You're more likely to be bitten by a spider while you're abroad, if you keep non-native spiders as pets, or if you have a job that involves handling goods from overseas. Spider bites leave small puncture marks on the skin, which can be painful and cause redness and swelling. In severe cases, a spider bite may cause nausea, vomiting, sweating and dizziness.
Very rarely, a spider bite may cause a severe allergic reaction. A wasp or hornet sting causes a sharp pain in the area that's been stung, which usually lasts just a few seconds. A bee sting feels similar to a wasp sting, but the sting and a venomous sac will be left in the wound. You should remove this immediately by scraping it out using something with a hard edge, such as a bank card. Most people won't have severe symptoms after being bitten or stung by an insect, but some people can react badly to them because they've developed antibodies to the venom.
You're more likely to have an allergic reaction if you're stung by an insect. The reaction can be classed as:.
Although insect bites and stings are a common cause of anaphylaxis, it's rare to experience anaphylaxis after an insect sting, and it's rarely fatal. If you have a large localised reaction LLR after being bitten or stung by an insect, a large area around the bite or sting will swell up. The area may measure up to 30cm 12in across, or your entire arm or leg could swell up.
The swelling will usually last longer than 48 hours, but should start to go down after a few days. This can be painful, but the swelling won't be dangerous unless it affects your airways.
If you're bitten or stung many times by one or more insects, your symptoms will be more severe because a larger amount of venom will have been injected.
You're more likely to have a systemic reaction SR if you've been bitten or stung before and become sensitised, particularly if it was recently. People who've been sensitised to bee stings are more likely to have an SR than people who are stung by wasps. It's rare for an SR to be fatal, particularly in children, although someone with an existing heart or breathing problem is at an increased risk. Read about treating insect bites and stings. Most insect bites and stings cause small reactions that are confined to the area of the bite localised reactions.
They can usually be treated at home. As soon as you've been stung by a bee, remove the sting and venom sac if it's been left in your skin. Do this by scraping it out, either with your fingernails or something with a hard edge, such as a bank card. When removing the sting, be careful not to spread the venom further under your skin and don't puncture the venom sac.
Don't pinch the sting out with your fingers or a pair of tweezers because you may spread the venom. If a child has been stung, an adult should remove the sting. Wasps and hornets don't usually leave the sting behind, so they could sting you again.
If you've been stung and the wasp or hornet is still in the area, walk away calmly to avoid being stung again. Most insect bites and stings cause itching and swelling that usually clears up within several hours. If local swelling is severe, your GP may prescribe a short course of oral corticosteroids , such as prednisolone, to take for 3 to 5 days.
If you have an allergic reaction after being bitten or stung, even if it's just a skin rash hives , your GP may prescribe an adrenaline pen an auto-injector and show you how to use it.
You'll also be referred to an allergy clinic for further tests and treatment. If you develop blisters after being bitten by an insect, don't burst them because they may become infected. Blisters don't usually cause pain unless they rupture burst and expose the new skin underneath. If possible, use an adhesive bandage plaster to protect the blistered area. See your pharmacist if the bite or sting fills with pus and feels tender to touch, your glands swell up and you feel unwell with flu-like symptoms.
Your pharmacist may prescribe oral antibiotics medicines to treat infections caused by bacteria. You'll need to take these as instructed, usually 2 to 4 times a day for 7 days. If you have the symptoms of a systemic reaction SR , it could lead to anaphylactic shock. Anaphylaxis may need to be treated with an adrenaline injection, antihistamines, oxygen or an intravenous drip directly into a vein.
If previous insect bites or stings have caused a large skin reaction, such as redness and swelling more than 10cm 4 inches in diameter, your GP may refer you to an allergy clinic. The criteria for referring someone to an allergy clinic may vary depending on what's available in your local area.
Immunotherapy desensitisation or hyposensitisation is a possible treatment option if you're allergic to wasp or bee stings. It involves being injected with small doses of venom every week to alter your body's immune response to venom. You need to be observed after each injection to make sure you don't have an allergic reaction to the treatment.
Over time, your body becomes used to the venom desensitised and you're no longer at risk of anaphylaxis. When a high enough dose has been reached, the injections are given at four to six-week intervals for a further two to three years. Your allergist allergy specialist will decide how much venom is injected and how long the injections need to continue for. This will depend on your initial allergic reaction and your response to the treatment.
For more information about immunotherapy, see treating allergies. If you've been bitten by a tick, remove it as soon as possible to reduce the risk of getting a tick-borne infection, such as Lyme disease a bacterial infection that causes a pink or red circular rash to develop around the area of the bite.
If you suspect that you have a tick bite, complete our self-help guide to assess your symptoms and find out what to do next. Return to Symptoms. Next Review Date:. Avoid scratching the bite because it will cause further swelling and increase the risk of infection. Most tick bites will heal within three weeks. Read more about how Lyme disease is treated. Secondary bacterial infections are a common complication of insect bites and stings.
They include:. An infection can occur if you scratch an insect bite or sting, or it may be introduced at the time you're bitten. Infections are usually treated with antibiotics. Lyme disease is an infection caused by a species of tick known as Ixodes ricinus. Ticks aren't insects — they're small arachnids. Your risk of developing Lyme disease is increased if you spend a lot of time in woodland or heath areas as these areas are where tick-carrying animals, such as deer and mice, live.
The initial infection is characterised by a red rash that gradually expands outwards from the site of the bite. Antibiotics are usually used to treat the infection.
If untreated, the long-term effects of Lyme disease include problems with the nervous system, such as:. The condition can also damage the joints, which can lead to arthritis and, occasionally, heart problems, such as inflammation of the heart muscle myocarditis and inflammation of the fluid-filled sac that surrounds the heart pericarditis.
West Nile virus is an infection with flu-like symptoms that is spread by mosquitoes. There have been no reported cases of West Nile virus in the UK, but there have been cases elsewhere in the world. Malaria is a tropical disease caused by an infection of the red blood cells.
It can be transmitted to humans by the bite of an infected mosquito. Each year, there are around 1, cases of malaria in travellers returning to the UK. A certain type of malaria caused by the parasite Plasmodium falciparum is potentially fatal.
It accounts for more than half of all cases of malaria in the UK each year. It's particularly important to follow this advice if you've had a bad reaction to an insect bite or sting in the past.
Ticks are small arachnids that are mainly found in woodland areas. Previous research has shown that the human immune system reacts to mosquito spit. However, it wasn't clear to what extent, because the effects were studied primarily in the immune systems of mice. But in the new study, published today May 17 in the journal PLOS Neglected Tropical Diseases , the researchers created a close replica of a human immune system in mice.
The researchers noted that the immune system they created in the mice didn't have every component of a human immune system and that they want to conduct further studies to get a more complete picture. In the study, the researchers, from the Baylor College of Medicine in Texas, injected baby mice with human hematopoietic stem cells — which later turn into various types of blood cells, including immune system cells — that were taken from umbilical cords.
When the mice grew up and had a well-established "human" immune system, the researchers held an open vial of mosquitoes against the footpads of each mouse.
The insects bit each mouse around four times. By analyzing blood bone marrow, skin and spleen cells from the mice, the researchers found that a number of immune cells remained active even seven days after the mice were bitten. Minus Related Pages. Credit: Getty Images. Anti-itch cream for a mosquito bite. Treat clothing and gear with permethrin. Links with this icon indicate that you are leaving the CDC website.
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