The very surprising truth about who really gets eaten alive by insects – as doctors reveal the ultimate guide to preventing bites and stings

Every summer, Anne Larchy knows she will need to make an emergency trip to an urgent care clinic at least once.

Throughout her adult life, Anne, 52 from north London, has had an extreme reaction to insect bites. Her feet and hands swell to nearly double their usual size and the bites often become infected – requiring treatment with antihistamine tablets (the body releases histamine in response to a bite or sting, causing swelling and itching) as well as antibiotics.

Anne Larchy, from north London, suffers extreme reactions to insect bites and stings

Once, on a trip to Israel 25 years ago, she had to be admitted to hospital overnight after 15 bites became infected – and she needed intravenous antihistamines.

On another occasion, she was bitten on her eyelid, leaving her eye painful and so swollen that she couldn’t open it for four days. She missed out on being a volunteer for the London 2012 Olympics because a bite on her foot meant she couldn’t put her shoe on, let alone stand because of the swelling and pain.

‘Each summer I get an infected bite at least once, often on my foot, ankle, hand or arms probably as they are the most exposed,’ says Anne, who is a health coach.

‘I usually get bitten at the park or golf course,’ says keen golfer Anne. ‘I apply strong insect repellent to try to stop it from happening and my arms and legs are fully covered, but they still manage to bite me. I know it could be worse if I didn’t do that, though.

Why do some people such as Anne react to bites in this way? Blame the individual’s immune system – and how often they are bitten: you tend to react more if you’re not bitten much, explains James Logan, a professor of medical entomology at the London School of Hygiene and Tropical Medicine.

‘Over time, your body can become immune and not react very much,’ he explains.

Some of us do get bitten more than others, which could be down to our smell, he adds. ‘People who don’t get bitten much produce natural repellents in their body odour which act as their own natural defence system.’

These chemicals (known as aldehydes and ketones), are thought to be be down to genetic and environmental factors, as well as to the types of bacteria that we all have living harmlessly on our skin.

‘Some of these chemicals are released in sweat and they can also be eaten by the bacteria on the skin which, in turn, produces more of these chemicals – in theory making bites even less likely,’ explains Professor Logan.

Body size can also be a factor in whether you are likely to be bitten. A study led by Professor Logan, published in the journal BMC Public Health in 2010, found that midges were more likely to bite men who were tall and women with a larger body mass index (BMI).

Anne’s extreme reaction to bites can cause her hands to swell to nearly double their size

‘We don’t really know why it is. It may be because there is more of them to bite, or their bodies are producing more attractants, such as carbon dioxide, in their breath,’ he explains, adding that the gas is a strong signal to insects that an animal or human is nearby. It is thought that taller people have larger chests and lungs, meaning they may take in more oxygen and breathe out more carbon dioxide.

Research also suggests that people with blood type O are most attractive to mosquitoes. In research, published in the American Journal of Entomology in 2019, mosquitoes were given the option to feed on A, B, AB and O blood types and they chose type O more frequently. It is thought they ‘sniff out’ O blood type, though how and why is not clear.

In fact, this keen sense of smell could be harnessed to diagnose different conditions in future. Professor Logan is using insects as sensors in his lab to work out the smell of different diseases. ‘Insects live in a hidden world of odour which is like a hidden world of communication,’ he explains. ‘We’re building machines – basically sniffer robots – to do the job of an insect by detecting if someone has malaria, and the hope is that one day this could detect other conditions, including cancer.’

For most of us, the painful, itchy, swollen areas which develop around the bite or sting usually resolve after a few days and can be managed at home with antihistamines and soothing creams. The swelling – a sign of inflammation – occurs as part of the immune response as our body releases histamine and other chemicals to seal the area and respond to any harmful substances that have broken through the skin.

However, there is a risk that bites and stings become infected. Signs include the area becoming hot, red, painful and producing pus. People with poorly controlled diabetes are at particular risk of infected insect bites and stings because of their high blood sugar levels. ‘Bacteria like feeding on sugar, so when someone with diabetes has a cut or bite they need to keep a close eye on it because infections can develop more quickly,’ advises Brendon Jiang, a pharmacist based in Oxfordshire and vice chairman of the Royal Pharmaceutical Society’s English Pharmacy Board. (The condition also affects the immune system, making it harder to fight off infections.)

If the raised, red lump doesn’t start to go down after a couple of days, draw around the area and see if it spreads, suggests Professor Logan. If the infection spreads, you may need to see a doctor and you may need antibiotics. A study published last year in BMJ Open found that two thirds of people who sought help for insect bites from out-of-hours primary care in Birmingham between July 2013 and February 2020 were prescribed antibiotics.

But Dr Sam Finnikin, a GP based in Birmingham, who led the research, says insect bites often don’t require antibiotics, and this is especially concerning in light of antibiotic resistance.

‘Clinicians find it difficult to decide which insect bites would benefit from antibiotics,’ says Dr Finnikin, who is also a researcher focused on clinical decision making at the University of Birmingham. ‘We know the vast majority improve without antibiotics, but some infected bites may get better slightly quicker with them. Usually, the immune system can deal with infections unless there are concerns about sepsis.’ Any infection, including a bite, can potentially develop into this life-threatening condition where the immune system overreacts and damages the body’s own tissues and organs.

