Allergic Reactions to Bites and Stings

Most insect bites and stings result in a localised itch and swelling that settles within a few days. Severe allergic reactions (anaphylaxis) to insects are usually due to bees, wasps or the Australian Jack Jumper ant. Insect bites are a less common cause of anaphylaxis than insect stings. Effective treatments are available to treat allergic reactions to bites and stings.

pdfASCIA PCC Allergic reactions to bites and stings 2019133.63 KB

Stinging insects are a common cause of anaphylaxis

Allergies to venoms from stinging insects (bees, wasps and ants) are one of the most common causes of severe allergic reactions (anaphylaxis) in Australia. Symptoms include an all over rash, swelling of tongue or throat, trouble breathing, abdominal pain, diarrhoea, vomiting and a drop in blood pressure (shock).

Allergen immunotherapy can reduce the severity of allergy

Allergen immunotherapy (AIT) is also known as desensitisation and can help to switch off allergy over time and this is effective treatment for allergies to bee and wasp stings. Rebates are available for this treatment on the PBS in Australia and by Pharmac in New Zealand.

There is currently only limited access to Jack Jumper ant AIT.

AIT is not yet available for treating tick allergy or reactions triggered by other species of ants and wasps.

AIT is not helpful in patients with large local swellings alone and may not be necessary in patients with isolated rashes. For these reasons, people should be evaluated by a clinical immunology/allergy specialist before initiation of AIT is considered.

The duration of treatment is usually 3-5 years.

Diagnosing the cause of your allergy

A doctor will normally ask a series of questions that may help to narrow down the list of likely cause of reaction. This approach will help to exclude conditions that can sometimes be confused with anaphylaxis. Skin testing or blood allergy testing can help confirm or exclude potential triggers.

Natural history of allergic reactions to stinging insects

Isolated local reactions:

Generalised reactions without life threatening features:

Anaphylaxis:

Severe allergic reactions (anaphylaxis) can be fatal

Anaphylaxis from stinging insect allergy results in an average of three deaths per year in Australia. Older people and those with difficult breathing are at greatest risk and should be seen by a clinical immunology/allergy specialist to develop a strategy for managing subsequent stings.

Effective emergency treatment for anaphylaxis is available

Patients at risk of anaphylaxis are advised to:

First aid is adequate for the treatment of minor allergic reactions to bees

Bees usually leave their barbed sting in the skin and die. Flicking the sting out as soon as possible will reduce the amount of venom injected. Use the edge of your fingernail, a car key or credit card. If possible try not to squeeze the venom sac, as this may increase the amount of venom injected. By contrast, wasps and bull ants rarely leave their sting in the skin. Cold packs and soothing creams often help for minor reactions. Oral antihistamines can be useful for treating itch. Very large and uncomfortable local reactions may need cortisone tablets to settle the swelling.

Bites are a less common cause of anaphylaxis than insect stings

Local allergic reactions to biting insects (such as itchy bites to mosquitoes, midges and March flies) tend to become less severe with time.

Anaphylaxis to biting insects is very rare, even when the swellings are large and uncomfortable.

Caterpillars can cause severe irritation from touching their spines, which are attached to venom sacs underneath the skin. In rare cases they can trigger anaphylaxis.

Ticks are arachnids that bite, rather than insects. Sometimes large local swelling and inflammation can arise at the site of a bite and last several days. Such reactions are usually due to mild allergy to the tick. Anaphylaxis can occur to the Australian paralysis tick, Ixodes holocyclus when the tick is disturbed, so ticks should be freeze dried before they are removed. 

Anaphylaxis following snake bites have been reported, although these are very rare.

Common bull ants can cause anaphylaxis.

Prevention of bites and stings

Bites from midges and mosquitoes are best avoided by covering up as much as possible. Avoid being outdoors in the early morning or at dusk, and use an insect repellent containing DEET.

After being outdoors, check for ticks if living in an endemic area. Ticks should not be removed from allergic people until the person is in an emergency medical facility. This is because allergic reactions often occur when the tick is removed.

Honeybees normally only sting in self defence. The best protection is light coloured clothing, covering much of the body, including wearing shoes and avoiding perfumes.

Wasps tend to nest in logs, walls or underground. They are generally more aggressive than bees and attracted to food and drink. Therefore, it is important that you don't drink blindly from open drink cans when outdoors.

Stings and bites often occur on bare feet, so people with allergies to bites or stings should always wear shoes when outdoors.

When gardening, wear long sleeves, long pants and gloves. Tuck shirt into pants and pants into socks to prevent tick bites.

Avoid provoking bees and wasps.

Where possible, drive with the windows up.

Have nearby ant, bee or wasp nests removed by professionals. This is also relevant to schools and early childhood education/care centres, particularly if they have children enrolled with stinging insect allergy.

 

© ASCIA 2019

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to immunology/allergy research go to www.allergyimmunology.org.au

 

Updated May 2019