What is Latex Allergy

Latex allergy has become an important health concern in recent years, especially in the occupational setting for health care workers, such as nurses, doctors and allied health professionals. Latex barrier products are now in widespread use following the adoption of universal precautions for infection control, which has been associated with an increased number of people suffering from latex allergy. Latex allergy cannot be cured, however awareness of the problem and avoidance of latex for sensitised individuals remains the mainstay of treatment.

Natural rubber latex is derived from the sap of Hevea brasiliensis. It is the main constituent of over 40,000 medical and consumer products and is used in a wide variety of settings 7. Lists 1-3 detail some of the products that commonly contain latex.

List 1: Uses of natural rubber latex

# Latex concentrate (more likely to cause allergic reactions) Gloves (40%)
# Adhesives (16%)
# Thread (12%)
# Foam (12%)
# Carpets (7%)
# Imitation leather (7%)
# Other (6%) (includes condoms, medical products, babies teats and dummies)

Bulk (dry) natural rubber (less likely to cause allergic reactions)
# Tyres (70%)
# Latex goods (12%)
# Shoes (5%)
# Engineering (3%)
# Cables and tubes (2.5%)
# Vehicles (1.5%)
# Other (6%)

List 2: Common medical devices that may contain latex
Note that some of these products are now available in latex free alternatives.
# Bite blocks
# Blood pressure cuffs
# Bulb syringes
# Catheters*
# Dental coffer dams*
# Elastic bandages
# Electrode pads
# Endotracheal tubes and airways
# Enema syringes*
# Ventriculo-peritoneal shunts
# Finger cots
# IV access injection ports
# Manual resuscitators
# Penrose surgical drains
# Pulse oximeters
# Stethoscope tubing
# Stretcher mattresses
# Tourniquets
# Vascular stockings
* Reported as a cause of latex allergy

List 3: Common househould items that may contain latex
Note that some of these products are now available in latex free alternatives
# Adhesives
# Balloons*
# Carpet backing
# Condoms*
# Contraceptive diaphragms
# Elasticated fabrics*
# Feeding nipples
# Household gloves*
# Disposable nappies and incontinence pads
# Infant dummies (pacifiers) and teats for formula feeding
# Rubber bands
# Shoes
# Bandages
# Balls
# Erasers
# Hot water bottles
# Carpet backing
# Sports equipment
* Reported as a cause of latex allergy

In contrast to natural rubber latex, synthetic rubber latex is produced from petrochemicals and does not contain allergenic latex proteins. Products containing synthetic rubber latex (such as most latex paints, nitrile or neoprene gloves) do not cause allergic reactions.

Reactions to natural rubber latex can manifest in 3 different forms. The most severe and important form is an immediate Type-1 hypersensitivity reaction, which is covered here.

Other reactions to latex include:
# atopic dermatitis
“>Allergic Contact Dermatitis, which is a type-4 hypersensitivity reaction which results in eczematous lesions often associated with vesicle formation, after which the skin can become dry, crusted and thickened. Chemical additives such as accelerators and antioxidants are commonly implicated. A change to gloves which do not contain the implicated chemical, or use of cotton lining gloves for protection usually reduces the problem.
# Irritant dermatitis is a non-allergic skin rash characterised by redness, dryness, scaling, vesicle formation and cracking. These changes are caused by sweating or irritation of the glove with the powder residue, or from irritation from frequent washing, soaps and detergents.

Who gets Latex Allergy?

Less than 1% of the general population is allergic to latex, however certain people are at increased risk of developing latex allergy, including children with neural tube defects (such as spina bifida) or other congenital abnormalities requiring repeated surgery or catheterisation, and health care professionals who are exposed to latex in the workplace. The incidence of latex allergy is increasing along with the increasing frequency of allergies across the board.

Predisposing Factors

Most people with latex allergy have had frequent exposure to latex over a number of years. Most of these people are nurses, doctors, dentists or other health professionals who are exposed to latex in the workplace, or patients who have had multiple operations or other medical interventions (such as urinary catheterisations or diagnostic procedures), including children with spina bifida or other congenital defects such as renal abnormalities. People who are already allergic to other substances (for example, grass pollen or dust mite) are more likely to become allergic to latex.

Progression

Most people with latex allergy have been exposed to latex over several years. With the exception of gloves and balloons, most latex products in daily life do not contain enough allergen to cause significant problems.

Almost half of people with a latex allergy will also develop an allergy to certain fruits, most commonly avocado, banana or kiwi fruit. They will often get itching and/or swelling in the mouth and throat after eating these fruits.

Probable Outcomes

Latex allergy can get worse with increasing exposure to latex in some people, thus it is very important to try to limit exposure to latex in people who are allergic. However, many people will only ever experience mild reactions to latex.

How is Latex Allergy Diagnosed?

