​Kembara Xtra - Medicine - Food Allergy

​Kembara Xtra - Medicine - Food Allergy 
An undesirable health consequence that is caused by a specific immune response that may be reproduced after being exposed to a certain food is what is meant when we talk about food allergy.
Reaction of hypersensitivity caused by exposure to specific foods; may involve IgE-mediated and non-IgE-mediated processes.
System(s) affected: gastrointestinal (GI), heme/lymphatic/immunologic, pulmonary, skin/exocrine Synonym(s): allergic bowel illness; dietary protein sensitivity syndrome Affected organs and systems: gastrointestinal (GI), heme/lymphatic/immunologic, pulmonary, skin/exocrine 

Epidemiology 

 All ages are affected, however newborns and children are more likely to be affected than adults.
● Predominant sex: male > female (2:1)
a disproportionately negative effect on patients who are underserved or minority
Incidence
During their first year of life, approximately 2.5% of infants are affected by hypersensitivity reactions to cow's milk.

Prevalence

The percentage of people who have an IgE-mediated food allergy as determined by a food challenge is three percent.

The prevalence of food allergy among self-reporting children is 12%, whereas the prevalence among adults is 13%.

● The four foods that most frequently cause allergic reactions in infants and toddlers are cow's milk (2.5% of cases), eggs (1.3%), peanuts (0.8%), and wheat (0.4%).

Among adults, those who are allergic to fish (0.4%), peanuts (0.6%), tree nuts (0.5%), and shellfish (2%), respectively, are more prevalent.
Having a food allergy is typically a temporary condition, since only three to four percent of children older than four years old continue to suffer from the condition.

 Twenty percent of youngsters who are allergic to peanut protein may outgrow their sensitivity by the time they start school.

Causes and effects: etiology and pathophysiology 

Allergic reaction that is induced either by immunologic processes (such as IgE-mediated or non-IgE-mediated allergic responses) or by mechanisms that are not mediated by immunology.

Any substance that is consumed has the potential to trigger allergic reactions:
Cow's milk, egg whites, wheat, soy, peanuts, fish, tree nuts (such as walnuts, cashews, and pecans), and shellfish are among the foods that are most frequently linked to the development of celiac disease.
Several food colors and additives have the potential to provoke allergic-type reactions in people who do not have IgE antibodies.
Genetics Despite the fact that allergy disorders most certainly have a hereditary component, the genetics behind them are not simple and are not monogenic.
Studies using human leukocyte antigen (HLA) to investigate peanut allergy have repeatedly been unsuccessful in establishing relationships.
When there is a history of food sensitivity in a family, there is a greater chance that succeeding siblings will also be sensitive to food; this risk can reach as high as 50%.

factors of danger 

Patients who have a propensity to allergies or atopic dermatitis have a higher risk of developing a hypersensitive reaction to food.
a history of reactivity to foods in the family


Prevention 

 Research has shown that high-risk infants who consume peanut protein at a rate of 6 grams per week had a reduced chance of developing peanut allergy by the age of 5 years. As a result, global infant feeding guidelines now advocate beginning the introduction of peanut and other complementary foods at the age of 5 months.
Epinephrine autoinjectors should be kept close at hand for individuals who have a history of anaphylaxis or who are at risk for developing the condition.

Conditions That May Be Linked To It Include Atopic Dermatitis And Eosinophilic Esophagitis

Presenting History 
● Symptoms after food ingestion/exposure—usually within
30 minutes of ingestion but could be delayed 4 to 8 hours
● Document a temporal relationship between symptoms
and suspected food. Include the way in which the food was cooked as well as the amount of food that was consumed.

Identify the difference between a genuine food allergy or hypersensitivity and food intolerance, which can cause symptoms that are quite similar.
GI symptoms that are more prevalent include bloating, flatulence, occult bleeding, nausea, and vomiting. GI symptoms that are less common include malabsorption, protein-losing enteropathy, eosinophilic enteritis, and colitis.

