The researchers from ULg informed their colleagues at the Institute of Tropical Medicine (ITM) in Antwerp of their discovery. ITM is in charge of a programme to monitor exotic mosquitoes. Between last August and October, ITM researchers discovered several more dozens of tiger mosquitoes (adult and larvae) in the close surroundings of the tyre plant. And that’s not all: end November, a live larvae was found in the port of Antwerp in a cargo of bamboo shoots from China. Thus revealing a second method of entry into our country. Bamboo and tree holes are the natural tropical home of the tiger mosquito in South-East Asia. Large international ports, such as Antwerp, are obviously the ideal port of entry for invasive tropical species.

An invasion to worry about?

But should we be afraid of the tiger mosquito? Here in Europe, mosquitoes are, at most, accused of spoiling our pleasant summer nights with their mocking attacks, resulting in an exasperating itchiness in the early hours. Not the end of the world. But in tropical countries, some mosquitoes can transmit serious diseases. The tiger mosquito is a vector for dengue fever, chikungunya (see below) and even yellow fever. For the time being, scientists don’t want to cause panic. “There’s no reason for public health concerns at the moment", the researchers at ITM confirmed in a recent memo. “The risk of the imported tiger mosquitoes carrying viruses such as dengue fever or chikungunya is very low”. Furthermore, it is uncertain whether the current small colony will be able to survive the winter. The larvae of this tropical species have trouble withstanding the cold. But there is indeed a risk in the longer term because the intensification of international trade increases the probability of tropical species entering Europe and global warming favours their presence.

For a tropical disease to emerge (or re-emerge) in our latitudes, four factors would have to be present.

1.    A pathogen, i.e. an infectious parasite. For instance, dengue fever is caused by a virus. Symptoms appear several days after infection; they can range from a mild fever to a high fever accompanied by headaches and sharp muscular and articular pain. Dengue hemorrhagic fever (abdominal pains, vomiting, haemorrhaging) is a sometimes fatal complication of the disease. The disease is especially rife in Asia and Latin America. There is no specific treatment for dengue fever. Chikungunya, also caused by a virus, has comparable symptoms:  high fever and articular pain. In the majority of cases, the symptoms disappear after several days or weeks. Sometimes, although more rarely, the articular pains may persist for months or even years. There is no treatment. This disease in endemic in Africa, Asia and in the Indian sub-continent.