Diagnosis of latex allergy is largely made on clinical history. Some important aspects of the history include:
# Timing and duration of exposure to latex
# Relationship of latex exposure to onset of symptoms
# Types of symptoms including any suggestion of a generalised or systemic reaction
# Progression of symptoms over time
# Oral reactions to cross-reacting fruits such as banana, avocado, potato, tomato, chestnut and kiwi fruit
# Background history of atopic disorders such as asthma, eczema or allergic rhinitis

Allergy invesigations that are available include radioimmunosorbent testing (RAST), skin-prick testing and provocation tests, where exposure to latex is deliberate (such as wearing latex gloves). However, these investigations are usually not useful or necessary. The accuracy of both RAST and skin-prick testing is still controversial, and serious reactions have occurred with both skin-prick and provocation testing for latex allergy. Therefore the diagnosis of latex allergy is usually made on a good history.

How is Latex Allergy treated?

There is currently no curative treatment for latex allergy and desensitisation is still in the research phase, however it is showing promise. Therefore, avoidance of latex products is currently the best means of preventing serious reactions in patients allergic to latex.

In patients with a severe latex allergy, these measures should include:
# Provision of a Medic-Alert bracelet
# Use of latex-free gloves (particularly in the workplace)
# Specific measures to create a latex-free or minimised environment in health care settings where latex allergic patients will be treated
# Avoidance of areas where powdered latex gloves are used, as inhalational exposure to latex can lead to life-threatening reactions, and use of powdered gloves increases this risk.
# Preparation for inadvertent exposure to latex, including carrying antihistamines, corticosteroids and adrenaline (EpiPen) as appropriate)
# Carry a supply of latex free gloves for emergencies or procedures with a doctor or dentist
# Education to recognise allergic reactions to latex and what to do in the event of an allergic reaction
# Information about fruits that may cross-react to latex
# Education about products containing latex, including medical products and household products such as gloves, condoms, teats on bottles and dummies,
# Advise all health personnel including doctors and dentists of the allergy
# Avoid food prepared by personnel wearing latex gloves

Latex Allergy References

1. ASCIA Education Resources. Patient information bulletin: latex allergy. Australasian Society for Clinical Immunology and Allergy. 2004. Available at: http://www.allergy.org.au/aer/infobulletins/latex_allergy.htm
2. ASCIA Education Resources. Professional information bulletin: latex allergy. Australasian Society for Clinical Immunology and Allergy. 2004. Available at: http://www.allergy.org.au/aer/infobulletins/latex_allergy2.htm
3. ASCIA Position Paper. Latex Allergy. Australasian Society for Clinical Immunology and Allergy. 1998. Available at: http://www.allergy.org.au/pospapers/latex01.htm
4. Cullinan, P. Brown, R. Fieldz, A. et al. Latex allergy: A position paper of the British Society of Allergy and Clinical Immunology. Clin Exp Allergy 2003; 33:1484-99
5. Rolland, J. Drew, A. O’Hehir, R. Advances in development of hypoallergenic latex immunotherapy. Curr Opin Allergy Clin Immunol. 2005; 5:544-51.
6. Sussman, G. Beezhold, D. Allergy to latex rubber. Annals of Internal Medicine. 1995; 122: 43–46.
7. Taylor, J. Erkek, E. Latex allergy: diagnosis and management. Dermatologic Therapy. 2004; 17:289-301

What is Atopic dermatitis

Atopic dermatitis, or eczema, is a chronic skin disease in which the skin becomes red, dry, itchy or scaly and may weep, bleed and crust over. ‘Atopic’ is a term used to describe allergic conditions for which there is a family history , ‘dermatitis’ means inflammation of the skin.

Eczema is part of the ‘atopic triad’ of allergic conditions (also including asthma and hay fever) in which many sufferers experience all three conditions. It is the incessant itch of eczema that separates it from other skin diseases such as psoriasis.

The site of the disease depends on the age of the patient.

• In young children, the dermatitis typically occurs on the face, scalp, limbs, or body trunk. The nappy areas are usually spared.
• In older children and adolescents, the dermatitis is often accompanied by thickening and darkening of the skin, as well as scarring from repeated scratching. The sites involved are usually the extensor areas, ie the knee and elbow areas.
• In adults, the dermatitis most commonly affects the back of the neck, the elbow creases, and the backs of the knees (called the flexural areas). Other affected areas may include the face, wrists, and forearms.

Who gets Atopic dermatitis?

Eczema is becoming increasingly common. About 8 to 25% of people worldwide have eczema, compared to 4% in the 1940s. It often occurs in people who have other allergic disorders, such as asthma and hay fever. Eczema may occur at any age, however most often eczema begins in infancy and childhood. Eczema typically manifests in infants aged 1-6 months. Eczema equally affects males and females; however females generally have a worse prognosis.

