An unwelcome traveller

By Lauren Hoskin

Originally from South East Asia, the Asian Tiger Mosquito (Aedes albopictus) began its migration towards Europe over 30 years ago with the rise of globalisation and the international goods trade. Like all competent travellers, the mosquito is adaptable to different climates and is unperturbed by less-than-perfect living standards. With this in mind, it packed its jowls full of human blood, found itself a comfortable seat in a used tyre, and began the long journey across the globe towards a new life. The only issue being that the Asian Tiger Mosquito was rather unwelcome in these parts of the world, just as it is unwelcome in Asia.

These black and white striped mosquitoes not only cause itchy and painful bites, but unfortunately for us also have the power to transmit a number of viral diseases, such as dengue fever, Chikungunya fever and yellow fever. When female mosquitoes bite infected humans, the virus is drawn up along with the blood into the mosquito’s digestive system. Here it infects the epithelial cells lining its gut for about eight days before being spread throughout body and eventually reaching its salivary glands. In order for a mosquito to obtain enough blood when it bites, it must overcome haemostasis- the thickening of blood. To do so, it inserts saliva to open up our blood vessels, stop the clotting of platelets and red blood cells, and also annoyingly cause itching. Hence, when the little vampire bites its next victim, the virus is injected along with its saliva. Mosquitoes remain infected but unaffected for life, spreading viruses as they please.

For some diseases that it may bring, such as dengue fever, there is no current vaccine. Because dengue is caused by four possible types of Dengue Virus, a vaccine must be effective against all four types to be useful.  Scientists are currently working on a suitable vaccine which is estimated to be ready by 2014. Other such diseases such as Chikungunya fever have already affected nearby countries, with a large outbreak in Italy in 2007 and two reported cases in France in 2010. The mosquito first reportedly entered Europe in 1979 when it arrived in Albania. Since then it has spread through 14 European countries and shows no sign of stopping. Scientists fear that climate change is making conditions in the UK far more comfortable for this species, and it is only a matter of years before is crosses the channel into our fair land…

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