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Contents A. Case study B. More information C. Editors' comments D. References E. CEU questions

Index

A. Case study
An 18-year-old female physiotherapy student was admitted to the emergency unit of the campus hospital with marked oral and facial swelling, urticaria and pruritis to her hands, light-headedness, low blood pressure and difficulty breathing.

She was treated with epinephrine for anaphylaxis, given antihistamine and monitored before an allergist evaluated the possible cause of her allergic reaction. The symptoms started subsiding within 2 hours of treatment.

QUESTIONS AT THIS POINT:
a. Does she have a history of allergic disease, e.g. asthma, hayfever, eczema, food allergy?
b. Has she ever experienced similar reactions before?
c. What food and drink were ingested before the reaction?
d. Was there any associated physical exertion?
e. Was she on any medication which may have induced the reaction?
f. Had she been in contact with a potential irritant, any environmental or other chemical allergen that could have caused the reaction?
g. Could this be a latex-induced allergy?

A thorough patient history provided the following answers:
a. She did have a personal history of asthma and hay fever, and had had a milk allergy with mild eczema as a child. As a child, skin prick tests had shown her to be allergic to house dust mites, moulds and cats. Her mother and her grandmother on her mother’s side suffered from sinusitis and asthma.
b. She could vaguely remember her mother mentioning that as an infant, she had developed a rash around her mouth when drinking from a baby’s bottle or sucking a pacifier; but she had sucked her thumb as a toddler and so couldn’t remember the symptoms and wasn’t sure of the details. She recalled experiencing an itchy sensation in her mouth when eating kiwi fruit, avocado and banana and so tended to avoid these fruits if possible. As she had become older, she had noticed that she could eat kiwi jam, fried banana, pizza with cooked banana, and avocado without a problem.
c. She had eaten a muffin and drunk a cup of coffee with sugar and milk for breakfast; had had a Coke and Mars Bar mid-morning; and had eaten a tuna bake with fresh salad and fruit salad from the cafeteria for lunch. The salad had fresh avocado, in it and the fruit salad contained banana and kiwi fruit. Although she didn’t usually eat raw avocado, banana and kiwi fruit, she ate them this time, as she hadn’t experienced the oral symptoms for a long time and had been eating the “cooked” versions without a problem (see point b. above).
d. Apart from walking in the hospital, she had been doing rehab with a stroke patient after lunch just before the reaction had started. Although she had been helping him to walk and guiding him with the help of a nurse, she had had no physical exertion that day.
e. She was on no medication at the time.
f. As a physiotherapy student, she always had to sterilize her hands with alcohol and wear sterile rubber gloves when treating patients. She found her hands became very dry, and she developed an itchy eczema-like reaction on both her hands. She put it down to the constant washing and sterilising and decided to apply hand cream before wearing the gloves in an attempt to minimize the dermatitis. She did not have any pets and lived in the university residence, which had tile floors and no carpets.
g. She was unsure about any exposure to latex but was sure the hospital used latex-free gloves. As an infant, the pacifier or bottle teat may well have contained latex.

DISCUSSION:
Based on this history, the only part of her day preceding the reaction that was different than usual was the “new” foods she had at lunch: avocado, kiwi and banana. These all contain the panallergen chitinase. If this was the cause of her reaction, then it also correlates with her reactions to her bottle and pacifier as a baby, as well as to the rubber gloves; that is, if they were made from latex (as latex also contains chitinase and is cross-reactive to these foods). However, when asked, the student said that the gloves she used were latex-free, as the academic hospital had a latex free policy.

Latex allergy can cause 3 types of reactions, namely type 1 hypersensitivity, irritant contact dermatitis and allergic contact dermatitis. The speed of her symptoms as well as the combination of symptoms (contact urticaria, pruritis, oral itching, facial oedema, allergic rhinitis and asthma and anaphylaxis) resembled a type 1 immediate latex reaction.

From the history, a number of risk factors were also identified: she was female and a health professional and had a history of atopy and hand eczema of unknown cause, all of which could mean an increased predisposition to natural rubber latex hypersensitivity.

QUESTIONS AT THIS POINT:
a. What tests should be done to confirm a suspected latex/chitinase allergy?
b. Could she be reacting to latex-free gloves and if so, why?
c. If she was allergic to the fruits, then why did she seem to react to the raw and not the cooked forms?