Predisposing Factors

Eczema is caused by a complex interaction between genes and environmental triggers. Researchers have found that around two-thirds of eczema cases and a quarter of asthma cases involve mutations to a gene that helps form the skin’s outer protective layer. This outer layer is made up of dead cells that are collapsed together into a continuous protein sheath that keeps water in and invaders such as bacteria out. Filaggrin is one of the proteins that is very important in maintaining this protective barrier. Several studies have now demonstrated an association between mutations in the filaggrin gene and ezcema.

Environmental triggers that start off eczema have also been identified. Anything that could dry the skin may worsen atopic dermatitis. Potential triggers include:

* Skin infections
* Emotional stress
* Food or preservatives
* Pollens and dust mites
* Exposure to tobacco smoke
* Irritating clothes and chemicals (loose or poorly fitting clothing that constantly rubs the skin or contact with solvents, detergents, deodorants, cosmetics, and soaps)
* Excessively hot or cold climate or environment (hot showers or baths, overdressing, use of electric blankets or heating pads, and exposure to high humidity).
* Excessive bathing, hand washing, lip licking, sweating, or swimming.

Progression

The predominant symptom is intense itch. In children, sometimes itching can be so intense that the skin breaks after prolonged scratching. In this case sometimes infection leading to pus formation may occur.

Probable Outcomes

Most eczema patients improve; however, they need to understand that there is no cure for eczema. By following prevention strategies, the chances of exacerbations can be minimized. Eczema tends to fade with age. About 90% of eczema patients have spontaneous resolution by puberty.

How is Atopic dermatitis Diagnosed?

There is no specific test that diagnoses the presence of eczema. Diagnosis is usually based upon a person’s history and the signs noted during a physical examination.

How is Atopic dermatitis treated?

Because atopic dermatitis has no cure, the treatment aim is to to prevent outbreaks and to relieve discomfort by controlling the signs and symptoms if an outbreak occurs. Once eczema is diagnosed, a treatment plan will be made based on:

* Type and severity of the eczema present
* Age, health, and medical history (including presence of other conditions)
* History of previous eczema treatment

Since eczema is usually dry and itchy, most treatment plans involve applying lotions, creams, or ointments to keep the skin as moist as possible. The treatment plan also may require lifestyle modifications and using medication as directed.

Methods of treatment include:

1. Avoiding factors that worsen atopic dermatitis can effectively control the symptoms - this include avoiding exposure to solvents and detergents, managing emotional stress, avoiding rapid temperature changes, and anything that is found to worsen the condition.
2. Maintain skin hydration - Emollients are used to return moisture to the skin and often help relieve symptoms. They are most effective when applied after bathing.
3. Lukewarm baths can hydrate and cool the skin, temporarily relieving the itching of atopic dermatitis. However, hot or long (greater than 10 to 15 minutes) baths and showers should be avoided since they can cause excessive drying.
4. Topical steroid creams and ointments are often effective for controlling mild to moderate atopic dermatitis. Strong topical steroids can be used to control severe flares of atopic dermatitis; however long term use should be avoided due to the risk of serious side effects.
5. Other topical treatments for atopic dermatitis such as tacrolimus. They are particularly useful in sensitive areas such as the face and groin, and in children.
6. Taking steroids by mouth are occasionally used to treat a flare of chronic atopic dermatitis.
7. Oral antihistamines can be used to relieve the symptoms of itching and irritation of the eye that often occurs in conjunction with atopic dermatitis.
8. Ultraviolet light therapy (phototherapy) can effectively control atopic dermatitis. However this is reserved for patients not responding to other treatment methods as described above.
9. Immunosuppressive drugs can be used to control severe atopic dermatisis. However, these drugs do have serious side effects.

Atopic dermatitis References

1. eMedicine article. Krafchik, BR. Atopic Dermatitis [online]. 2005. [Cited 2005 October 6th]. Available at: URL: http://www.emedicine.com/DERM/topic38.htm
2. Williams HC. Is the prevalence of atopic dermatitis increasing? Clinical Experimental Dermatology 1992; 17, 6:385 - 91.
3. Eczema Association of Australiasia Inc. Membership Survey 2003.
4. Department of Dermatology, St Vincent’s Hospital Melbourne. Atopic Eczema Health Survey, January 1999 - February 2000, sample size 85.
5. Mar, A & Marks, R. The descriptive epidemiology of atopic dermatitis in the community, Australiasian Journal of Dermatology, 1999; 40:75-76.
6. Kay J, Gawkrodger DJ, Mortimer MJ, et al. The prevalence of childhood atopic eczema in a general population. J Am Acad Dermatol 1994; 30:35-39.
7. Palmer CN, Irvine AD, Terron-Kwiatkowski A et al. Common loss-of-function variants of the epidermal barrier protein filaggrin are a major predisposing factor for atopic dermatitis. Nat Genet 2006; 38:441-6.
8. Barker JN, Palmer CN, Zhao YW et al. Null mutations in the filaggrin gene (FLG) determine major susceptibility to early-onset atopic dermatitis that persists into adulthood. J Invest Dermatol 2007; 127:564-7.
9. Weller R & McLean WHI, Filaggrin and eczema. J R Coll Physicians Edinb 2008; 38:45-7.

