THERE IS no doubt about it: mosquitoes are annoying. What is worse, their bites sometimes transmit serious diseases. Mosquitoes are vectors of many relevant human diseases like Malaria, as well as viral pathogens such as Dengue, Yellow Fever and the West Nile virus. Therefore, foreign mosquito species entering new countries not only produce ecological stress, but are also considered a potential threat to public health. This has been the case of many agricultural pests, which are unknowingly carried within plant shipments from one country to another, occasionally leading to their establishment in destination countries – challenging local economies, as well as natural systems.
As the world is becoming a smaller place, even mosquitoes travel by jet plane, carrying diseases that they spread in areas where they had formerly been unknown. And all this is done in a matter of hours … without having to pay for a ticket! Even more interesting is that some of them manage to happily move in and adapt to their “new home”.
The aggressive Tiger Mosquito, normally found in Asia, travels in other ways that are not so sophisticated. The “Tiger” manages to travel the world by laying its drought-resistant eggs in old tires, which are subsequently exported. In 1985, it slipped unnoticed into the US, inside a shipment of waterlogged used tyres from Asia. Within two years, these mosquitoes had established themselves in 17 States.
Tiger Mosquito is the nickname for Aedes Albopictus, a particularly vicious form of mosquito. Five millimetres long, black with white stripes, it lives where there is stagnant water. This mosquito differs from its cousin, the common mosquito, because it carries out its attacks by day instead of night. Its stings are extremely painful, and the Aedes Albopictus is capable of stinging someone through the clothes they are wearing.
Recently, it was in the news that an ethnological study revealed that this mosquito was set to invade the Valencian community in Spain this summer. It was detected in the Tarragona province two years ago and in Orihuela last October, and presents a threat that could spread across the entire community. It is not known for sure how it arrived, but, as Tiger Mosquitoes can only fly for 100 to 150 metres, it is possible that they travelled from Italy “comfortably sitting” inside used tires, with an ideal environment of decomposing vegetable waste and water.
According to Dr Ricardo Jimenez of the Valencia University Pest Control Unit, it seems unlikely that the Tiger Mosquito, if it invades the Valencian community, would be spreading the same illnesses that it can spread in its normal breeding areas of the Asian countries.
The Asian Tiger Mosquito has been identified as an insect that could potentially arrive in Portugal and the UK. If this were to happen, and if the mosquito becomes established, then it could cause a greater biting nuisance and may become involved in the transmission of disease.
Once more, let me make it very clear: one thing is the mosquito and another quite different thing is disease. As long as a Spanish mosquito does not become infected by a disease, it cannot pass it on to a human being. The infection zones of either Dengue or Yellow Fever are not currently anywhere near the Iberian Peninsula.
While your risk of getting diseases from mosquitoes is low, your risk of being annoyed by mosquitoes is high. In fact, mosquitoes may be so annoying, that you do not even enjoy spending time outdoors. Although common mosquitoes are most prevalent at dawn and dusk, it is not always possible or desirable to stay indoors during those periods, as they may be your favourite times for fun activities.
But, you can take steps to keep those pesky mosquitoes at bay, no matter what time of day it is. By taking some basic steps, you and your family may spend less time scratching itchy bites and more time at playgrounds or enjoying garden barbecues.
How to keep mosquitoes at bay
At least, one can always try! Insect repellents are one good way to keep mosquitoes at bay … possibly. When used properly, repellents are safe for children and adults alike. Keep in mind that repellents do not kill mosquitoes, so you may still see the pesky critters buzzing about. Repellents simply make you more difficult to find.
Check the labels of insect repellent products to see which chemicals or other ingredients they contain. And be sure to follow the product’s application guidelines. DEET has proven most effective.
What you wear can also help. Particularly in areas that are heavily infested with mosquitoes, wear socks, long-sleeved shirts, long trousers and light-colour clothing. Mosquitoes are more attracted to darker colours.
Mosquitoes need stagnant or standing water to breed. Eliminate standing water, especially after rain, and you can reduce the mosquito population around your home.
Other methods include electronic insect control systems, citronella-scented candles and replacing outdoor lights with yellow bug lights. These methods are also popular, but their effectiveness is unproven.
Why do some people get bitten and others do not?
What actually attracts mosquitoes? Research in the US concluded that genetics account for 85 per cent of the individual susceptibility to mosquito bites, but the concentration of certain acids on the skin can also help to attract the nasty little “vampires”.
Were you aware that female mosquitoes are the only ones that bite? They need the blood to develop fertile eggs. Males just hang around doing nothing.
If a mosquito finds you to be tasty, use hydrocortisone cream, calamine lotion or a baking soda paste to ease the discomfort of an itchy bite. A cold pack or bag filled with crushed ice may also help.
If the bite is not improving or changing for the worse after following these simple methods, or if more serious signs and symptoms appear, such as fever, severe headache, body aches, nausea, vomiting, swollen glands, a rash, lethargy, confusion or sensitivity to light, contact your doctor, do not wait. Prompt diagnosis and treatment are important.
The Malaria situation in Europe
Malaria is another mosquito borne disease, transmitted only by the female Anopheles mosquito. Until after the end of World War Two, Malaria was endemic throughout much of southern Europe. The Balkans, Italy, Greece and Portugal were particularly affected. Soon after the war, intensive control measures were initiated and, by 1970, Malaria transmission had been virtually eradicated from the continent, a considerable achievement which contributed to the economic development of some of the worst affected areas in southeast Europe. In 1975, the World Health Organisation (WHO) declared that Malaria had been eradicated from Europe.
In the Algarve, the risk of contracting diseases carried by mosquitoes, such as Malaria and the now in-vogue West Nile virus, is extremely low. This is still a privileged tiny corner of the world, for several reasons!
Old tires, lucky bamboos
Tiger Mosquitoes were found to routinely travel in comfort, via egg infested shipments of used tires, but it was also discovered that they have more “romantic” ways of moving around.
The trade in lucky bamboo has increased recently, because it has gained worldwide attention as a popular gift. Shipments of this plant from China, on inspection by quarantine officers when arriving at Los Angeles, US, were found to contain Aedes Albopictus. Several live adult mosquitoes escaped as the containers were opened, due to the fact that Aedes Albopictus larvae had been transported within dracaena plants, shipped in standing water. The US authorities dictated an embargo on this type of shipment, favouring dry airfreight.
So far, there are no “Tigers” in Portugal, mosquitoes I mean … so for now, we can only do our best to avoid turning into a feast for the not so exciting common mosquitoes. We can only hope that the other ones will choose another place to live, whenever they decide to widen their horizons and move from their home countries into a new environment.
Who said that only man could do it? Travelling I mean ….
Best health wishes,
Dr. Maria Alice
Consultant in General and Family Medicine
Director – Luzdoc International Medical Service Tel. 917 811 988