I have recently come back from a holiday in the Mediterranean, a well-known mosquito hot spot. On the last night of my holiday, having diligently applied DEET throughout the week I completely forgot to spray it on. As a (very painful) result I ended up with 25 bites, and yet the person who slept no more than a foot away from me escaped scot-free. This got me thinking, is there something specific to each person that makes them more or less tasty to these blood sucking parasites?
Now I’m home and I’ve done a little research into the subject it seems there is no universal answer to this question. Just many scientists each with their own theory valiantly testing and hypothesising in order to one day develop a fool proof repellent.
It has been well known for years that mosquitos are attracted by the CO2 we all breathe out and apparently they can “smell” us from up to 50km away. However, everyone breathes so this can’t be the reason why some are bitten more than others, except when it comes to pregnant women who exhale 21% more CO2 than their non-pregnant friends. So what else attracts mosquitos? The second most common answer to this is body heat, and there might be something to this hypothesis also proved by pregnant ladies. When carrying a baby the woman’s stomach will be much warmer than the rest of the body due to the amniotic fluid inside, this increase in temperature has been shown to attract mosquitoes to the woman and increase the number of bites.
One hypothesis that has since been debunked was that it is your sweat that attracts them, this theory might have been born out of the heat theory – warmer people attract mosquitoes, warm people sweat more, ergo sweat attracts mosquitoes. However, we now know this not to be true but there is a theory that some emissions from the skin do make a person more or less attractive.
The latest research has hypothesised that some people give off a “masking smell” that repels the mosquitoes by hiding the actual smell of their body. However the basis of this unattractive scent is still being researched. Some scientists believe it to be potassium in the blood which creates the natural repellent and so advocate eating lots of bananas, whereas others think it is the skin’s pH making bacteria on the skin emit specific chemicals. Whatever the cause of this masking there is a more pressing reason to finish this research than to reduce the cases of mild discomfort and ugly ankles in people like me. Across the world between 350-500 million people are infected and 1 million are killed each year and so by figuring out what keeps some people safe scientists hope to develop a repellent as new method of preventing malaria.