Symptoms of This Disease:

* Allergy
* Skin Rashes

Drugs/Products Used in the Treatment of This Disease:

* Claratyne
(Loratadine)

* Phenergan
(Promethazine hydrochloride)

What is Spider Bite

Spider bites can affect anyone. It is a clinical entity typically exaggerated in movies and the media. Although spider bites can be common depending on the geographical distribution of different spiders, they are generally benign and harmless.

Spider bites can affect many sites. Generally reactions to spider bites can be divided into 3 types:

What is Insect Stings

Bee sting and wasp sting happen commonly, bee sting and wasp sting are one of the clinical encounters that are exaggerated and mystified in movies and medias. bee sting and wasp sting are mostly benign and harmless, but with massive bee and wasp sting they can be life-threatening. Also if anaphylaxis occurs, this can be from minimal stings and be life-threatening.

Insect stings can be due to the following:

bee sting

wasp sting

antsThe commonest would be stings due to insects from the Hymenoptera group. This group includes bees, vespids (wasps, yellow jackets, hornets), and ants.

Who gets Insect Stings?

Insect stings are extremely common. In the US, 9.3 million people are stung by ants each year. Other Hymenoptera sting accounts for more than 1 million stings annually.

Predisposing Factors

There is no racial predilection in Hymenoptera sting, and the bee and wasp sting affects all ages and genders. However reports indicated that men are affected by bee and wasp stings more than women, probably because of more frequent exposure rather than any biological differences.

Progression

The different types of reactions from insect bites and bee stings can be described as below:

# local reactions: after the insect bite or bee sting, the typical lesion is characterised by bee sting marking. Within minutes of the insect bite, local inflammation occurs, leading to local bright red tender nodule with subsequent hardening. Sometimes it can be accompanied by adjacent red plaques. The reaction of the insect bite often subsides in a few hours. As opposed to insect bites, bee & wasp stings are often painful, ranging from mild pain to severe, extreme pain. Not all local reactions subside quickly - for some individuals, large local reactions can occur with swelling that lasts from 48 hours to 1 week.# Toxic systemic reactions: this is due to venom injection through insect stings. This can be difficult to distinguish from systemic allergic reactions as the signs and symptoms are relatively similar.# Systemic allergic reactions: this happens through the typical type I hypersensitivity mechanism. Typical reactions include skin hives, angioedema and anaphylaxis reaction.

# Delayed reactions: this happens through type III hypersensitivity mechanism (see Introduction and type 3 hypersensitivity reaction). This can lead to a condition called serum sickness, and typically occurs days or weeks after the sting. With serum sickness, generalised inflammation of the different organ systems can occur, causing inflammation of the blood vessels, nerves, brain, kidneys, and clotting abnormalities.

Probable Outcomes

Although mystified in movies and media, bee stings and wasp stings are generally benign. Localised reactions are harmless. In Australia, the death rate due to wasp sting is at the figure of 0.02 deaths per million population per year. All deaths were attributable to anaphylaxis rather than envenomation.

Anaphylaxis is always life-threatening but it happens very rarely.

How is Insect Stings Diagnosed?

If the reactions to bee & wasp stings are severe enough, basic investigations may be done to rule out other medical conditions. These include looking at the blood function, liver function, kidney function and blood electrolytes……

How is Insect Stings treated?

Bee sting & wasp sting treatment is symptomatic. Below are the different treatment options depending on the types of sting reactions:

# local reactions: cleaning of the bee sting site, application of ice to bee sting site to reduce inflammation, and removal of the stinger with its venom sack to avoid continued injection of venom. Local symptoms such as itching and burning sensation can be treated with antihistamines (such as diphenhydramine, cetirizine). Sometimes steroids that can be applied locally are used (such as dexametasone, triamcinolone, etc) to reduce inflammation. Antibiotics can be used if infection develops.

# allergic bee sting reactions: this is treated as in any other type 1 hypersensitivity reaction, including ant-histamines, steroids for late phase reactions and adrenaline for life-threatening reactions like angioedema and anaphylaxis.

For massive bee sting attacks, acute treatment involves prompt removal of the stingers to reduce further envenomation. Treatment is entirely dependent on symptoms produced.

The mainstay of bee sting treatment is actually protective measures to prevent bee stings, especially if patients are known to have allergic reactions before. Insect repellents are not effective against stinging Hymenoptera. Avoidance is the best measure.

