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Latex Allergy Latex sensitivity is an immunologic response to either the protein in the latex or the chemicals used in the production of latex products. The water soluble protein is found in the milky sap obtained from the “Hevea brasiliensis” rubber tree. This sap is used in such products as rubber gloves, condoms, balloons, rubber bands, urinal bags, glue for reclosable envelopes (to name a few). There are three categories of allergic reactions to latex:
After appropriate testing has shown a positive allergic response to latex, the offending allergen should be totally eliminated from your environment. In November, 1992, the Food and Drug Administration and the Centers for Disease Control met with latex manufacturers in Washington in an effort to begin to identify which of the 50 or 60 different proteins in latex may provoke the allergic response, and to determine how the manufacturing process might be altered to minimize risk to consumers. In the meantime, there are alternatives. “Sensicare” synthetic latex gloves are as durable as latex, but much more expensive. “Tactylon”, a non-latex, non-vinyl material that is said to be as elastic as latex, is also more costly. “Nitrile” gloves are non-latex and non-vinyl gloves, which are much more affordable. Note: The following foods cross-react with latex: Banana, avocado, chestnut and kiwi. This means that if you are allergic to one, you are at great risk of being allergic to the others.
Latex Allergy - by Jay Weiss, Ph.D Introduction Latex allergy is a significant and increasingly recognized phenomenon. The American Academy of Allergy and Immunology, the Food and Drug Administration (FDA), and the rubber industry have all voiced concern about the rise in IgE-mediated latex allergy. Conferences devoted to latex allergy alone have been held in the US, Europe and Malaysia. Numerous medical meetings have also included individual symposia on the topic. Latex allergy is very serious because it can cause life-threatening reactions during surgery and standard medical procedures such as barium enema administration. Many anaphylactic cases have been attributed to latex, and recognition of latex allergy is an important part of evaluating patients for procedures during which latex exposure will occur. The first reports of sensitivity to latex were delayed Type IV, cutaneous reactions. The most common antigens causing Type IV reactions were identified as accelerants and antioxidants used in the manufacturing process. In 1979, when Nutter1 reported urticaria to latex, the rubber material itself was suspected as the cause of Type I hypersensitivity. Type I, IgE-mediated latex allergy has since become a recognized affliction. Latex skin-testing and serological testing have demonstrated the presence of allergen-specific IgE. The general consensus is that most allergens are natural proteinaceous products of the rubber tree, Hevea brasiliensis. Rise in Latex Allergy Incidence Concerns about latex allergy increased greatly in 1988 when several deaths occurred during barium enema administration due to exposure to latex in enema cuffs; the enema cuffs were recalled. The FDA issued an alert to all health care workers and set up a problem-reporting program. In the period from October 1988 through September 1992, 1118 adverse reactions to latex were reported, including 15 deaths from enema cuff exposure.2 (See Figures 1 and 2). The incidence of latex allergy rose sharply when universal precautions were instituted. Debate continues about the cause of this increase, but several factors seem to be involved. Universal precautions have been responsible for increased exposure to latex among both health care workers and patients. The increased demand for latex gloves led to a change in the quality of some gloves, which may have contained more allergen, consequently causing sensitization. In addition, the time from tree to a dipped latex product became much shorter, which may have allowed more allergen to be incorporated into products. Just as important, the diagnostic acumen to recognize latex allergy has improved. Individuals at Risk Three populations at high risk of being sensitized to latex are children with myelomeningocle; health care workers; and rubber industry workers, who are exposed for prolonged periods and to high doses of latex. Children with spina bifida have been studied most frequently. The prevalence of latex sensitivity has been found to range from 34 to 100%.3-7 Prevalence figures for spina bifida patients have been based on two different methods for detecting latex-specific IgE. In studies using solid-phase technologies, the prevalence of latex allergy was found to be 34 to 39%. When similar patients were skin-tested for specific IgE, the prevalence was found to be 50 to 100%. The low sensitivity observed with solid-phase technologies has been reported by several investigators.8-10 Health Care workers (including surgeons, nurses, operating and laboratory personnel, and lab technicians) reportedly have latex-specific IgE prevalences ranging from 4.5 to 14.4%.11-14 In a study of occupational allergy due to latex,15 one surgical glove manufacturing plant had several workers who developed occupational asthma that was attributed to latex. When all the workers were tested, 11% were found to be reactive. This prevalence of sensitization is similar to that observed in health care workers. Studies in other populations have been conducted. One study determined the prevalence of latex sensitization