ASEAN: Caution Against the Asian Tiger Mosquito

BERLIN – Returning from a long journey and suddenly experiencing high fever? It could be a case of imported dengue infection. In Germany, the number of cases is on the rise.

Dengue viruses are transmitted by certain species of mosquitoes – mainly the yellow fever mosquito and the Asian tiger mosquito. Specimens that transmit dengue viruses are primarily found in tropical regions of Asia, South America, and Africa.

An increasing number of travelers are bringing dengue fever back home, as data from the Robert Koch Institute (RKI) shows. Accordingly, 737 cases of dengue were reported in Germany in the first 17 weeks of this year. Last year, there were 174 cases in the same period. The authority explains this development in its “Epidemiological Bulletin” as due to increased case numbers in many countries.

Tourists in Indonesia and Thailand at risk

Brazil is one example. Since the beginning of the year, more than five million infections with the dengue virus have been registered there – the largest outbreak to date in the South American country. Besides Brazil, Indonesia, and Thailand are among the countries from which the most return travelers brought dengue back to Germany in the first 17 weeks of this year, as RKI data indicates.

A global overview of current dengue fever outbreaks can be found on the website of the European Centre for Disease Prevention and Control (ECDC).

It is important to know beforehand: Only about one in four infections is accompanied by symptoms of illness, as stated by the CRM Centre for Travel Medicine.

Pay attention to the following signs: sudden, high fever, body aches, and headaches (which feel like they are right behind the eyes), extensive skin rashes that look like sunburn.

According to Tomas Jelinek, scientific director of the CRM, the fever usually subsides on its own after four to five days. If it persists or occurs in waves, this speaks against dengue.

The incubation period is usually around 4-7 days

This also applies if symptoms only appear more than two weeks after returning from travel. This is because the incubation period is typically four to seven days, but in rare cases, it can be longer.

A small percentage of those affected – one percent, according to the CRM – experience severe courses of the disease. The reason for this is that the infection makes fine blood vessels permeable. This allows fluid to enter the blood from the tissue. Warning signs for this are abdominal pain, persistent vomiting, shortness of breath, or bleeding of the mucous membranes, such as the gums.
Severe courses can be fatal if left untreated.

Especially around the fifth day of illness, one should pay attention to whether these complaints occur, advises the CRM. If severe courses remain untreated, they can be fatal.

Good to know: A severe course is rare during the first Dengue infection. However, having had the disease does not mean immunity for the rest of one’s life. Since there are four variants of the Dengue virus, one can be reinfected – the second, third, or fourth infections often have a more severe course.

How can travelers prevent infection?

Those traveling to an area where Dengue is transmitted need good mosquito protection. The mosquitoes that transmit the disease are predominantly active during the day. Travelers can protect themselves from bites with the help of repellents that are applied to the skin and keep mosquitoes away, according to the CRM. Long clothing also protects – preferably in light colors, as mosquitoes are more attracted to dark colors.

There are two vaccines against Dengue fever – including one that is suitable for travelers. The European Medicines Agency (EMA) approved the vaccine Qdenga at the end of 2022, for adults and children from the age of four.

In November 2023, the Standing Committee on Vaccination (Stiko) decided on vaccination recommendations for Qdenga. They recommend the vaccine only for travelers who have had a confirmed case of Dengue infection in the past. The vaccination consists of two doses administered at a minimum interval of three months. (dpa)