Insect Stings References

1. Antonicelli, L, Bilo, MB, Bonifazi, F. Epidemiology of hymenoptera allergy. Curr Opin Allergy Clin Immunol 2002; 2:341.
2. eMedicine: Bee and Hymenoptera Stings [online]. 2005. [Cited 2005 October 21st]. Available from: URL: http://www.emedicine.com/emerg/topic55.htm
3. McGain et al. Wasp sting mortality in Australia. MJA 2000; 173:198-200.
4. Reisman, RE. Insect stings. N Engl J Med 1994; 331:523.
5. Up to Date: Insect Stings [online]. 2005. [Cited 2005 October 21st]. Available from: URL: http://www.utdol.com/application/topic.asp?file=allergy/2070&type=A&selectedTitle=1~4
6. Valentine, MD. Anaphylaxis and stinging insect hypersensitivity. JAMA 1992; 268:2830.

What is Hives

Hives, or the medical term ‘Urticaria’ is a common allergic reaction on the skin. It is characterized by raised, red skin welts that are more than 5mm in diameter. Hives are extremely itchy, and often have a pale border surrounding the red area. The urticarial rash can be isolated or many, sometimes they join together and form a large area of raised, red rash.

Who gets Hives?

Urticaria is a common disease - it affects up to 25% of the general population.

Predisposing Factors

There is no specific predisposing factors for urticaria. Geographical regions do not have any influence on cases of urticaria. The number of cases are similar internationally.

Acute urticaria happens equally in men and women; but chronic urticaria seemed to be more common in women.

Urticaria happens in all ages, but chronic urticaria is more common in the 40-50s.

Progression

Urticaria is divided into 2 forms according to the duration of disease:

What is Angioedema

Angioedema is a reaction characterized by fluid accumulation leading to swelling (oedema) of the skin, mucosa and submucosal tissues. Sometimes this can extend to deeper tissues. Because of the rapid progression of the condition, it can lead to potential airway obstruction and suffocation. Hence, angioedema is treated as a medical emergency.

Angioedema is also known as angioneurotic oedema (older term). It can happen in different parts of the body, but the commonly affected part would be the face and the airways. Because of the swelling of the face, it can be extremely disfiguring and frightening to the patient.

Generally angioedema is characterised by involvement of the following sites:

• face
• airways, eg larynx (the voice box)
• bowels

Who gets Angioedema?

Angioedema is considered to be a rare condition. There are many triggers identified that can cause angioedema. Sometimes the ‘true’ incidence of angioedema is overlapped with anaphylaxis, as it can be a premonitory or accompanying symptom to an anaphylactic or anaphylactoid reaction.

Amongst all trigger for angioedema, angiotensin converting enzyme (ACE) inhibitor would be the most notorious. ACE inhibitors are drugs used to treat high blood pressure, for example enalapril, perindopril, etc. Angioedema occurs in 0.1-0.7% of patients taking the medication. Although uncommon, because of the large number of patients treated with this class of drugs, this can become a significant cause of angioedema.

Predisposing Factors

There are 2 types of angioedema - hereditary and acquired. Hereditary means having the disease from birth due to genetic defect; while acquired means the disease is caused by external substances. Hereditary angioedema is transmitted from parents to children. All races are affected equally, and both males and females are equally affected too.

As for acquired angioedema, it is presumed to affect all races where both males and females are affected equally.

However, hereditary angioedema usually occur earlier in the 20s, while acquired angioedema commonly occurs after the 40s.

Progression

Angioedema is a type I hypersensitivity reaction. Type I hypersensitivity is characterized by Ig E mediated reaction. Ig E is a specific type of antibody that helps to fight infection, but also responsible for this type of allergic response.

There are certain drugs that are associated with angioedema:
# Angiotensin-converting enzyme (ACE) inhibitors: to control high blood pressure
# Nonsteroidal anti-inflammatory drugs (NSAIDs): commonly used as pain-killer
# Radiocontrast agents: this are used in CT scans
# Opiates: this include morphine, oxycodone and generally used as strong pain-killers
# Aspirin: commonly used as pain relief

There are other common antigens causing angioedema:
# insect stings
# food such as fish, nuts, eggs, milk, chocolate, etc
# after infection
# animal protein

Angioedema usually progresses from minutes to hours, as typically occurs in type I hypersensitivity.

Probable Outcomes

Angioedema can be life-threatening if the upper airway (especially larynx) is involved due to lack of oxygen getting into the lungs. However most of the cases usually resolve very quickly with proper treatment. Given emergency treatment, angioedema can be effectively controlled.

How is Angioedema Diagnosed?

The diagnosis of angioedema is based on the signs and symptoms of the patient, and the history of exposure to allergens, and therefore does not rely on laboratory testing.

