EVERYONE loves a summer holiday, but it can also throw up some challenges for our skin. Mosquito bites can be really frustrating both home and abroad.

According to consultant dermatologist and British Skin Foundation spokesperson Dr Anjali Mahto, an estimated 10-20 per cent of people are highly attractive to mosquitoes and consistently get bitten more often than their counterparts.

While genetics are thought to count for up to 85 per cent of our susceptibility to insect bites, scientists have a number of ideas about why some of us are more prone to being ravaged by mosquitoes than others.

She says: “Research suggests that certain blood types are more attractive to mosquitoes than others. A large number of the population secrete saccharides or sugars through the skin dependant on their blood type that mosquitoes are able to sense.

“Studies as early as 1972, suggest that mosquitoes seem to prefer those with Type O blood. Mosquitoes land on skin with Type O blood nearly twice as often as those with Type A. People with Type B blood fall somewhere in between this range.”

Mosquitoes are attracted to exhaled carbon dioxide via receptors in an organ known as the maxillary pulp and can detect their prey from up to 50 metres away. Consequently, those exhaling more gas i.e. often larger people with increased body size, are more likely to get bitten.

“Aside from carbon dioxide, mosquitoes also rely on other substances, often at close range, to home in on their targets. These include chemical and compounds secreted in skin and sweat, including lactic acid, uric acid, ammonia, steroids, and cholesterol to name a few.

“Strenuous exercise can result in a build-up of lactic acid which may make individuals more susceptible. Genetic factors are likely be involved in the composition of these substances that are naturally secreted by our bodies,” said Dr Mahto.

Large numbers of bacterial species naturally inhabit human skin and researchers have shown that certain bacterial subtypes present in large numbers e.g. staphylococcus epidermidis, make individuals more attractive to mosquitoes.

Others e.g. pseudomonas aeruginosa, appear to have the opposite effect. It also seems that having a wide diversity of bacterial types living on the skin make it less attractive.

Pregnant women are more susceptible to bites than their non-pregnant counterparts. This is, however, likely to be due to the fact that they exhale relatively more carbon dioxide and have a higher resting body temperature.

Dr Mahto suggests mosquitoes are attracted to dark colours such as black and navy blue, as they use vision along with scent to locate their targets. It is best to dress in light colours such as white or pastels to reduce the risk of this.

She says the most effective way to reduce the risk of mosquito bites or insect bites in general is to use either diethyltouamide insect repellent. Research shows a repellent containing approximately 20 per cent DEET will protect the wearer for about five hours. It has a good safety record and weaker formulations of 10 per cent or less are safe to use on infants from the age of two months.

There are a number of plant based chemicals that can offer some protection against mosquito bites. They are not as effective as DEET and are not recommended as the only protection in areas that are endemic to malaria. These include citronella, lemon eucalyptus, and neem to name a few.

Insect bites can commonly cause lumps (papules), itching (pruritus), and whealing (urticarial) of the skin. Occasionally, small blisters (bullae) may develop. There are a number of things that can be done to minimise discomfort.

• Antihistamines – taking oral antihistamines will relieve the itch and swelling e.g. cetirizine 10mg once or twice a day.

• Mild steroid cream – hydrocortisone 0.5-2.5 per cent applied twice daily for a few days can reduce inflammation and itching

• Calamine lotion to affected areas

• Cooling the skin e.g. with a cold compress

The bites should usually settle within a few hours to a few days. It is important to avoid scratching the skin as this increases vulnerability to developing infection at the site of the bite. One of the many functions of skin is to act as a barrier to the outside world. If the skin becomes broken e.g. as a result of scratching, infection is much more likely to develop.

If you notice pus or discharge in or around the bite, increased pain, redness or swelling, or swollen glands, then suspect infection. This may require treatment with oral antibiotics (usually flucloxacillin unless there is an allergy to penicillin) so attend your local doctor.