Peanut allergy
Synonyms and keywords: Groundnut hypersensitivity; nut allergy

# Overview
Peanut allergy is a type of food allergy, distinct from nut allergies.

# Pathophysiology
It is a hypersensitivity to dietary substances from peanuts causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people.

# Epidemiology and Demographics
The Asthma and Allergy Foundation of America estimates that peanut allergy is the most common cause of food-related death.. Prevalence among adults and children is similar  around 1%  but at least one study shows it to be on the rise in children.

# Natural History, Complications and Prognosis
25% of children with a peanut allergy outgrow it.  It is usually treated with an exclusion diet and vigilant avoidance of foods that may be contaminated with whole peanuts or peanut particles and/or oils.  The most severe peanut allergies can result in anaphylaxis, an emergency situation requiring immediate attention and treatment with epinephrine.
The Centers for Disease Control reported 12 to 20 food allergy deaths in 2007 . Other sources put the number of deaths from assorted food allergies at approximately 125 people in the United States.
Peanuts are the most common source of fatal allergic reactions.
Reports of death from peanut allergy in 2008 include:
- Andrew Michael Smith (age 8) died February 2008 after he accidently came into contact with peanut allergens at home. 
- Carol Kiener, (age 66) died March 2008 after suffering a severe allergic reaction to peanuts.
- Paul Anthony Thurston (age 30) died April 2008 after being served a peanut butter sandwich in jail.
- Daniel Sargent (age 30) died July 2008 after eating a cookie that had peanut butter in it at a party. 
- Brian Hom II (age 18) died July 2008 after eating a dessert containing traces of peanuts while at a resort in Cabo San Lucas. 
- Dexter Skinner (age 16) died July 2008 after eating a chocolate bar.  
The 2005 death of Christina Desforges, which was initially reported as a result of exposure to peanuts, spurred many parents to speak out about the dangers of peanut butter and jam sandwiches at schools or peanut shells on the floors of restaurants. However, according to a coroner's statement in March 2006, Ms. Desforges did not die of anaphylactic shock caused by a kiss from her boyfriend after he ate a peanut butter snack, but in fact died as a result of asthma-linked respiratory failure, which was triggered by tobacco smoke at a party.  Research by Jennifer Maloney suggests that peanut allergens normally leave the saliva after about an hour.

# Diagnosis

## Symptoms
Symptoms of peanut allergy are related to the action of Immunoglobulin E (IgE) and other anaphylatoxins, which act to release histamine and other mediator substances from mast cells (degranulation). In addition to other effects, histamine induces vasodilation of arterioles and constriction of bronchioles in the lungs, also known as bronchospasm (constriction of the airways).
Symptoms can include the following:
- vomiting
- diarrhea
- urticaria (hives)
- angioedema (swelling of the lips, face, throat and skin)
- acute abdominal pain
- exacerbation of atopic eczema
- asthma
- anaphylactic shock
The British Dietetic Association warns that: "If untreated, anaphylactic shock can result in death due to obstruction of the upper or lower airway (bronchospasm) or hypotension and heart failure. This happens within minutes to hours of eating the peanuts. The first symptoms may include sneezing and a tingling sensation on the lips, tongue and throat followed by pallor, feeling unwell, warm and light headed. Severe reactions may return after an apparent resolution of 1-6 hours. Asthmatics with peanut sensitivity are more likely to develop life threatening reactions."

# Treatment
Food allergy experts at the Duke University Medical Center believe that an immunotherapy treatment for peanut allergies will be available to affected people within 5 years.   Immunotherapy would be used to treat a person's immune response to peanuts from an allergic reaction to a nonallergic response.  This is great news for the parents of affected children and adults living with the allergy.  The condition is actually becoming more common affecting about 1% of children in total.  The number of affected people doubled between 1997 and 2002.

## Prevention

### Allergen-Free Peanuts
As with most allergies, avoidance is the key. All labels for foods, medicines, cosmetics, creams, and ointments should be read. A history of allergic reactions after consuming a peanut may suggest an allergy.
While several companies have developed promising drugs to counteract peanut allergies, trials have been mired in legal battles.
On July 20, 2007, the North Carolina Agricultural & Technical State University announced that one of its scientists, Dr. Mohamed Ahmedna, had developed a process to make allergen-free peanuts.  Initial testing showed a 100 percent inactivation of peanut allergens in whole roasted kernels, and human serums from severely allergic individuals showed no reaction when exposed to the processed peanuts.  Food companies have expressed an interest in licensing the process, which purportedly does not degrade the taste or quality of treated peanuts, and even results in easier processing to use as an ingredient in food products.