How is Angioedema treated?

Angioedema should be treated as an emergency because of potential airway compromise that can occur rapidly. Hence the basic approach would be:
# assessing the airway
# checking for breathing
# checking for circulation

Resuscitation of angioedema include looking at the airway structures, such as uvula, tongue, soft palate or larynx (voice box). If there are any signs of airway obstruction or severe drop in blood pressure, a drug called adrenaline will be given through the veins. The dose is usually adjusted to the body’s response.

After initial resuscitation, antihistamines and/or steroids can be administered to control the symptoms. They serve as long-acting medications.

It is important to remember the offending agent and avoid it in the future, if possible.

Angioedema References

1. Cotran, Kumar, Collins. Robbins Pathologic Basis of Disease. 6th ed. WB Saunders Company. New York. 1999.
2. eMedicine: Angioedema [online]. 2005. [Cited 2005 October 11th]. Available from: URL: http://www.emedicine.com/ped/topic101.htm
3. eMedicine: Angioedema [online]. 2005. [Cited 2005 October 11th]. Available from: URL: http://www.emedicine.com/med/topic135.htm
4. fUp to Date: Angioedema [online]. 2005. [Cited 2005 October 11th]. Available from: URL: http://www.utdol.com/application/topic/print.asp?file=allergy/11363&type=A&selectedTitle=1~26

What is Anaphylaxis

Anaphylaxis is a sudden, severe allergic reaction to a substance (called an allergen) that can be life-threatening. Common substances which can cause as severe allergic reaction include bee stings, insect bites, peanuts, eggs, drugs given to the body, etc. Anaphylaxis suddenly affects the whole body, with severe allergic symptoms including: difficulty breathing, rash, swelling, tummy pain, and reduced blood pressure leading to shock. Anaphylaxis is a medical emergency where immediate treatment is needed to prevent potential death.

When exposed to a foreign substance, some people suffer reactions identical to anaphylaxis, but in which no allergy is involved. These reactions are called anaphylactoid, meaning anaphylaxis-like reactions. In anaphylaxis, the immune system must be “primed” by previous allergen exposure. But in anaphylactoid reactions can occur with no previous allergen exposure at all. An example of something that can bring on a severe allergic reaction is radiographic contrast material (the dye injected into arteries and veins to make them show up on an x-ray).

Although the mechanism of an anaphylactoid reaction is different. The allergy treatment is the same.

Who gets Anaphylaxis?

Anaphylaxis occurs infrequently. However, it is life-threatening and can occur at any time. Milder forms of anaphylaxis occur much more frequently than fatal anaphylaxis.

The frequency of anaphylaxis is increasing and this has been attributed to the increasing number of potential allergens to which people are exposed.

In the US, anaphylaxis causes approximately 500-1000 deaths in a year. However the figure is difficult to determine accurately because of underdiagnosis and underreporting.

No major differences have been reported in the incidence and prevalence of severe allergic reactions between men and women.

Anaphylaxis occurs in all age groups. While prior exposure to allergens is essential for the development of true anaphylaxis, severe allergic reactions occur even when no documented prior exposure exists. Thus, patients may react to a first exposure to an antibiotic or insect sting. Adults are exposed to more potential allergens than are pediatric patients. The elderly have the greatest risk of mortality from severe allergic reactions due to the presence of other diseases usually suffered by elderly population.

Predisposing Factors

The likelihood of an individual having anaphylaxis is influenced by the following:
# age
# gender
# atopy (genetic tendency to develop classic allergic diseases)
# route of exposure
# history of prior exposure
# history of prior anaphylactic episodes

Other risks include prior history of any type of allergic reaction. After an initial exposure to a substance like bee sting toxin, the person’s immune system becomes sensitized to that allergen. On a subsequent exposure, an allergic reaction occurs.

Severe allergic reactions are usually triggered by a limited number of allergic exposures. These include injection, swallowing, inhaling or skin contact with an allergen by a severely allergic individual.

Examples of injected allergens are bee, hornet, wasp and yellow jacket stings; certain vaccines which have been prepared on an egg medium; and allergen extracts used for diagnosis and treatment of allergic conditions. Antibiotics such as penicillin can trigger a reaction by injection or swallowing.

Typically, a severe reaction caused by a food allergy occurs after eating that particular food, even a small bite. Allergy to peanuts is an example. Skin contact with the food rarely causes anaphylaxis. Foods most commonly associated with anaphylaxis are peanuts, seafood, nuts and, in children particularly, eggs and cow’s milk.

A severe allergic reaction from an inhaled allergen is rare. An increasingly recognizable example is when an allergic individual inhales particles from rubber gloves or other latex products.