 Dermatology: urticaria/angioedema, atopic dermatitis, pallor, or flushing are the most common skin manifestations; contact rashes are less prevalent.
Respiratory - These include the more prevalent conditions of allergic rhinitis, asthma, and bronchospasm, as well as stridor, cough, and serous otitis media.
Less frequently seen: pulmonary infiltrates (Heiner syndrome), pulmonary hemosiderosis Neurologic Less frequently seen: migraine headaches Other Less frequently seen: systemic anaphylaxis, vasculitis, ocular injection, conjunctival edema, and periorbital swelling
– The association between exercise, nonsteroidal anti-inflammatory drug use, and alcohol consumption

Examine the patient's vital signs and growth parameters Look for evidence of allergic disease, focusing particularly on pulmonary and skin exams Look for any other exam findings that are relevant to the patient's clinical presentation

Differential Diagnosis 
● Nonimmune food intolerance such as enzyme deficiencies (e.g., lactose intolerance)
• Ingestion of poisonous foods (such as scombroid fish or food sickness caused by germs);
gastrointestinal (such as irritable bowel syndrome, celiac sprue, dumping syndrome, inflammatory bowel diseases, and so on), dermatological, respiratory, neurological, and mental (such as generalized anxiety disorder, personality disorders, and so on) conditions.
Oral allergy syndrome – The oral allergy syndrome is caused by proteins in pollen that react with one other in a cross-reactive manner (for instance, people who are allergic to birch tree pollen usually exhibit cross-reactivity to fresh apples and pears).
Galactose--1,3-galactose (-gal) — Following a bite from a lone star tick, susceptible people may develop an IgE sensitivity to -gal. This sensitivity manifests as delayed anaphylaxis, which typically occurs between three and six hours following the consumption of mammalian meat. The patient's medical history is analyzed, and the diagnosis may be verified by specific IgE to beta-gal.


Results From the Laboratory Initial Examinations (lab, imaging)
CBC with differential: the presence of eosinophils is suggestive of allergic rhinitis.
Using commercially available extracts with varying sensitivities or fresh food to perform epicutaneous (prick or puncture) allergy skin tests can document IgE-mediated immunologic hypersensitivity.
The use of the food under suspicion in a skin test can be useful. If the results of the skin test come back negative, an oral challenge could help with the diagnosis. When testing is done on fresh food, the correlation between a positive skin test and a positive challenge increases to 90% (this means that a positive skin test correlates with a positive challenge). The overall correlation between allergy skin testing that is commercially accessible and an oral food challenge is 60%.
Because skin testing has a high sensitivity (low likelihood of false-negative results) but a low specificity (high rate of false-positive results), it should only be used to test for antigens that have been detected in the patient's medical history.

Food-specific IgE assays, such as the radioallergosorbent test (RAST) and the fluorescent enzyme immunoassay (FEI), detect specific IgE antibodies to the foods that cause an allergic reaction. These tests are less sensitive than skin testing.
– When attempting to detect a food allergy, relying solely on a serum test can lead to an incorrect diagnosis of actual food allergic sensitivity. This is especially true in children who suffer from atopic dermatitis. Do not use a panel. Check the patient's history to see whether they have any specific IgE to foods.
It may be beneficial to perform peanut-specific IgE testing at regular intervals, say once every two years. If the patient's level of peanut-specific IgE drops to less than 0.5 kU/L, a peanut oral challenge carried out under medical supervision may be beneficial. Prior to the oral challenge, you should think about getting a fresh food skin test with peanut protein.

 Component-resolved diagnosis (CRD) is a new diagnostic tool that detects specific allergenic proteins in a variety of foods in order to identify specific IgE to allergenic proteins rather than the overall allergen. This method is particularly effective for some nuts, such as peanuts.

Patch testing to assess delayed-sensitivity immunologic reactions in individuals with eosinophilic esophagitis and atopic dermatitis provides only a minimal advantage.

It is not recommended to perform widespread allergy skin testing or serum IgE testing since these tests have a low predictive value when there is no clinical history to correlate them with.

Assays measuring leukocyte histamine release to detect circulating immune complexes have limited application in clinical practice.

The provocative injection and the sublingual test aren't very helpful in making a diagnosis of food allergy, and the leukocytotoxic assay hasn't been validated yet.

Provocative neutralization, lymphocyte stimulation, hair analysis, and applied kinesiology are some of the other questionable diagnostic treatments that should be avoided.


