Dangerous mosquitoes in EuropeMaayk
Let’s start small.
30 types of mosquitoes can be found in the Netherlands alone. Some examples are: the traditional stinging mosquito, the crane fly, the moth mosquito and the dancing mosquito. Most mosquitoes suck blood. They get their name from the fact that females suck blood, which is what they need for the maturation of their eggs. They belong to the Culicidae and can be found all over the world. Some pick-up diseases which can than be transferred the next time they sting. Since the 1960s we no longer have malaria in the Netherlands and until recently there were no dangerous diseases being transmitted by mosquitoes within the Netherlands. But times change.
We have all started to travel more and our lives have become more global. The exotic mosquitoes, which we hardly saw until 10 years ago are participating in this movement. We must therefore think more broadly. That is why we do not focus on one country in this story, but in different countries in Europe and beyond.
The news is increasingly reaching us that other new exotic mosquitoes have been spotted. We read alarming reports from Spain, Italy, Switzerland and parts of Southern Germany. Some even refer to the Asian tiger mosquito as a “well-established guest”.
Tiger mosquito in Europe
At first the exotic mosquitoes enter Europe via international transport. Then, when these “strange” mosquitoes settle in our climate, we speak of invasive exotic mosquitoes. An example of this is the Asian bush mosquito, who travels in used car tires and lucky bamboo plants. Another example is a more dangerous specimen, the Tiger mosquito. Until a while ago, the chance that it could transmit dengue or Zika fever was negligible. But that is also changing.
Last year at a European congress on infectious diseases (ECCMID), no fewer than 13,500 doctors from 127 countries gathered to discuss the consequences of climate change on the arrival of exotic mosquitoes. With increasingly extended periods of warm weather, less cold winters and more significant amounts of rain, the Mediterranean is now becoming a tropical region for certain parts of the year. The exotic mosquitoes thrive in this climate, and diseases such as dengue (dengue fever) or encephalitis are getting increasingly more common. For example, the Portuguese Island of Madeira was ravaged by the yellow fever mosquito in 2012. Or Greece, which was hit by a Malaria outbreak that same year.
Since 2018, the West Nile virus, transmitted by mosquitoes, has also been a threat to Southern (Eastern) European countries. This dangerous virus is spread by ordinary mosquitoes, which can be found everywhere in the Netherlands and the rest of Europe. Originally, the virus only occurred in the countries around the River Nile, but it has spread over many parts of the world in recent decades. Besides the fact that the West Nile virus is common in Italy and Eastern Europe, it has now also manifested itself in the Netherlands and other Western European countries.
Of the people who have West Nile fever, 80% have few complaints. 20% suffer from mild symptoms such as: fever, headache and muscle pain. However, a small number can develop a serious illness such as encephalitis or meningitis. The chance of death is 4 to 14%. With older people, this can increase to 29%.
How do you get infected with the West Nile virus?
Humans become infected through infected mosquitoes. Mosquitoes, in turn, become infected because they feed on infected birds. Afterwards, the mosquitoes can spread the virus to other birds and sometimes to humans or other mammals. It is not natural for the virus to be passed from person to person. But in the case of blood or organ transplantation, this may be the case.
Recently, the news reported that in Andalusia, Spain, four older people have died of the West Nile virus, and ten people have been hospitalized with this disease. The regional government of Andalusia has therefore sprayed several wetlands with pesticide to prevent the spread of these infected mosquitoes. Most importantly, they have urged the local population to use mosquito nets and insect screens to protect themselves against this virus.
Andalusia is an area where people from all over the world like to go on holiday. It is gorgeous, warm and the people are hospitable. But due to climate changes, it is getting more humid, and so the danger of these mosquitoes has increased. Besides, we -humans- in turn, take the virus back to our own country. In other words, vigilance is no longer only necessary in the tropics, but unfortunately also in Europe.
Another example of a dangerous mosquito that we have known for some time is the malaria mosquito. The word malaria comes from the Latin “mala aria”, which means “bad air”. This bad air refers to the strong odour we can smell in swamps. Malaria that has plagued humanity in Africa for years originally evolved from a variant of malaria found in gorillas. The malaria mosquito has been around for millions of years. And millions of people are still dying from its virus. People infected with malaria have symptoms such as fever, which can get so bad that they can die. It is one of the greatest enemies of the people living in Africa. Young people and large percentages of pregnant women also do not survive the disease, which means that the virus is still having severe economic consequences in large parts of Africa.
source: Mayo Foundation for Medical Education and research (https://www.mayoclinic.org/)
In the case of the malaria mosquito, climate change plays a less important role. Globalisation, on the other hand, increases the chance of a parasites traveling with humans. Besides, the malaria mosquito is not only an exotic species. Long ago, malaria mosquitoes were found in Northern Europe. In the United States, for example, there were 1,000 people infected with malaria in 2014. In principle, the virus is most often combated with medicines. But even here, serious protection such as covering clothing and mosquito nets are essential.