However, he adds: ‘It’s important that antibiotics aren’t given if there’s no infection as they won’t have any benefit and can cause side-effects such as thrush and diarrhoea.’ Sometimes people are given antibiotics for an insect bite once, then they mistakenly feel they need them every time, he says,

Anne Larchy’s reactions are due to an allergy to the venom in bites and stings, which can cause much nastier symptoms as the body overreacts, explains Jiang.

A serious allergic reaction – anaphylaxis – can cause swelling of the airways or around the mouth and face, dizziness, sweating, difficulties breathing and a drop in blood pressure. ‘If you experience any of these signs then call an ambulance,’ says Professor Logan. ‘Usually it happens immediately but, in rarer cases, it could come on a couple of hours later. If people have known serious allergic reactions, they should carry an EpiPen.’

SO WHICH ARE THE NASTIEST BITES OR STINGS?

The severity of the bite or sting often depends on the culprit.

Horseflies can give a nasty bite due to their ‘saw-like’ mouths, says Professor Logan. They can be found around animal dung, meaning they can transmit bacteria into the wound, causing an infection. ‘There aren’t that many insects which have mouth parts able to penetrate our skin, so most flies and spiders won’t bite us,’ he adds.

Wasps and bees inject venom into the skin from a stinger at the tail end of their bodies, and wasps are generally more harmful. A study published in the journal International Microbiology last year compared microbes carried by honeybees with wasps and hornets living on a Greek island. It found that wasps and hornets were more likely to carry harmful bacteria which could potentially lead to an infection. This is thought to be due to contact with faeces.

‘In general, bees are quite docile and would only sting when they’re threatened. After they have stung, they die. This is because the bee cannot remove the stinger from the person they have stung without it rupturing their abdomen. Wasps are more aggressive and can sting multiple times and in groups, so it can feel worse and last longer,’ says Brendon Jiang. Even ants can bite us, but the types of ants in the UK are not generally an issue and their bites are usually minor, he adds.

As the UK’s climate changes, with longer summers and warmer winters, the chance of insects typically seen in more exotic countries coming here is increasing. In the UK, there have been more than 120 sightings of Asian hornets in total since 2016, most of which were spotted this year and last year. Aside from a few cases, they were all recorded in the south of England. These insects have caused deadly stings in other countries and there are increasing concerns they may become established here as the climate becomes more hospitable for them, says Natalie Bungay, from the British Pest Control Association. And it’s a matter of time before Asian tiger mosquitoes and Aedes aegypti mosquitoes – originally from tropical regions but now found throughout southern Europe – become established here, says Professor Logan. They transmit diseases, including Dengue fever, yellow fever and Zika. ‘It’s already warm enough for them to survive in the UK for some months of the year,’ he says. In fact, both species of mosquitoes have already been found in the UK but there is no evidence yet that they have become established here.

‘Mosquitoes, midges, flies, wasps and hornets need a temperature of at least 13C to lay eggs which is usually spring to late autumn,’ says Natalie Bungay. ‘Rainfall followed by a sunny day creates perfect conditions for mosquitoes and midges to breed.’ We are seeing insects and ticks (which can carry Lyme disease) surviving for longer in the current climate, adds Professor Logan.

Ticks are increasingly a problem in the UK, in woodlands and grasslands, including in holiday spots such as Cornwall, Suffolk, Norfolk and Scotland. These can carry the bacteria that causes Lyme Disease, which affects 1,000 people in the UK each year. In some cases, people suffer longer-term problems such as pain and swelling in joints, and problems with concentration and memory.

How to treat bites and prevent them in the first place

GP Dr Finnikin recommends keeping a supply of over-the-counter antihistamine tablets and creams, and hydrocortisone cream which contains a mild steroid and can relieve itching. Scratching the affected area can increase the chance of infection because it can make the break in the skin worse and introduce bacteria from fingernails into the wound.

‘There’s a scratch-itch cycle. When we scratch, it causes more histamine to be released and the chemical then triggers more itching,’ explains Dr Finnikin. Massaging or rubbing the area is better and cooling gels can soothe the skin. Look for products containing ammonia, which neutralise some of the venom from a bite or sting, because venom is usually acidic while ammonia is alkaline. Pharmacist Brendon Jiang recommends using cold compresses to reduce swelling and says bite relief pens, which deliver small electric shocks to the affected area, can be beneficial. This distracts nerve cells from sending itch signals to the brain, relieving itchiness.

Antihistamine creams can relieve itching and a cold compress can help to reduce swelling

Where possible, remove the sting with tweezers or fingers, and use a twisting method to get ticks off the body, he adds.

To avoid bites and stings, Professor Logan recommends insect repellents containing DEET, IR3535, oil of lemon eucalyptus (OLE) or Picaridin. ‘These work well on mosquitoes, midges and ticks,’ he says, adding that it’s best to avoid going out at dusk, when most mosquitoes are out. And avoid walking through long grass (where ticks are often found) and cover up with long trousers, long socks and long-sleeved tops.

***
Read more at DailyMail.co.uk