Latex Allergy
The dramatic surge in the incidence of latex allergy in the 1980s is believed to be related to increased use of latex gloves after the adoption of universal precautions and to manufacturing changes that might have exposed health care workers and patients to latex gloves with higher latex content. Recognition of latex allergy as a public health concern led to identification of populations at risk, defined clinical symptoms, and recommendations for evaluation and management.1 In addition, guidelines for preventing new cases of latex allergy and for safety of latex-allergic patients were established.2 The major thrust of these policies is the restricted use of latex gloves, and the promotion of the use of nonpowdered sterile latex gloves to establish latex-safe environments in the hospital setting. Manufacturers of medical and commercial products have responded by labeling latex products and by developing latex-free items. These efforts to decrease latex exposure appear to have been successful in decreasing rates of sensitization and allergic reactions to latex.3
DEFINITION
Latex allergy is defined as the presence of specific immunoglobulin E (IgE) antibody to latex proteins in persons who have a variety of clinical symptoms to latex-containing products. The cause of latex allergy involves exposure and sensitization to the latex, which is derived from the sap of the rubber tree (Hevea brasilienses) and is harvested primarily in Malaysia, Indonesia, and Thailand.
PREVALENCE AND RISK FACTORS
Exposure to latex can occur by contact with skin, mucous membranes, or blood. Sensitization to latex proteins depends on the amount and duration of exposure and the predisposition to atopy, and it is defined as identification of specific IgE antibody to latex proteins, with or without clinical symptoms. Allergy is defined by sensitization and clinical symptoms. Prevalence rates of latex allergy or sensitization have varied from population to population. The highest rates are found in patients with spina bifida and other congenital urogenital anomalies (24%-60%), moderate rates are found in health care workers and employees in the rubber industry (5%-15%), and the lowest rates are found in the general population (1%).4 Irritant dermatitis may be another risk factor for the development of immunologic reactions to latex because the protective skin barrier is altered and allergen exposure and absorption may be increased, leading to possible IgE sensitization.
PATHOPHYSIOLOGY
Latex allergy is caused by latex allergens cross-linking specific IgE antibodies located on allergic effector cells, mast cells, and basophils. This action activates the cells to release preformed mediators, such as histamine, which cause immediate clinical symptoms of allergy, notably sneezing and itching. Activated mast cells also are responsible for the production of newly formed mediators (prostaglandins and leukotrienes) and cytokines (interleukin [IL]-4, IL-13, and tumor necrosis factor [TNF]-α), which contribute to more chronic symptoms of allergy such as nasal congestion and swelling of tissues. More severe clinical manifestations of latex allergy, such as anaphylaxis, are also related to the release of these allergic cell mediators and their effects on vasculature, leading to vasodilation and subsequently to hypotension.
SIGNS AND SYMPTOMS
Signs and symptoms of latex allergy depend on the type of latex product, the route of exposure, the amount of latex proteins, and the level of individual allergic sensitivity. Symptoms can vary from mild itching and urticaria, to rhinitis and asthma, to anaphylaxis. Latex gloves are probably the primary source of exposure, because they are used in many professions, including medicine, dentistry, housekeeping, daycare, and beauty and food services. This wide range of use can cause symptoms not only in persons wearing gloves but also in persons exposed to those wearing the gloves.
The most common adverse reactions experienced by persons wearing latex gloves are irritant reactions, typically erythema, cracking, dryness, and chapping of the skin. These reactions occur without an immunologic mechanism. Damage to the skin can occur by physical trauma with glove wearing, prolonged contact with solvents trapped underneath the gloves, extremes of skin temperature, and sweating.
Allergic contact dermatitis from latex gloves requires lymphocyte sensitization to chemical additives or accelerators that are used in the manufacturing process. The onset of symptoms is typically 24 to 48 hours after contact, and the symptoms are representative of contact dermatitis, including pruritus, erythema, blisters, or vesicles. Chronic symptoms include scaling, dryness, cracking, and thickening of the skin. Thiurams, carbamates, and benzothiazoles can be confirmed as allergens by patch testing.5
It is now known that latex allergens bind to cornstarch powder used in glove manufacturing and that significant levels of airborne latex proteins are found in medical and dental offices. Extensive studies performed at the Mayo Clinic demonstrate high levels of latex aeroallergens in operating rooms on days when many powdered latex gloves were used in the area, in contrast to minimal levels of airborne latex on weekend days and holidays when no gloves were used.6 This information has led to intervention policies to decrease levels of latex in operating rooms and hospitals.
Latex exposure to mucosal surfaces can be associated with systemic symptoms of hypotension, tachycardia, and bronchospasm, leading to anaphylaxis. Unfortunately, even limited mucosal exposure to latex has caused anaphylaxis; generalized reactions have occurred with toy balloons, urinary catheters, condoms, dental surgery, and rectal procedures.7
Another IgE-mediated reaction is the cross-reactivity between latex and several foods and fruits. Latex proteins share similar protein structures with other protective plant proteins found in fruits and foods. Latex-allergic persons have had oral symptoms of itching, swelling, and anaphylaxis with exposures to avocado, banana, and chestnuts. There have also been some reported reactions to potato, tomato, and kiwi.8 For this reason, latex-allergic patients should be questioned and informed about possible food reactions.
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