Aedes albopictus, commonly known as the Asian tiger mosquito has recently been identified in the Algarve, and is a potential carrier of various extremely unpleasant diseases. Image: Pixabay

Risks of dengue, zika and chikungunya in summer

World Health Organisation warns of need to control mosquitoes

Portugal is one of the southern European countries placed on alert for risks of dengue, zika and chikungunya in the context of global warming – all of them potentially deadly diseases.

In Mértola in January mosquito eggs with the potential to transmit these illnesses were found, recalls Correio da Manhã – interviewing university professor on infectiology and tropical diseases Jaime Nina on the probability of outbreaks as temperatures start to soar.

Dr Nina explains that there is a “common negligence throughout southern Europe over the eradication of mosquitoes”.

For example, outbreaks of malaria in the past (long before global warming became an issue) were controlled by releasing Gambusia fish, which eat mosquito larvae, into dams and reservoirs.

Petrol can also be used to reduce mosquito populations, he said.

But efforts in most places are reactive, rather than preventative.

Dr Nina referred to the outbreak of dengue in Madeira in 2012 which affected 2,000 people. “The mosquito was never eradicated”, he told CM.

Now, the World Health Organisation (WHO) has renewed its perennial warnings, citing “isolated cases” identified in Italy.

Says Raman Velayudhan, WHO chief for the control of tropical diseases: “one of the greatest challenges in the control of mosquitoes is that eggs can stay dry for months while they travel in containers, hatching in a new country after a few hours after coming into contact with water. Then comes the mosquito”, which becomes most active once temperatures go above 17ºC.

The principal symptoms of dengue, zika and chikungunya are high fevers, intense pain in the joints of feet and hands, tiredness and lack of appetite. (If caught in time, these diseases can be treated, but in the case of zika, they can have devastating effects on children developing in the womb.)

Meantime, a pioneering project involving the Ricardo Jorge public health institute and ARS Algarve (regional health authority) has been working on eliminating the mosquito (Aedes albopictus) that transmits these tropical diseases.

Aedes albopictus is an invasive species most associated with outbreaks of dengue, zika and chikungunya. Examples have already been identified in various parts of the Algarve (namely Loulé, Faro/ Gambelas and Tavira).

Reports late last year explained that mosquitoes that had been ‘sterilised’ by radiation in a labratory factory in Italy were being sent to Portugal by plane as part of a pilot study which consisted of releasing non-biting beneficial mosquitoes (sterile males) which, when mated with females, “prevent new generations”.

The idea of the project was to see if this form of biological control suppresses the natural population of mosquitoes, and thus reduces the risks of outbreaks of diseases.

Since the initial stories on the project, howeverm, very little by way of new information appears to have been released.

An advice pamphlet on how to keep homes ‘safe’ from mosquitoes can be found here

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