For many of us, cooler weather is just around the corner. But mosquitoes may still persist into the school months. And that means that there is still the potential for itchy red bites. While most people are familiar with the annoying bumps, a few experience something a bit more intense.

My daughter has had a couple of bites in the past month, but they were a little unusual. Her mosquito bites were impressive hard lumps that covered an area 5-6 centimetres in diameter and lasted weeks before subsiding. They were extremely itchy, red, and warm to the touch.

In fact, there is such a thing as a mosquito allergy. When a female mosquito feeds to obtain a blood meal, she injects saliva into her victim. This saliva contains a variety of proteins that facilitate blood flow, including preventing normal clotting and dilating blood vessels. Unfortunately, some of these salivary proteins can trigger an immune response.

Typically, a person’s first mosquito bite produces no response but primes the immune system. Subsequent bites become itchy and inflamed within 24 hours. After a larger number of bites, the response escalates to produce an itchy red hive. This is the usual reaction in older children and adults.

The most severe reactions are termed an allergic response. A blistering rash, extensive swelling, and bruising can occur. In some cases, an entire limb may swell when bitten - a condition known informally as Skeeter Syndrome. The response is gradual and takes place over hours to days. More conventional allergic responses include rapid development of hives (urticaria), whole body swelling (angioedema), asthma, and - rarely - anaphylaxis. A definitive allergy is diagnosed through a skin test. Due to a limited supply of mosquito allergens, this particular allergy is underdiagnosed.

Bite responses vary in every person, and individual reactions may diminish over many years of exposure. A lucky few may become desensitized and have no reaction. Others become extremely sensitive. A small group go on to develop allergies to mosquito bites. Risk factors include frequent exposure and lowered immune response. People who work or exercise outside may attract mosquitoes through their increased production of carbon dioxide, body odour, and elevated body temperature. In addition, young children, visitors, and those with immunodeficiency disorders may be affected.

Once an allergy is diagnosed, the only treatment is preventing bites. Avoiding mosquito-infected areas, covering up, and using repellents are strategies. Once bitten, symptoms can be reduced by elevating the affected area, applying ice or Calamine lotion, and keeping the bite clean. Topical corticosteroids and oral antihistamines may reduce localized responses. Anaphylactic reactions must be treated with epinephrine and immediate medical attention.