Why are dengue cases multiplying in Europe? – 12/25/2023 – Balance and Health

If any of us looked for information about dengue in books or on the internet, we would most likely find it classified within the group known as tropical and subtropical diseases.

And, with the same probability, in recent months, we would have come across news about one of the most intense historical peaks of the epidemic (both in number of cases and deaths) ever recorded in Peru, which declared a state of emergency in most of its regions .

With subtropical and tropical climates, the South American country experiences a significant intensification in the circulation of the virus year after year.

The same happens in Brazil, which led the number of dengue cases in the world, with 2.9 million registered in 2023, according to the World Health Organization (WHO).

The cases are more than half of the 5 million registered worldwide.

Starting in February, Brazil will have the first vaccine against dengue offered by the Unified Health System (SUS).

Qdenga (TAK-003) is an immunizer against dengue developed by the Japanese laboratory Takeda Pharma. The registration was approved by the National Health Surveillance Agency (Anvisa) in March this year.

Record cases in 2023

We would also have recently found news about the disease outside Latin America: records of new autochthonous (non-imported) cases in the United States, Italy or France, as well as the emergence of the first over the years in Spain: in the regions of Catalonia, Ibiza, etc.

Last year, 2.8 million cases of dengue were registered on the American continent alone, which represents a number almost twice as high as the 1.2 million notifications registered in 2021.

Although the disease mainly occurs in tropical and subtropical areas of America, Asia and Africa, in recent years a significant increase has been observed in more temperate areas, such as Europe.

And mainly in the south of the continent, where the disease has been present since the 1970s.

According to data from the European Center for Disease Prevention and Control (ECDC), 71 cases of locally acquired dengue fever were reported in 2022 in the continental part of the European Union.

This represents an increase of no less than 20% compared to 2021.

Last Friday (22/12), the WHO drew attention to the fact that dengue has spread to countries where it historically did not circulate.

What is happening?

Bites with serious consequences

Dengue is a disease caused by one of four serotypes (DENV1, DENV2, DENV3 and DENV4) of the dengue virus (DENV). This pathogen belongs to the family Flaviviridae and it has been reported that the four serotypes can circulate together and cause the same clinical picture.

Dengue hemorrhagic fever deserves special attention, as it is usually triggered after exposure to one of these virus serotypes after having previously been exposed to another.

DENV is transmitted by the bite of infected Aedes mosquitoes, mainly Aedes aegypti and, to a lesser extent, Aedes albopictus. These insects, which feed on human blood and can transmit the virus through saliva, are found in tropical and subtropical areas around the world.

Although, as we pointed out, they have spread to more temperate areas in recent decades.

Thus, virus transmission follows a human-mosquito-human cycle. When a female Aedes mosquito infected with DENV bites a person, she introduces DENV and begins the cycle within the human being. The incubation period is usually 3 to 10 days, although it varies depending on environmental factors such as temperature.

The disease then begins to develop. It usually starts with fever, headache, muscle discomfort, joint pain, nausea and vomiting. In severe cases, it can cause bleeding, organ failure and death.

Aedes mosquitoes breed in stagnant water, such as water containers, unused swimming pools, old tires, etc.

Therefore, in places where there are no effective vaccines and treatments, it is important to eliminate mosquito breeding sites to prevent the transmission of the disease.

But not just dengue fever, as these insects also act as vectors for the transmission of zika and chikungunya.

Climate change and globalization

Climate change is one of the factors contributing to the increase in dengue cases, both in America and Europe.

Rising temperatures and the length of the mosquito season (due to hotter and longer summers) may favor the proliferation of Aedes aegypti.

These mosquitoes are able to survive in temperatures above 10 degrees Celsius and, with global warming, may expand their range to more temperate areas. And, by causing changes in rainfall patterns, climate change increases the volume of stagnant water, an ideal habitat for its reproduction.

In addition, the increase in international travel and trade (people who travel to areas with dengue fever can contract the infection and transmit it when they return to Europe).

The growth of cities also creates favorable conditions for the reproduction of these mosquitoes.

Are we on the path to Europe becoming an endemic region?

With this panorama, the possibility of dengue becoming an endemic disease on the Old Continent is a real scenario: environmental conditions – climate change and globalization – are increasingly favorable to the activity of the vector and the replication of the virus within it.

Furthermore, these are factors that are currently beyond human control.

If dengue becomes an endemic disease in Europe, it could have a significant impact on public health.

For this reason, European health authorities are already working to prevent its spread with measures on factors that can be controlled, such as case surveillance, education on how to prevent mosquito bites, and the application of critical population control measures. of mosquitoes from the moment their presence is detected.

Something that, for example, has happened quite frequently on the Spanish island of Tenerife.

You can’t be too careful.

This text was originally published here.