DISCUSSION:
a. Skin prick tests and serum-specific IgE tests for latex can be performed in conjunction with a detailed clinical history. Due to her severe reaction, a blood test was done, as it would not pose a risk for an anaphylactic reaction. Blood tests were positive for latex but negative for avocado and kiwi fruit.
b. Closer inspection of the gloves revealed that they were low-protein but not latex-free. They were also powdered, and powdered gloves tend to have higher levels of latex allergens because of leaching of the allergen into the powder. Her practice of applying hand cream before putting on the gloves could also increase the risk of natural rubber latex protein transfer to the skin.
c. A latex allergy can result in latex fruit syndrome due to cross-reacting allergens in a variety of plant sources. Fruits and vegetables which contain the cross-reacting allergen chitinase include kiwi, papaya, mango, tomato, banana, chestnuts, passion fruit, beans and legumes. The allergenicity of class 1 chitinase can be altered by means of cooking or ripening or plant stress. Heating deactivates the allergenicity, while ripening may enhance it. Blood tests may be negative if the extract used does not contain the responsible allergens or has denatured over time. Skin prick tests using fresh extracts or the prick-prick method are preferable and may be more accurate, as proteins in commercial fruit allergen extracts usually denature quickly.

When prick-by-prick testing with the fresh products was done, it was positive. She was diagnosed with type 1 hypersensitivity to latex with cross-reactions to the class 1 chitinase-containing plants. The hospital was informed of the dangers of latex exposure in the work environment and the need to re-evaluate its prevention programme.

TIP for Allergy Advisor users: Information from Allergy Advisor that can assist in the treatment of a latex allergy is a list of latex-containing foods under “Management” / ”Patient Information Sheets”. And if it is the chitinase in the latex that the person is allergic to, a diet sheet of foods to avoid and that are allowed can be found under “Management” / ”Diet sheets”.

B. More information:
During the last 100 years, latex products have become ubiquitous. Latex forms the main constituent of over 40 000 medical and consumer products. Its popularity is attributed to its unique biomechanical performance characteristics, which include strength, elasticity, flexibility, durability, tear resistance, and superior barrier qualities.^1,2

In the past, complications stemming from the use of latex products were thought to be limited to contact dermatitis, but during the last 2 decades, the prevalence of latex allergy has reached epidemic levels. Latex allergy is known to be an immune-mediated hypersensitivity response (immediate or delayed) to natural rubber latex (NRL) protein.^1,2

In developed nations such as the USA and Europe, specific primary and secondary preventative guidelines have been successful in reducing the incidence in high-risk populations, specifically within the medical field. In developing, population-dense nations striving to attain higher economic and technological standards, such as China, India and Mexico, an increased incidence of latex allergy is expected in various industries in the future.³

1. What is latex, and where is it found?

Natural rubber latex (NRL) is derived from the milky sap, or latex, of the commercial rubber tree, Hevea brasiliensis, which grows in Africa and peninsular Malaysia. NRL is composed of spherical polyisoprene droplets coated with a layer of water-soluble proteins. It is filtered and preserved with either sodium sulfite, formaldehyde, ammonia, or a mixture of ammonia zinc oxide or tetramethylthiuram disulfide, to form field latex, which is then processed into dipped or dry rubber products.2,4,5,6,7,8 Dipped latex products include surgical, dental and household rubber gloves, balloons, tourniquets, catheters, condoms and diaphragms; these are all produced by dipping porcelain forms into liquid latex. NRL concentrate contains about 1% total protein, a small fraction of which remains in the product as residual extractable proteins. These extractable proteins are responsible for the immediate-type reactions to NRL.2,5,9,10,11,12,13

Dry rubber latex comprises products made from processed, dried, or milled sheets of latex rubber. Car and bike tyres, syringe plungers, vial stoppers, and shoe soles are examples of extruded or compression-moulded dry products. Dry rubber latex products contain lower residual protein levels or less easily extracted proteins than do NRL products and are less immunogenic.^{2,5,9,10,11,12,14,15}

Latex can be also be found in rubber bands, bandages, balls, erasers, paints, hot water bottles, clothing with elastic and other rubberized material (underwear and raincoats), children’s toys, bottle teats, pacifiers, nose cleaners, teethers, sports equipment (squash balls), swimming caps, carpet backings and enema tubes. The wrappers and packaging used for a wide variety of foods, as well as food handled with latex, may contain hidden quantities of latex rubber, enough to trigger fatal allergic reactions in some people.^{2,8,16,17,18,19,20}

Although there are more than 250 separate proteins in natural rubber latex, less than one fourth may show reactivity with IgE antibodies.^2,5,6Latex allergy seems to be more complex than other allergies, as it stems from no fewer than 13 known latex allergens (Hev b 1 to Hev b 13), which have been recognised by the International Union of Immunological Societies as being responsible for triggering an allergic response to latex.^3,9,21

Latex allergic patients are each sensitised to at least one latex protein among Hev b 1 through Hev b 13. Most of these proteins are water-soluble, with allergenic fractions having molecular weights ranging from 5 to 115 kDa. Certain of the allergens are considered major while others are minor, with different allergens playing more prominent roles in certain latex-allergic groups. ^2,8,21,22,23