Diagnostic Methods and Other Procedures

The best way to confirm a food allergy is using tests that involve both elimination and challenge:
Take the food that may be causing the problem out of your diet for a period of one to two weeks.
Keep an eye on the patient's current symptoms. Perform an oral challenge with the suspected meal under medical supervision if the symptoms go away or significantly improve. Ideally, this challenge should be carried out in a double-blind, placebo-controlled manner; nonetheless, open oral food challenges are the type that are most typically used in ordinary practice.
Patients with a history of anaphylaxis should not undergo an oral challenge until a significant amount of time has elapsed since the reaction that caused anaphylaxis and IgE sensitivity has decreased or vanished. The majority of allergy reactions occur between 30 minutes to 2 hours after a challenge has been given. There have been reports of delayed reactions lasting anywhere from 12 to 24 hours.
If the patient's medical history and test results are ambiguous, you should consider referring them to a gastroenterologist for an endoscopy and maintain watchful surveillance.
The Interpretation of Tests
In cases of food allergies, identifying pathologic alterations on tissue biopsy is extremely rare; however, inflammatory changes can occasionally be found in the gastrointestinal system. On an esophageal biopsy, the presence of more than 15 to 20 eosinophils per high-power field is required to make the diagnosis of eosinophilic esophagitis.


Management 

Patients who have a severe food allergy should be extremely careful when avoiding foods. Offending food avoidance is the most effective treatment. They should always keep epinephrine with them so that they can administer it to themselves in case they unintentionally consume the allergen-containing food and experience an acute reaction.

Immunotherapy has shown promise as a treatment for a variety of food allergies. The Food and Drug Administration (FDA) has only recently given its approval for the use of peanut (Arachis hypogaea) allergen powder in oral immunotherapy (OIT) for peanut-allergic children aged 4 to 17 years old. OIT to other foods, sublingual immunotherapy (SLIT), and epicutaneous immunotherapy (EPIT) are still considered experimental and are not suggested for patients who are not engaging in carefully regulated and supervised clinical trials. Other forms of immunotherapy, such as OIT to other foods, SLIT, and EPIT, are not considered experimental.
It is not suggested to use food extracts for subcutaneous immunotherapy or hyposensitization (often referred to as "allergy shots").
At the moment, all types of immunotherapy other than OIT are regarded as being in the experimental stage, despite the fact that research studies are currently being conducted.

Medication 

Patients who have a substantial type 1, IgE-mediated hypersensitivity should always have epinephrine on hand for self-injection in the event that they experience an anaphylactic reaction.
Patients should be observed in a medical institution after they have been given epinephrine to treat a systemic anaphylactic reaction to a food. Fifteen to twenty-five percent of patients may require more than one dose of epinephrine.
Antihistamines, when used to treat symptoms, are typically sufficient when dealing with less severe allergic responses.
Cromolyn is not advised for use in the majority of patients who suffer from food allergy because it can increase the risk of anaphylaxis following accidental exposure to peanut protein. Patients aged 4 to 17 years old who are allergic to peanut protein can consider using Palforzia, which has been approved by the FDA to treat peanut allergy.

Alternative Medicine 

Concerning food allergies, there is a lack of conclusive evidence regarding the benefits of herbal medications.

Follow-up patient monitoring as needed many patients are typically seen at least once a year, with follow-up skin tests and/or serum IgE testing as clinically warranted, in order to establish the chance of the condition resolving on its own without medical intervention.


According to the findings of several studies and clinical examinations, the diet
Dietary guidance is recommended to maintain a nutritionally sound diet while avoiding foods to which the patient is sensitive. Strict avoidance of the offending food is also recommended.
The majority of infants will have outgrown their food sensitivities between the ages of 2 and 4 years:
– It is feasible to reintroduce the food that caused the problem into the diet in a controlled manner (this is especially true if the dish in question is difficult to avoid). Before beginning the oral challenge, check for food-specific IgE in the serum or do a food allergy skin test. The development of tolerance can be determined by observing a statistically significant decrease in the wheal width of a skin test or in serum-specific IgE.
- By the age of five years, peanut allergies clear up in 20% of patients.
Over time, children with egg allergy develop clinical tolerance and lose their sensitivity in 42% of cases, whereas children with milk allergy develop clinical tolerance in 48% of cases.
Adults who are hypersensitive to foods, notably milk, fish, shellfish, or nuts, have a tendency to continue to suffer from their allergy for a significant amount of time.

In addition to anaphylaxis and angioedema, complications include bronchial asthma, enterocolitis, eosinophilic esophagitis, and eczematoid lesions.