Difficult to win fight against invasive mosquitoes – specialist

But having them here not synonymous with disease

Fears of mosquito-borne diseases powered by global warming have seen the World Health Organisation renew warnings about the need to control these insects. But the coordinator of the national network for vector surveillance (REVIVE) says this is much easier said than done.

Speaking to Lusa as the country is assailed by blistering temperatures, Maria João Alves admits: “It is likely that the war will not be won, because this mosquito (Aedes albopictus) is really invasive. What we want is to keep the number of specimens as low as possible so that there is no possibility of transmission of infectious agents”.

As she stressed, being bitten by a mosquito does not mean one contracts any of the diseases (dengue, zika, chikungunya) that this species carries.

The spread north from Africa of the Aedes albopictus is a European problem – not just one affecting the Iberian Peninsula.

Commonly known as the Asian tiger mosquito, this invasive species is among the 100 worst in the world, in as much as its spread appears relentless.

A researcher at the department of infectious diseases of the national health instutute Dr Ricardo Jorge (INSA), Maria João Alves explains that “the whole of Europe is fertile ground” given the “ideal conditions” for the mosquito to hatch.

“For now, we are still in a very early stage of occupation”, she explains.

Having this mosquito among us is not synonymous with disease – and to date there has been no specimen of the species collected on the mainland that was contaminated.

For this to happen, “infected people have to come from areas with dengue, for example, then, during the period in which they have the virus circulating in their blood (five days), they come into contact with other mosquitoes and it is these that transmit it to people”.

“If we continue to act as we have been acting we will reduce the probability of autochthonous transmission to a minimum“, she says. No one can say there is zero risk, but there is no reason for any kind of panic.

On this score, Maria João Alves gives the example of France, where the Asian tiger mosquito was first detected in 1999, but the first autochthonous cases of dengue only happened in 2010. 

In Europe there have already been 144 cases of autochthonous dengue fever, 65 were in France last year.

“It takes a few years and it is in those years that we should act, in which we should reduce the population of mosquitoes, inform the public,” she explains.

To this end there is constant monitoring, and research.

When ‘Aedes albopictus’ appeared in Mértola (eggs only) last year, “the Alentejo already had, in a collaboration with municipal councils, traps in place for a long time, waiting to detect the first introduction”, she said.

In total, more than 300 environmental health technicians are involved in REVIVE’s collections.

Source material: LUSA