transmission is often related to uncontrolled urbanization and lack of access to basic rights such as water and basic sanitation.
“The focus of prevention actions is on Aedes aegypti. However, it is not just the mosquito's fault. When we look at our cities, we see several regions without water supply, basic sanitation and regular garbage collection. It is necessary for the government to resolve these issues as well, in addition to combating the mosquito”, emphasizes Denise.
The researcher claims that urbanization and better housing conditions have a significant contribution to the reduction of cases of diseases transmitted by the virus. Aedes.
“We can come up with a number of innovative techniques and creative solutions to combat the Aedes, however, as long as these social problems remain, we will continue to encounter difficulties in fighting the mosquito. In addition, precarious housing conditions make people vulnerable not only to arboviruses, but also to numerous other diseases. The solution for dengue, chikungunya and Zika involves citizenship”, concludes Denise.
The non-profit reproduction of the text is allowed as long as the source is cited (Comunicação / Instituto Oswaldo Cruz)
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