- Diseases, Disorders & Conditions
Allergies And Kinds Of Allergies
Clinical History Of Food Allergy
The clinical syndrome of food allergy should prompt sick people to provide a history containing some or all the following: for very sensitive persons, some tinglimg, itching, and a metallic taste in the mouth occuring while the food is still in the mouth. Within 15 minutes after swallowing the food, some epigastric distress should occur; it may be nonspecific. There may be nausea and, occasioanally with marked sensitivity, vomiting. Abdominal cramping is felt chiefly in the periumbilical area (small bowel phase), and lower abdominal cramping; watery diarrhea can also occur. Allergy reactions to food usually include urticaria. Urticaria may occur in any distribution or there may be only itching of the palms and soles. With increasing cliniacl sensitivity to the offending allergen, anaphylactic symptoms may emerge, including tachycardia, hypotension, generalized flushing, and alterations of consciousness.
In extremely sensitive persons, generalized flushing, hypotension, and tachycardia may occur before the other symptoms. Most people with food allergy feel the offending allergenig foodstuffs, so diagnosis entails confirmation by skin testing or other methods for measuring allerger-specific IgE antibody.
Food Related Anaphylaxis
Food -induced anaphylaxis is the same process involved in acute hypersensitivity to food allergens, except the severity of the reaction is greater in anaphylaxis. Relatively few food-stuffs are involved in food-induced anaphylaxis; the main ones are peanuts, shellfish, and true nuts. Peaople with latex allergy can develop food allergy to banana, avocado, kiwifruit, and other fruits.
• Anaphylaxis to food can be life-threatening
• There is cros-sensitivity betweenlatex and banana, avocado and kiwifruit.
Allergy Skin Testing In Food Allergy
In actual practice, if a person has positive results on one or more skin tests to foodstuffs, an open challenge with the food stuff may be conducted under physician observation. If that challenge is posotive, the most compelling evidence is obtained with a double-blind placebo-controlled food challenge. With comparison of double-blind placebo-controlled food challenge with open food challenge, the frequency of positive reactions decreases by half. It is reasonable to conduct allergy skin tests on patients with vague symptoms who think they have a food allergy, because the negative test results can be used to assure them that food allergy is not the root of the problem. People with food anaphylaxis should strictly avoid offending foods and carry an epinephrine kit.
• Positive results on skin tests and double-blind food challenges can confirm the diagnosis of food allergy.
• If results of food skin tests are negative, food allergy is unlikely.
Stinging Insect Allergy
Clinical phenomena of stinging insect anaphylaxis are similar to all other forms of anaphylaxis. Stings of the head, neck and dorsum of the hands are particularly prone to large local reactions. Thus, the onset of anaphylaxis may be very rapid, often within 1-2 minutes. There are two varieties of reaction to sting: large local and anaphylactic.Pruritus of the palms and soles is the most common initial manifestation and frequently is followed almost immediately by generalized flushing and hypotension. The reason for attaching importance whether a stinging insect reaction is a large local or a generalized one is that allergy skin testig and, if positive, allergen immunotherapy are recommended only for generalized reactions.
Yellow jackets, wasps, and hornets are vespids, and their venoms cross-react to a substantial degree. The venom of honeybees does not cross-react with that of vespids. Unless the person actually captures the insect delivering the sting, uncertainty will likely attend many cases of insect-stinging anaphylaxis. Thus, skin testing is usually conducted to honeybee and each of the vespids.To interpret skin tests accurately, it is helpful to know which insect caused the sting producing the generalized reaction. Often, the circumstances of the sting can help determine the type of insect responsible. Multiple stings received while mowing the grass or doing other landscape jobs that may disturb yellow-jacket burrows in the groung are likely causes of the yellow-jacket stings. A single sting received while near picnic tables or refuse containers at picnic areas is likely from a yellow jacket or possibly a hornet. Stings received while working around the house exterior (painting, cleaning eaves and gutters, attic work) are most likely from wasps.
