A highly invasive tropical species

The least we can say about Belgium is that it certainly isn’t tropical! The last factor - a favourable environment - should therefore protect us against the emergence of tropical diseases such as dengue fever or chikungunya.  Furthermore, the ITM researchers seem to doubt that the colony of tiger mosquitoes observed this summer close to Antwerp would be able to survive the winter. Furthermore, the number of people who carry these viruses is very low in Belgium. It is therefore highly unlikely that one of these mosquitoes will come across someone contaminated by dengue fever or chikungunya, bite them and then transmit the virus to another healthy person. In Belgium, the risk of “autochthonous” transmission, as the scientists say, is almost zero.

For the moment... Because geographically, it appears that the risk is advancing. The vector, in any case, is spreading rapidly: leaving South-East Asia around the 1980s, the tiger mosquito invaded the five continents in 20 years: USA (1985), South Africa (1989), Italy (1990), New Zealand (1999), France (1999), Belgium (2000), Spain (2004), Germany (2007)… Before 1970, according to the WHO, only nine countries had had an epidemic of dengue fever. There are currently more than 100! Forty percent of the world’s population is now exposed to the risk. And Europe is no longer safe from an outbreak of dengue fever, the WHO believes. The first cases of “autochthonous" transmission of dengue fever were recorded in France in 2010. A first outbreak of chikungunya struck north-east Italy in 2007.

Faced with the clear increase in risk, the researchers from Gembloux Agro-Bio Tech recommend a long-term monitoring plan at the sites identified as import sites, especially tyre depots or companies that import bamboo. And treatment with biopesticides when the colonies are detected. “But this won’t be enough”, Slimane Boukraa believes. “We may also have to envisage the disinfection of the means of transport by which the incriminated goods – tyres and bamboo - were conveyed. A collective response to the problem must also be developed. Every one of us can take action in an effort to contain the invasion. How? By getting rid of unnecessary stagnant water reservoirs, which provide a site for the invasive mosquitoes to lay their eggs: the small wheelbarrow in the garden, an old flowerpot, a plastic toy, etc." According to the researcher, a special effort should also be made on farms as regards cattle troughs or by covering used tyres used for silage heaps.

But Slimane Boukraa is certain of one thing: we haven't heard the last of the tiger mosquito...