A woman from Steenokkerzeel became seriously ill a few weeks ago after she was bitten by a malarial mosquito. The mosquito had probably entered Belgium via Zaventem airport. Such cases of "airport malaria" are rare, but they have become more common in recent years.
There are more than 3,000 species of mosquitoes worldwide. Only a few of them can transmit malaria. It concerns mosquitoes belonging to the genus Anopheles.
You can only get malaria if you are stung by an Anopheles mosquito that is also a carrier of a specific parasite. This parasite then multiplies in your body, first in your liver and then also in your red blood cells. This causes high fever, muscle aches, headaches and chills. Patients sometimes experience it as a "flu-like feeling," although the fever can be very high.
Untreated malaria can be fatal. In 2020, according to the World Health Organisation, more than 600,000 people died from the effects of malaria.
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So, can someone get malaria if they do are not coming back from a tropical destination? It is possible, although the chance is very small. Mosquitoes sometimes travel on a plane that comes from a tropical destination. It can then bite someone near the airport.
Most of these mosquitoes are not carriers of the parasite that causes malaria, and they are therefore harmless. Only in rare cases is a mosquito a carrier.
If such an Anopheles mosquito bites you, you can become infected and therefore get malaria. In that case, one speaks of "airport malaria," because the contamination usually occurs near an airport. Some exotic mosquitoes, for example, the tiger mosquito, also appear in tire centres.
Anopheles is a genus of mosquito with over 460 species, first described and named by J. W. Meigen in 1818. Photo credit: Wikimedia Commons.
"That's because there is a lot of international transport of tires," says Professor Leen Delang of KU Leuven. "Sometimes a thin layer of water remains in those tires. Mosquitoes can lay their eggs in it and those eggs can then become adult mosquitoes."
Airport malaria is very exceptional, but there have been several cases in Belgium in recent years. For example, an employee of the airport was infected last year. A couple from Kampenhout was even killed by malaria two years ago. They were probably stung by a lone, stray mosquito.
"We have thoroughly investigated that case," says biologist Isra Deblauwe of the Institute of Tropical Medicine. "Probably the mosquito came from Gabon or Cameroon, although we can't say for sure."
Airport malaria is not new, but it seems to be more common in recent years. This is mainly due to the sharp increase in international air traffic. As a result, there are more planes flying back and forth between tropical destinations and
countries without malaria, such as Belgium. That increases the chance that occasionally some mosquitoes travel with you.
This map shows an approximation of the parts of the world where malaria transmission occurs. Credit: Centers for Disease Control and Prevention
Global warming also plays a role. "As a result, there are more frequent heat waves," says Deblauwe. "Tropical malaria mosquitoes that travel by plane to Belgium can then survive longer. As a result, they can also fly further and there is more chance that they will bite and infect someone."
Exotic Anopheles mosquitoes that can transmit malaria do not occur here. So, they first have to survive the long plane journey to Belgium. Upon arrival, they are immediately confronted with the next challenge: the temperate Belgian climate. After all, malaria mosquitoes thrive best at warm temperatures and high humidity.
"You don't find their typical breeding grounds in Belgium very much either," says Deblauwe. "The chance that exotic malaria mosquitoes can settle in Belgium is therefore currently non-existent."
"We advise GPs (general practitioners) in the vicinity of the airport to be vigilant," says Joris Moonens of the Agency for Care and Health. "They have to take malaria into account as a possible diagnosis. This is important when they get people with symptoms such as muscle pain and fever, without a clear cause."
In Belgium, there is also the MEMO+ project for the monitoring of exotic mosquitoes.
"We set mosquito traps in car parks, mainly looking for tiger mosquitoes," says Deblauwe. "Sciensano also has a website where citizens can post photos of tiger mosquitoes. But tiger mosquitoes cannot transmit malaria parasites, but they can transmit some viruses."
In the aviation sector, too, they pay attention to the problem. Aero-Sense, a company from Roeselare, develops chemical products for use in aircraft.
"The cargo area is thus treated before take-off," says Robbe Vangheluwe of Aero-Sense. "The cabin crew also goes down the aisle with a spray can. This way you can prevent mosquitoes from travelling with you."
The Aero Sense insecticide is sprayed in the cabin of the aeroplane after every flight to ward off mosquitos or other pests. Photo credit: Aero Sense
Such treatment is mandatory in many countries.
"At Zaventem airport, they only release an aircraft if it has been handled correctly," says Vangheluwe. "The airline even has to hand over the empty spray can when landing, so that everything can be checked."
With all these measures and thorough monitoring, the danger is currently very small even if you live near the airport.