A team from Wageningen University and Research collaborated with TU Delft on new mosquito traps in the fight against malaria, the so-called M-Tego. The trap spreads heat, which attracts the mosquitoes and sucks them into the trap. They are realistic in their research: “It will not eradicate malaria, but it can certainly contribute to a reduction”.
As we mentioned earlier about the Asian Tiger mosquito as a “well-established guest”, this mosquito is also a variant that we must increasingly take into account in Europe. The mosquito is native to Southeast Asia. The mosquito bites mainly during the day and these bites can be experienced as painful. The Asian Tiger mosquito spreads a virus infection called dengue, also known as dengue fever. It can also transmit the Zika virus, but this is less likely. Dengue starts with a fever, headache, and often muscle pain, for eight to ten days. After three to four weeks, there is a possibility of a blotchy rash. You should always seek medical advice if you have a fever in tropical countries. There are no vaccinations or medicines against this virus. For that reason, it is essential that you always protect yourself with covering clothing and a mosquito net.
Travelers to Laos, Cambodia, Thailand, Vietnam or the Philippines, in particular, should be vigilant for the tiger mosquito. They spread very fast in the rainy season. Since 2011, dengue has been very active again and the Philippines has declared it an epidemic. The increase in the number of patients also caused a shortage of blood, which is necessary for the treatment, in some countries.
But even if you do not travel to Asia, the Asian tiger mosquito is now found in Europe. Experts are not yet in agreement on how significant the risk to public health is. The mosquito is mainly seen in Southern Europe, much less in Northern Europe. For example, in the Netherlands in 2010, there was a case at a company in Weert, when 10 mosquitoes were detected.
Some say it is harmless; others see it as alarming. For example, entomologist Bart Knols, affiliated with Radboud University, speaks about the fact that we simply know too little about the exotic mosquitoes, so that we can only act reactively. His message: “If you don’t know who your enemy is and what he can spread, you have to keep him out. Rigorous.”
The tiger mosquito landed in Genoa in 1990, and since then it has expanded its habitat quite a bit. They lay eggs in standing water, such as a flower pot, rain barrel, rain gutter or puddles along the road. It is recommended to stay alert and to report it immediately when seeing a tiger mosquito. What you can do to protect yourself from this mosquito, other than wearing covering clothing or sleeping under a mosquito net, is to avoid places where the mosquito has been found during the active period: from sunrise to sunset. You can also use mosquito repellants, such as Deet.
7 ways to prevent mosquito bites
But even in this case, large-scale international trade and climate change are the reason for the long-term settlement of this mosquito in Europe. In international trade, car tires are number one as the largest carrier of the exotic mosquito.
Some mosquitoes choose a more specific place to stay in Europe. For example, the yellow fever mosquito, which is found in Africa, South America, Asia and some parts of Australia, has only settled on the Portuguese island of Madeira and a region of northeastern Turkey. The physical complaints of the yellow fever virus that this mosquito brings are very different. From mild flu to high fever with bleeding. People traveling to South America should be cautious in the Amazon region. Here the mosquito is most active.
You can get vaccinated against yellow fever, but also always take all precautions such as suitable clothing, an impregnated net and anti-mosquito products.
The question, of course, arises what to do against all these mosquitoes? Because even the most “ordinary” mosquito, with which we started this story, can become the carrier of the West Nile virus throughout Europe due to climate change. Or the more exceptional cases: an Australian traveller who lost his memory after a mosquito bite in Bali.
It is certainly not the happiest news. But also not something we should panic about. Just as the world is changing, on a technological, climatological and social level, nature naturally moves with us. In that sense, for example, the Corona epidemic that we are currently living with also increases awareness of the vulnerability of humans. This is also a positive development, according to some giving in to the idea that maybe we are not always the strongest. It is the same with mosquito control. It is the opposite Calimero effect: I am big, and you are small, and that’s not fair. Sometimes the smallest wins.
In that sense, it is crucial to be adequately informed when you travel, also within your own country. Do not take any risks by going out uncovered at dusk, also keep a close eye when you are stung if you do not develop any complaints.
The predictions are that in the coming years there will be less and fewer climate differences between tropical and originally non-tropical areas. The difference between city and countryside is also changing. Larger concentrations of mosquitoes can also be found in the cities. They are also becoming increasingly resistant to all our repellent products.
Scientists argue that in the near future, government agencies should do more to map mosquito habitats and warn of the dangers. They are working on setting up a warning system and combing data about the occurrence of diseases with data about climate and socio-economic data. In this way, they hope to be able to anticipate the risks of outbreaks better.
It is interesting to realize that something as small as a mosquito can symbolize such significant issues in our world. Should we travel less? Shouldn’t we be more aware of global warming? Shouldn’t we already arm ourselves preventively instead of waiting for the damage to be done?
There is, of course, no single answer to these questions. Perhaps we can only say, let’s try to use our common sense together and protect ourselves and our loved ones as best we can at all times. Especially now.
Citation: Ministry of Transport, Public Works and Water Management, RIVM, Trouw, Wageningen University & Research, IRP, Care Plus, Telegraaf, NVWA, De Morgen, GreenMe.