Peanut Allergy – Symptoms, Causes, Cure, Treatment

What is Peanut Allergy?

A peanut allergy is different from other nut allergies as it is actually a legume, not a nut. Those with a tree nut allergy may or may not also have a peanut allergy and vise-versa. A peanut allergy is a type 1 hypersensitivity reaction to peanuts. Once peanuts are ingested, if one has an allergy, the body detects it as a foreign object and initiates an allergic reaction. Peanut allergy can manifest as a mild allergic reaction with minimal symptoms and irritations, or as an anaphylactic condition that requires immediate medical response.
People with this type of allergy avoid ingesting foods that cause a reaction, whether it be actual peanuts or food that has touched peanuts.

Pathophysiology of Peanut Allergy

Like all allergic reactions, when contaminated food is ingested and absorbed by the body, the body responds by secreting Immunoglobulin E and anaphylatoxins. Once this happens, the mast cells release histamine and other inflammatory chemicals. Histamine is responsible for the dilation of arterioles leading to erythema, rashes and itching. It also causes bronchoconstriction or bronchospasm, which causes difficulty in breathing. Other mechanisms allows the body to eliminate the toxin from the body to reduce allergy symptoms.

Symptoms and Signs of Peanut Allergy

The symptoms for peanut allergy include:

• Diarrhea
• Vomiting
• Hives or urticaria (elevated and bordered skin eruptions)
• Angioedema, which results in swelling of the face, lips, skin and throat
• Atopic eczema
• Abdominal pain
• Itching

More severe symptoms that may indicate anaphylaxis include:

• Tingling sensation on the lips and throat
• Difficulty of breathing
• Shortness of Breath
• Wheezing
• Stridor
• Asthma
• Pallor
• Light-headedness

When anaphylaxis is not treated, it can lead to shock and possible death of the patient. This happens because of severe obstruction to the airways, and severe dilatation of the blood vessels, leading to circulatory collapse. Anaphylactic shock may happen immediately following or up to a few hours after the ingestion of peanuts. Patients with asthma are more likely to develop severe allergic reactions because of respiratory compromise.

Picture – Peanut allergy

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Causes of Peanut Allergies

The exact cause of peanut allergy is unknown, but several factors have been considered in the development of the condition. These include:

• Exposure to soy milk and products during infancy
• Maternal exposure to peanuts
• Short breastfeeding time
• Exposure to peanut oils in certain products

These hypothesized causes have had inconclusive studies conducted on them and as of now, just theories. In fact, the American Academy of Pediatrics allows the consumption of peanuts during pregnancy, breastfeeding, and as soon as the child can eat solid foods. The most definitive cause of peanut allergies is related to the hygiene hypothesis. This hypothesis states that a lack of exposure to certain substances and foods during childhood may cause an allergy because the body is not desensitized to the food early. One study also supported the hygiene hypothesis as observed in children in the United Kingdom and Israel. Children in Israel are given peanuts at an earlier age as compared to children in the UK. The study showed a 10 fold increase in the occurrence of the allergy to peanuts among children in the United Kingdom as compared to that in Israel.

Diagnostic Tests for Peanut Allergy

Diagnostic tests are needed to determine if a person has a peanut allergy or has a different condition related to peanuts or other legumes such as food intolerance or food poisoning. Aside from describing the symptoms and physical examination, further tests include:

Food diary

A food diary is required to record the intake of food over a period of time and the associated symptoms that come with it. A food diary is a useful tool for both the patient and the physician in identifying certain foods that may have caused the allergic reaction.

Elimination Diet

When the doctor has an idea on what possible foods may have caused the allergy, an elimination diet is requested whereby the patient will need to eliminate certain foods in their diet. After one to two weeks, those foods are introduced one at a time. When an allergic reaction happens, then it is associated with the type of food last ingested.

Blood Tests

Immunoglobulin E is traced in the blood to detect the presence of allergy. When these are not present, it could be a sign of intolerance to peanuts or other foods.

Skin Tests

This involves the injection of certain food substances under the skin in a localized area. After 30 minutes, the skin patch is checked for signs of an allergic reaction such as itching, redness and increase in the size of the wheal.

Treatment for Peanut Allergy

Most people with peanut allergies end up avoiding it as the only way of managing the allergic reaction. However, there are certain managements to employ in order to eradicate the allergy. These include:

Oral desensitization

This involves the introduction or ingestion of small portions of peanut in order for the body to identify it and be able to adapt to the presence of the food in the body. Oral desensitization involves the exposure of escalating doses of peanut until the body no longer reacts to high amounts of peanut. This management is the only therapy to eradicate allergy to certain foods. Injected peanut desensitization was used in 1996, but has resulted in the death of a patient after experiencing laryngospasm. The use of the injection method of desensitization was eliminated during that time.

The symptoms of peanut allergy, once it has occurred, should be managed to prevent the occurrence of life-threatening reactions. The drugs used for managing peanut allergy symptoms include:

Antihistamines

Antihistamines such as diphenhydramine and cetirizine help in reducing allergic symptoms due to binding at histamine receptor sites, thereby preventing histamine from producing allergic symptoms.

Epinephrine

Epinephrine is an emergency drug used to manage anaphylactic reactions. It is given by injection. Patients are taught to self-inject epinephrine in case of a reaction.

Patients are also advised to wear medical bracelets indicating allergy to peanuts. Medical ID bracelets allow rescuers and other people to identify the condition of the patient in case an anaphylactic reaction occurs and the patient cannot confirm the allergy.

Statistics and Facts

Peanut allergy is one of the most common forms of food allergies, with a prevalence of 1% in children and adults. Although the prevalence is minimal, it causes 10 deaths per year in the United States.

Peanut allergy is different from peanut intolerance. Intolerance does not involve the immune system and does not result in life-threatening anaphylaxis. People with peanut intolerance may eat small amounts of peanut without experiencing symptoms.