• Yellow jacket, wasps, and hornets are vespids and their venoms cross-react.
• Venom of bees does not cross-react with that of vespids.
• It is helpful to know which insect caused the sting.
People who have had a generalozed reaction warrant allergen skin testing. People who have had a large local reaction to one of the Hymenoptera stings do not warrant allergen skin testing beacause they are not at increased risk for future anaphylaxis.
• Generalized reaction warrants allergen skin testing.
• Large local reaction does not warrant allergen skin testing.
In many cases, skin testing should be delayed for at least 1 month after a sting-induced general reaction, beacase tests conducted closer to the time of the sting have a substantial risk of being falsely negative. Positive results on skin testing that correlate with the clinical history are sufficient evidence for considering Hymenoptera venom immunotherapy. If the patients are selected appropriately for skin testing, results of the test should not be ambiguous. However, random testing of the general population turns up positive results in patients without a history of anaphylaxis.
• Skin testing should be delayed for at least 1 month after a skin induced general reaction.
• People with clinical anaphylaxis and positive results on venom skin tests may benefit from venom immunotherapy.
Anaphylaxis is a generalized allergic reaction whose clinical hallmarks are flushing, hypotension and tachycardia. Urticaria and angioedema may occur in many cases, and in patients with moderate-to-severe asthma or rhitinis as a preexisting condition, the asthma and rhitinis can be made worse. This definition of anaphylaxis is based on its clinical phenomena. A cellular and molecular definition of anaphylaxis is "a generalized allergic reaction in which large quantities of both performed and newly synthesized mediators are released from activated basophils and mast cells." The dominant mediators of acute anaphylaxis are histamine and prostaglandine D2. The serum levels of tryptase may be increased for a few hours after clinical anaphylaxis. Physiologically, the hypotension of anaphylaxis is caused by peripheral vasodilatation and not by impaired cardiac contractility. Anaphylaxis is characterazid by a hyperdynamic state. Also, heparinemania may result from heparin release from mast cell granules (heparin provides a polyanionic comlex partner for polycationic histamine storage in mast cell granules); this further helps prevent vascular stasis and thrombosis due to low-flow states. For these reasons, anaphylaxis can be fatal in patients with preexisting fixed vascular obstructive disease in whom a decrease in proximal perfusion pressure leads to a critical reduction in flow (stroke) or in patients in whom laryngeal edema develops and completely occludes the airway.
• The clinical hallmarks of anaphylaxis are flushing, hypotension and tachycardia.
• Urtiaria and angioedema may be present.
• Histamine and prostaglandin D2 are the dominant mediators of acute and anaphylaxis.
• Peripheral vasodilatation causes hypotension of anaphylaxis.
Latex allergy is an important cause of intraoperative anaphylaxis. People with intraoperative anaphylaxis should be evaluated for possible latex allergy, usually by a skin test or in vitro assay. When patients with known latex allergy undergo invasive procedures, a latex-free environment is necessary. Patients with dermatitis, rhitinis, or asthma caused by latex allergy are at increased risk for anaphylaxis to latex.
• Latex allergy is an important cause of intraoperative anaphylaxis.
DO's And DON'T's For People With Hypersensitivity
• Avoid smelling a flower
• Avoid flowered prints for clothes
• Avoid cosmetics and fragrances, especially ones derived from flowering plants
• Never drink from a soft-drink can outdoors during the warm months; a yellow jacket can land on or in the can while you are not watching and go inside the can and sting the inside of your mouth (one of the most dangerous places for a sensitive person to be stung) when you take a drink
• Avoid doing outdoor maintenance and yard work
•Never reach a mailbox without first looking in it
• Never go barefoot
• Always look at the underside of picnic table benches and park benches before sitting down
• Never attempt physically to eject a stinging insect from the interior of an automobile but pull over, get out, and let someone else remove the insect.