Progression

The signs and symptoms of anaphylaxis may occur almost immediately after exposure or within the first 20 minutes after exposure. Rapid onset and development of potentially life threatening symptoms are characteristic markers of anaphylaxis.

Allergic symptoms
may initially appear mild or moderate but can progress rapidly. The most dangerous allergic reactions involve the lungs and/or heart/vessel system.

Probable Outcomes

Anaphylaxis is a severe disorder which has a poor prognosis without prompt treatment.

Symptoms, however, usually resolve with appropriate treatment, therefore highlighting the importance of immediate action. There are no long-term effects of anaphylaxis other than the possibility of recurrence or the occurrence of this disease.

How is Anaphylaxis Diagnosed?

The diagnosis of anaphylaxis is based on the signs and symptoms of the patient, and the history of exposure to allergens, and therefore does not rely on laboratory testing.

How is Anaphylaxis treated?

Immediate management:

Anaphylaxis is an emergency condition requiring immediate professional medical attention. Assessment of the ABC’s (Airway, Breathing, and Circulation) should be done in all suspected anaphylactic reactions.

Adrenaline is a drug that should be given by injection without delay. This opens the airways and raises the blood pressure by constricting the blood vessels. Adrenaline comes in multiple formats, one of them called Epi-pen that might be carried by individuals.

CPR (cardiopulmonary resuscitation) should be initiated if needed. People with known severe allergic reactions may carry an Epi-Pen or other allergy kit, and should be assisted if necessary. Emergency interventions by paramedics or physicians may include placing a tube through the nose or mouth into the airway (endotracheal intubation) or emergency surgery to place a tube directly into the trachea (tracheostomy or cricothyrotomy).

Treatment for shock includes giving fluids into the patient through the veins and medications that support the actions of the heart and circulatory system.

Antihistamines and steroids may be given to further reduce symptoms (after lifesaving measures and adrenaline are administered).

Prevention of anaphylaxis:

Prevention involves avoidance of known allergens. Any person experiencing an allergic reaction should be monitored, although monitoring may be done at home in mild cases.

Occasionally, people who have a history of drug allergies may safely be given the offending medication after pretreatment with corticosteroids (prednisone) and antihistamines (diphenhydramine).

People who have a history of allergy to insect bites/stings should be instructed to carry (and use) an emergency kit consisting of injectable adrenaline and chewable antihistamine. They should also wear a Medic-Alert or similar bracelet/necklace stating their allergy.

Anaphylaxis References

1. Anaphylaxis Action Plan - generic - Australian version [online]. 2005. [Cited 2005 October 6th]. Available from: URL: http://www.allergy.org.au/aer/infobulletins/posters/Anaphylaxis_plan_(gen)_Au.pdf
2. eMedicine: Anaphylaxis [online]. 2005. [Cited 2005 October 6th]. Available from: URL: http://www.emedicine.com/EMERG/topic25.htm
3. Pumphrey, R. Anaphylaxis: can we tell who is at risk of a fatal reaction?. Curr Opin Allergy Clin Immunol 2004; 4:285.
4. Sampson, HA, Munoz-Furlong, A, Bock, SA, et al. Symposium on the definition and management of anaphylaxis: summary report. J Allergy Clin Immunol 2005; 115:584.
5. Up to Date: Anaphylaxis [online]. 2005. [Cited 2005 October 6th]. Available from: URL: http://www.utdol.com/application/topic.asp file=cc_medi/5448&type=A&selectedTitle=1~59

Symptoms of This Disease:

* Allergy
* Skin Rashes

Drugs/Products Used in the Treatment of This Disease:

* Adrenaline Injection
(Adrenaline acid tartrate)

* Albay Bee/Wasp/Yellow Jacket Venom
(Allergen extracts)

* Allergenic Aqueous Extracts
(Allergen extracts)

* Allergenic Extracts for Scratch & Prick Testing

* Allpyral Allergen Extracts
(Allergen extracts)

* EpiPen
(Adrenaline)

* Phenergan Injection
(Promethazine hydrochloride)

* Promethazine Hydrochloride Injection BP (DBL)
(Promethazine hydrochloride)

Diseases

What is Allergic Disease

3D Animation

Allergies occur when the immune system reacts against harmless substances in the environment. The immune system is extremely complex and so there are many opportunities for things to go wrong. When the immune system begins to react against harmless substances in the environment, this can lead to allergic reactions, which are exaggerated, damaging immune responses to substances that are normally harmless.

When people with allergy diseases are exposed to common environmental substances such as house dust mite or grass pollens, a type of white blood cell (B lymphocytes) produce specific antibodies known as IgE against that substance. This IgE then attaches itself to another type of white blood cell (mast cells), and when the mast cells come into contact with that substance again, they initiate a complex immune response that leads to the allergy.

