The Mölnlycke Health Care blog
Allergies: A Reason to Overreact!
It is that time of year again – the time of year when I have to check my pockets and bags to be sure I have an epipen handy and that it is in date. The time of year when I need to be sure I have a letter from my doctor explaining that I need to carry an injection with me. The time of year when – in short – wasps start flying…
Why is this? Well, I have been told that I have an extreme allergy to wasp stings. My body overreacts to wasp venom – and there is a high risk that I would have an anaphylactic response to a wasp sting, which could well be fatal. I have not put it to the test just yet! An anaphylactic response is a systemic response to an allergen, which can cause respiratory difficulty and a sudden drop in blood pressure that may lead to cardiovascular collapse. Anaphylactic shock can lead to death if left untreated!
What is an allergy? An allergy is an immune reaction to an environmental agent that results in a symptomatic reaction. The “environmental agent” here is an “allergen”, which is a substance that in some individuals can cause an allergic or hypersensitive reaction but is not normally considered harmful.1 There are different classifications based on hypersensitivity level. For example, type I creates an immediate reaction, such as the anaphylactic reaction described above, while type IV causes a delayed reaction. More about that a bit later.
Allergy development We hear this term, “allergy”, in relation to environmental antigens, such as pollens, dust mites, moulds, foods, chemicals and latex proteins. It is important to note that not all allergies are alike. In some types of allergies, once it has developed, the level of sensitivity may become greater with each exposure, making the reaction worse. Individuals who do not express any allergic reactions initially still have the potential to develop allergy after exposure over time. In these cases, exposure to a particular antigen (such as a natural rubber latex protein or a chemical) results in a marked increase - hypersensitivity - to that antigen, now an allergen. This may result in significant medical consequences. Outward expression of the hypersensitivity or allergy may include hives (raised, fluid-filled, red areas on the skin – usually intensely itchy), rhinitis, (runny nose) shortness of breath and anaphylaxis (this is very bad news!), among others.
The reason this topic comes to mind, other than spring being in the air, is that a friend happened to mention that she had a swollen and sore throat, which she thinks may have been due to eating kiwi fruit. She did not start out with any sensitivity to kiwi but had experienced a milder, but similar, reaction in the past, followed by a more acute reaction recently. Alarm bells rang in my head. Again, some types of allergy get worse with repeated exposure – particularly this kind, a bit like one might react to repeated aggression. Eventually one reacts to a threat even if it is not really there. While certain allergens come to mind immediately because we experience or see them on a daily basis -- for example, food or pollen allergies, other allergies are less visible.
A good example of this less visible allergy type is latex. In healthcare, we think about and discuss this frequently because barrier protection in the form of surgical or examination gloves is essential to the trade. What happens, though, when a healthcare practitioner whose livelihood depends on being able to wear gloves more or less constantly develops an allergy to latex? (Several latex-free options exist, of course, but my point is simply that this kind of allergy can have a crippling effect on healthcare professionals, as the latex allergy is one of the kinds that worsens with repeated exposure.)
The aforementioned allergy types I and IV are important in the world of latex allergies and surgical gloves. As discussed earlier, type I causes an immediate reaction, within five to 30 minutes. The body’s immune system overreacts to the allergen, such as latex proteins. Type IV is typified by a delayed reaction (six to 48 hours). The body’s immune system reacts to chemicals in gloves. This type of response can occur in people with type I latex allergy. (It is important to note that type IV is more correctly described as a hypersensitivity rather than an allergy.) The discussion about repeated exposure is particularly relevant and important to understand – practitioners working in the surgical field wear multiple pairs of gloves every day and their allergic response is directly relevant to being able to do their job.
1. C A Janeway et al, “The induction, measurement, and manipulation of the immune response,” ImmunoBiology: The Immune System in Health and Disease, fourth ed (New York: Elsevier Science Ltd/Garland Publishing,1999) 33-75.