Allergic Reactions to Latex

Latex

Latex that is used commercially is derived from the rubber tree (Hevea brasiliensis), one of the many worldwide lactifer plants, which include Ponsettia (Euphorbia pulcherrima) and Castor Bean (Ricinus communis). Lactifer plants are unique in that they contain cells that secrete a milky substance - latex. Latex circulates in branched tubes throughout the plant tissues and forms a plug that can heal cuts in the surface of the plant, similar to the way a blood clot occurs in a human wound.

Latex allergens

Approximately 12% of harvested latex is treated either with ammonia alone (high ammoniated latex) or with ammonia and thiuram (low ammoniated latex) and used in the production of "dipped" products such as condoms, balloons and gloves. Contact with these items accounts for the majority of reactions to latex. Most of the harvested latex is acid-coagulated and then "vulcanised" by treatment with sulfur at extremely high temperatures for prolonged periods of time, resulting in low-to-undetectable levels of allergenic proteins. This explains why reactions do not occur in latex-allergic patients driving on or walking by roads, where levels of latex particles are high. There are at least 11 different latex proteins, six of which are considered to be of major importance in the development of allergic reactions.

Allergic and non-allergic hypersensitivity

Reactions to latex can be caused by either allergic or non-allergic hypersensitivity:

Non-allergic hypersensitivity

Irritant Contact Dermatitis (ICD) (see Contact Dermatitis): This irrititant reaction is the most common clinical reaction to latex products. Dry, itchy, irritated patches occur on the skin, usually of the hands, associated with heavy use of latex gloves. The sweating caused by wearing gloves may be sufficient to cause a reaction, but other factors include frequent hand washing, incomplete drying of the hands, and the use of cleansing products and disinfectants. Cornstarch glove donning powder is an additional irritating factor because it produces an alkaline pH of the skin.

Allergic (delayed) hypersensitivity

Allergic Contact Dermatitis (ACD) (see Contact Dermatitis): This is a delayed allergic reaction, not involving IgE-antibodies. This allergic hypersensitivity reaction is caused by the chemicals, particularly rubber accelerators, that are added to raw latex during harvesting, processing and manufacturing. Upon re-exposure, individuals who are already hypersensitive to these chemicals develop red, raised, blistering patches of contact dermatitis within 48-72 hours. The patches are usually confined to the area of contact but may spread more extensively.

Latex Protein (immediate) Allergy: This is an immediate allergic reaction caused by IgE-antibodies to latex, which develops in minutes after contact with latex by those who have developed IgE-sensitization to latex proteins. True latex protein allergy is uncommon, and mainly affects individuals who have to undergo repeated medical procedures, such as spina bifida patients. Symptoms can include:

• Contact urticaria - either localized to the area in contact with the latex, or sometimes more widespread.
• Rhinosinusitis and conjunctivitis.
• Asthma.
• Anaphylaxis - rarely

Persistent contact with latex in a latex protein sensitized individual can cause long-term symptoms of the skin, eyes and respiratory tract. (See the modules in this series - rhinosinusitis, ocular allergy, urticaria, contact dermatitis and anaphylaxis.)

Prevalence

An increase in the incidence of latex protein allergy occurred in the late 1980s, most probably as a result of two factors:

• The recommendations for prevention of HIV transmission in health care settings, which are commonly referred to as "universal precautions." These rules and regulations mandated that health care professionals use barrier protection, including latex gloves, to protect against transmission of infectious organisms.
• Implementation of "universal precautions" then caused a dramatic increase in the manufacturing of latex gloves, with changes in the way the latex was processed; this processing resulted in an increase in the amount of latex protein retained in latex products.
  

Approximately 50% of all cases of latex protein allergy have been reported in health care professionals, and it is likely that the high incidence in this group of workers is a direct result of the frequent contact with latex at work. IgE-sensitization to latex has an equal prevalence in healthcare professionals and in the general population.

Development of latex protein allergy

Latex proteins can cause IgE-sensitization in the following ways:

• Inhalation of powder particles to which latex protein allergens have been absorbed, when latex gloves are put on or taken off.
• Absorption through the skin from latex products, particularly when the skin is damaged by trauma, irritation, or contact dermatitis.
• Absorption through mucous membranes from condoms, or from latex items used in surgical procedures. The allergenic latex protein content varies widely among various latex-containing medical devices, and even between different batches of the same medical products.
• Direct entry into the body during surgical procedures, either from medical devices, or when the physician and/or other healthcare professional is using latex gloves.

Symptoms

Symptoms of latex protein allergy are more likely to occur in the following groups:

• Healthcare professionals and individuals who work in rubber manufacturing and processing, food preparation, cleaning, gardening and housekeeping.
• Infants and children undergoing multiple surgical procedures.
• Children with severe allergic eczema.
• Individuals with fruit allergy (mostly banana, melon, kiwi and peach).
• Patients undergoing multiple dental, radiological or gynecological procedures.
• Individuals who use condoms.
  