Different people with allergies are allergic to different substances. Some of the substances that people are commonly allergic to include:

* House dust mite
* Pollens from grasses and trees
* Animal dander including cat, dog, horse
* Moulds
* Foods including tree nuts, peanuts, shellfish, fish, milk, eggs, wheat and more
* Latex

Different people with allergies also react differently when they are exposed to the substance they are allergic to. Some common reactions include:

* Allergic eczema or urticaria
* Allergic rhinitis (hayfever)
* Allergic asthma
* Anaphylaxis

For more health information on allergies, visit Anatomy and Physiology of Allergy

Who gets Allergic Disease?

Approximately 20% of the general population is defined as atopic, where they have a tendency to be allergic. These people will have a positive reaction to skin prick tests or RAST tests, but they may or may not suffer from any symptoms. Approximately two-thirds of atopic individuals will have clinical allergic disease, or allergic reactions to the substance that they are allergic to.

Predisposing Factors

The tendency to have allergic reactions, or atopy, is inherited. If you have 2 parents who are atopic (have a positive skin prick test), your risk of being atopic is 75%. The risk goes down to 50% if you have 1 atopic parent, and to 15% if neither of your parents are atopic.

Environmental factors also have a role in determining whether or not a person becomes atopic, and research is continuing to determine whether there is anything that can be done to prevent a person from become atopic.

Research is also continuing to determine why some people who are atopic develop allergic reactions while other people who are atopic remain asymptomatic (do not have any symptoms of allergic reactions).

Progression

There are several steps in the development of an allergic reaction.

1. Sensitisation

Previous exposure to a substance results in B lymphocytes making specific IgE against that substance. The IgE then attaches to receptors on mast cells in the blood stream.
2. Activation of mast cells

When the substance again comes in contact with IgE on the mast cell (such as when the allergen is inhaled), the mast cell releases histamine and other mediators (including serotonin and leukotrienes).
3. Effects of histamine and other mediators

When these mediators are released, they lead to the symptoms of allergic diseases.

Probable Outcomes

The tendency to develop allergic reactions is usually lifelong, however the manifestations and symptoms can change over time. Children often go through a sequence of allergic diseases, developing allergic eczema in early infancy, followed by allergic rhinitis and allergic asthma, usually by 5 years of age.

Different people experience different types of reactions which may change over time, and may improve or get worse depending on a number of factors, which can include where they live and their environment.

How is Allergic Disease Diagnosed?

There are several investigations that can be useful in patients with allergic disease:

Blood Tests:

* Total serum IgE levels are elevated in the majority of patients with allergic disease.
* Serum eosinophilia is often observed in patients with allergic disease.

These blood tests are not diagnostic, but they can be useful to determine the severity of the allergic tendency.

Tests to determine allergies:

* Skin prick tests against a wide variety of allergens are highly sensitive and are the first line test to determine what allergens a patient is allergic to.
* Radioallergosorbent tests (RAST) detect serum levels of allergen-specific IgE. It is used when the history and skin prick test results are conflicting, when skin prick testing cannot be performed, or when desensitisation is being considered.

How is Allergic Disease treated?

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Specific allergy treatments are often tailored to the specific allergic disease, particularly eczema, allergic rhinitis and asthma. There are, however, some general treatment principles:

Allergen avoidance

* Avoiding areas where allergens are in high concentration (e.g. the park in springtime where heyfever causing pollens are in high concentration, or avoiding cats or dogs)
* Reducing exposure to allergen (e.g. reducing exposure to house dust mite allergen by encasing mattresses and bedding in dust mite protectors, regular vacuuming)

Allergy medications

* Anti-inflammatory medications designed to reduce the overzealous immune responses seen in allergic disease, such as topical corticosteroids (inhaled, intranasal, skin creams) have a role in eczema, allergic rhinitis and asthma.
* Antihistamines have a role in eczema and hayfever, but not in asthma.
* Adrenaline has a role in severe allergic reactions such as anaphylaxis.

Allergy desensitisation:

* Desensitisation is not suitable for all allergic diseases. It is particularly useful for insect stings and drug allergies, where it is usually effective, but less useful for asthma or allergic rhinitis, where it is less effective. It is most useful where there are a small number of allergies, such as only insect stings, and less useful when there are multiple allergies.

For more health information on allergy treatment visit your local doctor.

Allergic Disease References

1. Gold M, Kemp A. Atopic disease in childhood. MJA. 2005; 182(6): 298-304.
2. Peakman, M. Vergani, D. Basic and Clinical Immunology. 1997. Churchill Livingstone. New York.
3. Solomon, E. Berg, L. Martin, D. Biology. 5th ed. 1999. Saunders College Publishing. Fort Worth.
4. Warrell, D. Cox, T. Firth, J. Benz, E. Oxford Textbook of Medicine. 4th ed. 2003. Oxford University Press. Oxford.