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Do mosquitoes bite some people more than others? Maybe you're the type of person who's constantly
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itching when you're outside at night. Or you're the type that get hassled at all.
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According to the experts, mosquitoes are picky about who they bite. But do we know why?
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There's more than 300 species of mosquito in Australia, but only 20 pose a risk to human
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health through disease or nuisance biting. You may also be surprised to learn it's only
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female mosquitoes that bite and that's because they need an energy hit to develop their eggs.
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But how does she do this? When she has found an animal or a person to
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bite, she'll land on the skin and she'll start probing away at the skin with her proboscis
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and the proboscis isn't a sharp, needle-like device, it's actually a little bit flexible.
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So she can inject that into the skin, move around and find a source of that blood.
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But also, the feeding tubes in the proboscis, some of them spit and some of them suck.
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So the mosquito will inject some saliva into the skin - it has anti-coagulants, a little
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bit of anaesthetic, it helps the blood feeding go through much easier, and then in other
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tubes, the mosquito will suck up the blood.
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So how does a female mosquito choose her next meal?
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Researchers say she's initially attracted by the carbon dioxide we breathe out.
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Then, when the mosquito gets closer, they respond to the heat of our body - the higher
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your body temperature, the more likely you are to get bitten.
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Scientists think the key attractor is the chemical of our skin produced by bacteria
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and sweat, which signals how attractive, or not, we might be.
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But, it's very difficult to tell exactly what bacteria or smells are appealing, and every
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species of mosquito is slightly different in what it finds attractive.
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There's also other factors that come into play, like the colour of our clothing.
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Dark colours tend to attract mosquitoes more than light colours - perhaps they can see us moving
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around more in dark clothing. Scientists also recently discovered a gene
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in mosquitoes that leads them to bite some people over others, but they're yet to determine why.
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And there's a load of other theories out there,
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like eating garlic, or taking vitamin B will change how attractive we are to mosquitoes.
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But science has failed, so far, to show any evidence this works.
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We do know that some research shows that maybe diet has a subtle change to our attractiveness.
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We know from studies in Africa that drinking beer may make us more attractive to mosquitoes
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that spread malaria parasites. But it doesn't mean that avoiding drinking alcohol will prevent
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you from being bitten by any mosquitoes.
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Your blood type may also have an impact, though
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scientists think not as much as the smell of your skin. Studies in Africa investigating
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malaria transmission are examining whether type O blood attracts a few more mosquitoes
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than other types. But just because you don't itch, doesn't mean
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you weren't bitten at all. Everyone differs when it comes to their reaction to mosquitoes'
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saliva, just like we do with certain foods. But putting up with nuisance biting isn't
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the only worry when it comes to mosquitoes.
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They can also carry disease, with the World
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Health Organisation estimating there are more than 700,000 deaths every year from vector-borne
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disease. Mosquitoes are carriers, along with others including ticks, sand flies and fleas.
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It's for this reason that mosquitoes are considered the deadliest animals on the planet.
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Malaria is perhaps the best-known of these diseases and causes more than 400,000 deaths
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every year. Australia was declared free of malaria in 1981.
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The disease we're most worried about in Australia is caused by Ross River Virus. We get thousands
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of cases of human disease across Australia every year. It doesn't matter whether you're
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in Cairns, or Hobart or Sydney, or Perth, there's a chance that in some of those areas
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during some seasons you may be exposed to that virus. It's much more prevalent outside
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metropolitan areas and the reason for that is that the mosquitoes don't hatch out of
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the wetland infected with the virus. They have to bite an animal first, and typically
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that's a kangaroo or a wallaby. So it's in these rural, or semi-rural areas where the
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risk is much greater of mosquito-borne disease in Australia.
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Ross River Virus has no treatment or cure so the best way to prevent the illness is
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to stop mosquito bites. And there's plenty of ways you can do this.
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Wearing long sleeves and long pants to minimise access to skin is one of them.
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Using repellents, like sprays or lotions is another. Products containing DEET or picaridin or extract
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of lemon eucalyptus are most effective. The higher the concentration, the longer it will
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last on your skin and the less you will need to re-apply.
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Burn mosquito coils and candles containing insecticides in outdoor areas. They'll help
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protect you if you're within a few metres. Sitting under fans can also be useful as mosquitoes
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can't fly easily in windy conditions. Other measures, like sound-emitting devices
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and wristbands exist, but there's no evidence yet showing they work.
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Wearing a colourful band on your wrist, no matter how strongly it smells, it won't provide
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protection for the rest of your body.
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Cleaning up around the home is another important
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way of lowering mosquito numbers. They love breeding in pet water bowls or bird baths
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so change the water regularly, and check for common places water collects like pot plant
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drip trays, blocked gutters, toys, or old tyres.