Allergy to hymenoptera bites

What are Hymenoptera?

Hymenoptera are free-living flying insects or insects used for honey production. They are divided into three families: vespoids (wasps and hornets), apoids (bees and bumblebees) and formicoids or ants. The first two are undoubtedly the main ones, although in some countries there are highly aggressive ants with very toxic poisons.

What do hymenopteran stings produce?

When stinging, hymenoptera inject toxic substances or venom that are complex mixtures of enzymes (phospholipases, hyaluronidases) and proteins, some of which are potent allergens, although they themselves have their own pharmacological activity (direct mast cell degranulator).

The result of a hymenoptera sting is a direct local toxic reaction causing pain, swelling, redness and itching, which subsides within hours or a few days. But after a first sting, people with a genetic predisposition to allergy can produce an IgE-mediated immune response that can cause two types of manifestations:

  • Localized reactions with great inflammation, extended to the joints, lasting one or more days and causing a lot of pain and discomfort. Requires treatment of symptoms with anti-inflammatory drugs and corticosteroids.
  • Generalized reactions. These are of rapid onset, within a few minutes, and are manifested by urticaria and angioedema. However, they can be much more severe, reaching anaphylaxis with the development of digestive disorders (vomiting, diarrhea, abdominal pain), respiratory disorders (bronchial asthma) and more severe alterations such as glottic edema and confusional state. The most serious picture is hypotension and shock (anaphylactic shock), which can be fatal if not treated immediately.

How is allergy to hymenoptera stings diagnosed?

The clinical history is essential to determine the type of hymenoptera that has stung the patient. In many cases patients are beekeepers, gardeners and farmers who are familiar with the insect. In other cases, photographs and images should be shown to clarify the identification.

It is necessary to differentiate between an exaggerated toxic reaction and an allergy. The severity of the general reaction, if any, should be determined.

Blood tests are available to determine specific IgE levels which are not directly related to the severity of the reaction, so skin testing is usually necessary.

Skin tests consist of intradermal inoculation of very low concentrations of controlled extracts of venoms, mainly Apis mellifera (bee), Vespula spp or Polistessp (wasp).

Due to the risk posed by intradermal tests, they must be performed under medical supervision and under safe conditions in order to be able to deal with any unexpected reactions while the study is being carried out.

What is the treatment for hymenoptera bites?

Immunotherapy with hymenoptera venom is accepted worldwide for its high effectiveness and the extraordinary power of protection achieved when the appropriate vaccines are administered progressively and always under medical control. It is essential to perform it in subjects who have suffered severe anaphylactic or local reactions and advisable in the rest due to the possibility of new stings generating more serious symptoms.

The patient diagnosed with hymenoptera allergy should be trained in the self-administration of adrenaline and in the use of antihistamines and corticoids while attending an emergency center.