in nonhealth care workers to be 0.8% using skin-testing.11 In a study using DPC’s AlaSTAT test for latex specific IgE in a nonhealth care, blood donor population, 6.5% of the donors were found to have latex-specific IgE.16 A study of atopic children found that 3.8% were sensitized to latex.17 The high prevalence of latex sensitization in a wide range of populations indicates that this allergy is a potentially severe health hazard. Latex Source and Uses Latex is the name for the milky sap collected from the rubber tree, Hevea brasiliensis. Rubber trees are cultivated for this sap, which is processed into many types of products. (See Table 1.) The liquid latex (“natural rubber latex”) is used to produce dipped products like gloves, condoms and balloons. It can also be dried and used to create products such as syringe plungers, vial stoppers and baby nipples. The desirable physical properties of natural rubber latex have been reproduced with synthetic latex only at markedly increased cost. Allergenic Components of Latex Latex, like most natural products, is a complex mixture of many components. It consists mainly of cis-1,4-polyisoprene, with small amounts of proteins, carbohydrates and lipids. The protein content of raw latex is approximately 2 to 3%. In finished latex products such as gloves and condoms, the protein content has been found to range from less than 0.05 to 1 mg of extractable protein per gram of latex, or approximately 0.1% or less by weight. Some of the proteins are integral to latex and are necessary for the formation of dipped latex products. Two such proteins are rubber transferase and the rubber elongation factor protein. Not all latex proteins are allergens. Whereas the protein content of a product may be an important factor in monitoring production, the allergen content is more important in determining whether sensitive individuals will react to it. Latex allergens have been identified by several investigators. The common detection method is immunoblotting with sera from clinically reactive patients. Using this method, allergens have been characterized by molecular weight as determined in SDS-PAGE system. Latex allergens have been reported to range in molecular weight from 2 to 90 kilodaltons (kD). Frequently reported allergens have molecular weights of 14 to 15 kD, and 29 to 34 kD.18-20 Because latex is processed from its natural form, it is plausible that new antigens (neo-antigens) could be formed during the processing. One investigator has detected an allergen in an extract from gloves that was not present in raw natural rubber latex. Unfortunately, as manufacturing processes change, allergens isolated from finished latex products also change, and therefore are not consistent, reliable sources of latex allergen for testing patients. Many investigators have found that raw natural rubber latex, which is collected without ammonia, is the most consistent source of relevant latex allergens. Additives may constitute another source of allergens in manufactured products. In one instance, casein, a protein added during latex processing, was reported as the cause of glove allergy.21
Table 1: Commonly used products containing natural rubber latex or dry
rubber latex
Crossreactive Food Allergens Latex sensitivity has been correlated with food allergy. The presence of latex-cross-reactive epitopes has been established in banana, avocado, and chestnut. Clinical sensitivity to these cross-reactive food allergens is also associated with signs and symptoms such as oral itching when eating cross-reactive foods are recognized risk factors for latex allergy. Testing Recommendations The diagnosis of latex allergy includes many factors. The presence of latex-specific IgE is an important confirmatory test when latex allergy is suspected. A task force on allergic reactions to latex formed by the American Academy of Allergy and Immunology issued a report with a recommended protocol for all patients who would be exposed to latex during medical procedures. The protocol states that all patients who have risk factors for latex allergy should be tested. Risk factors include:
A recent publication presents an algorithm for latex allergy diagnosis.26 Identification of at-risk patients must include questions about latex exposure and reactions as part of the history. For any patient with immediate allergic symptoms such as contact urticaria pruritis, dermatitis, rhinoconjunctivitis or asthma, additional confirmatory testing is required. The recommended first test is a blood test for specific IgE for latex.26 Testing is safe, and a positive result confirms the presence of latex-specific IgE Summary Studies indicating rising incidence of latex allergy in health care workers mean that more people are becoming sensitized to latex and potentially allergic. Latex found in many medical products, but is also found extensively in consumer products. Although latex products have been used for many years, the relatively recent appearance of latex IgE-mediated allergy is not well understood. Latex allergy is now recognized as a potentially fatal condition for some patients who undergo procedures that expose them to latex. The diagnosis and prevention of exposure is the most effective method of preventing life-threatening reactions. Careful clinical histories with confirmatory testing are important for identifying individuals at risk. In vitro testing has been recommended as the first confirmatory test for the diagnosis of latex allergy. References
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