The symptoms of latex protein allergy depend upon the affected organ. (See the modules in this series - allergic rhinitis, allergic conjunctivitis, urticaria, contact dermatitis and anaphylaxis.)

Diagnosis

Skin testing

A safe and approved skin prick testing solution for latex protein allergens is not available universally, but safe, reliable testing solutions are available in specialized centers.

Blood tests

Blood tests to detect specific IgE antibodies to latex are available.

Some people with a clinical history suggestive of latex protein allergy can have negative skin prick test or blood test results. This may be because their latex allergy is not caused by an IgE-mediated reaction to latex, or because the testing solution does not contain the latex protein/s to which the individual is sensitized.

Cross-reactivity of latex allergens

Studies of skin prick testing of latex protein sensitized subjects have showed 53% to have positive tests to avocado, 40% to potato, 38% to banana, 28% to tomato, 28% to chestnut and 17% to kiwi. This "cross-reactivity" among fruits, pollens and latex is attributable to some degree to the plant allergen, profilin, which is present in all three.

Most patients who have IgE antibodies to these foods do not have allergic symptoms, so a positive skin test does not necessarily mean the food cannot be eaten. Those who have allergic reactions to fruit and vegetables develop the "oral allergy syndrome" and experience itching of the mouth and throat when eating the fruit or vegetable; rarely, angioedema of the face may also occur. Patients clinically allergic to foods which are cross-reactive to latex should ideally be screened for individual risk for latex allergy with an appropriate history, physical examination and a skin test (if available) and a blood test to identify IgE antibodies to latex.

Management

Repeated exposure to latex in latex-sensitized patients may lead to life threatening symptoms. The medical management of latex protein allergy is to avoid skin or mucous membrane (e.g., inside the mouth, nose, vagina or rectum) contact with latex proteins.

1. Reduction in exposure to latex proteins in the workplace:

• Where possible, latex gloves should be replaced with non-latex gloves, although latex gloves remain the best barrier against infectious organisms.
• Latex gloves should be powder free and contain a low latex protein content.
  

These measures should help to reduce the overall prevalence of latex allergy.

2. Reduction to exposure to latex proteins in the home:

If an individual has a history of non-life-threatening reactions to latex, e.g., contact urticaria, mild asthma, rhinitis or conjunctivitis, take a realistic and practical approach to latex avoidance; excessive latex avoidance is unnecessary, financially costly, and impacts on lifestyle. If there is a history of life-threatening reactions to latex, e.g., severe asthma, angioedema or anaphylaxis, closer vigilance is necessary. The most important products to avoid are latex gloves (either worn by the individual, or used during surgery), latex condoms, and latex-containing medical products such as catheters, and avoid blowing up latex balloons. Household items, clothing, and sports equipment containing latex are more likely to affect people who experience contact dermatitis if they come into contact with latex.

Where necessary, the following latex products can be replaced non-latex products:

It is important to stress that because of the way the latex is processed, many forms of rubber are not dangerous to latex allergic individuals, for example, rubber soles, basketballs, latex in tires, and many other products.

Managing the patient with latex protein allergy:

Patients with latex protein allergy should:

1. Wear a medic alert bracelet or necklace, especially if the allergy is severe and life threatening.
2. Inform parents and family, employers, school personnel, care givers and healthcare professionals about their latex protein allergy, and ensure that latex protein allergy is noted prominently on all medical records.
3. Be given a list of latex-containing products most likely to cause a reaction and use safe alternatives.
4. If prescribed by the physician, carry an epinephrine auto-injector at all times.
   

Medical sources of latex may include the following items. Where necessary, avoid the following:

• Gloves
• Blood pressure cuffs
• Catheters
• Dental devices
• Face masks and straps
• Tourniquets
• Wound drains
• Injection ports
• Electrode pads
• Bulb syringes
• Bandages
• Rubber in syringe stoppers
• Stethoscope tubing

Communicate latex precautions to healthcare professionals:

1. Alert healthcare professionals to the potential for latex protein allergy.
2. Printed precautions and alternatives should be in place to care for latex protein allergic subjects.
3. Latex protein allergy should be noted on the patient's chart/notes.
4. A medical alert bracelet or necklace is useful for the severe allergic subject.
5. Appropriate caution should be taken by physicians and other healthcare professionals in clinical settings.
6. Health care professionals who use latex gloves should wash carefully and change their outer garments before they treat the highly latex protein allergic patient.

Glossary of terms

Allergic (delayed) hypersensitivity: A delayed allergic reaction involving lymphyocyte cells; not involving IgE antibodies

Latex protein allergy: An immediate allergic reaction involving IgE antibodies

Non-allergic hypersensitivity: An irritant reaction; not involving IgE antibodies

IgE-sensitization to latex: The presence in the body of specific IgE antibodies against latex protein

Specific IgE: An antibody produced in response to first contact with a sensitizing protein

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