Based on the results of published studies, the following major allergens appear to be relevant in different population groups:

• Latex-sensitised adults - Hev b 2, Hev b 5, Hev b 6, Hev b 13 and possibly Hev b 4 ²¹
• Healthcare workers - Hev b 2, Hev b 5, Hev b 6, Hev b 7 and Hev b 13 ^{7,21,23,24,25}
• Children with spina bifida and meningomyelocoele - Hev b 1 and Hev b 3 ^2,23

Apart from the major NRL allergens, another components in NRL, lysozyme, shows binding to IgE from patients with latex allergy.²

Recombinant latex allergens are usually synthesised from E. coli; they are clinically reactive and can be produced in a standardised manner to potentially provide safe and sensitive reagents for the diagnosis and desensitisation of type I latex allergy. Although there is an increasing tendency to identify and characterise latex allergens largely on the basis of their recombinant forms, not all such recombinant proteins have been fully validated against their native counterparts with respect to clinical significance.^21,22

2. Incidence, high risk groups and risk factors for sensitization and hypersensitivity
There is little exact epidemiological data on the prevalence and incidence of latex allergy.
In the general population, latex allergy appears to be low, affecting approximately 1%, while latex sensitisation is estimated to be around 2%. Known risk groups, however, show a higher prevalence of latex allergy, ranging from 10-65%, depending on the group and the study.^{2,4,5,7,8,13,26}

Latex sensitisation implies a positive in vivo or in vitro test to latex, whereas allergy is diagnosed from a combination of a positive test and compatible clinical symptoms. In the USA and Europe there appears to be a gradual rise in the rate of latex sensitisation, while the rate of clinically symptomatic latex allergy seems to be on the decline. At least 40% of patients diagnosed through either in vivo or in vitro tests as being sensitised to NRL will be asymptomatic. This has been attributed to the fact that either they are not sufficiently sensitised or they are not exposed to sufficient levels of allergen. This clinical “hiding” of latex sensitisation may also be related to heightened awareness of NRL allergy in conjunction with improved diagnostic testing, improved glove manufacturing, and the efficacy of other preventive measures.²

Anyone who routinely wears NRL or powdered latex gloves is exposed to latex medical products or is regularly exposed to NRL in an occupational setting may be at risk of developing latex allergy. Healthcare workers and emergency medical workers form the largest groups at risk. (Clinically symptomatic latex allergy is estimated to affect up to 20% of health care providers.) Those who may specifically be affected in the medical profession include physicians, dentists, surgeons, operating room personnel, dental assistants, laboratory personnel, hospital housekeeping personnel, and ambulance attendants.² Food industry workers also form a significant group affected by latex hypersensitivity.

A recent Spanish study found sensitisation to NRL much more common in healthcare workers than in non-healthcare workers, affecting 16.7 versus 2.3%. Those non-healthcare workers most affected included food handlers (17.1%), construction workers (6.6%), painters (6.2%), hairdressers (5.1%) and cleaners (3.8%).²⁷

Other groups at high risk include children with spina bifida or meningomyelocoele (due to the tendency to develop bladder infections that require catherterisation or constant indwelling catherters), latex industry workers, housekeepers, cleaners, rubber band, surgical glove and latex doll manufacturing workers, specific food-allergy patients, and patients with a history of atopy or multiple surgical procedures.^1,2,4,5,28.

The number of reports of non-occupational cases of latex allergy in which the reactions have occurred at home, in individuals who have no occupational exposure to NRL or history of frequent surgical procedures, is increasing, probably reflecting significant exposure of the general population to a variety of latex devices, cross-reacting fruits or pollens. Restaurant and postal workers, security personnel at airports, police, and consumers may be affected.^2,18 Due to the possible severity of clinical reactions and the large spectrum of the population that may be affected, latex should be considered a significant potential allergen.

Apart from profession, other risk factors for latex sensitivity and allergy include:
• Age - the risk of sensitisation tends to decrease with age.²
• Female gender - there appears to be a female predominance in most reports of NRL glove allergy.^2,4,5
• Atopy - Latex allergy has been four times more common in atopic individuals than in non-atopic controls.^2,29
• Pre-existing hand eczema – This is present in more than half of patients with NRL allergy. Chronic hand eczema and atopy often coexist, and such patients often wear NRL gloves that increase their exposure to NRL protein allergens.^2,5
• Patients with histories of multiple surgical interventions or multiple congenital anomalies necessitating serial diagnostic procedures ^2,5,6,10

3. Adverse reactions to latex
Latex allergy refers to IgE-mediated, type I (immediate) and cell-mediated type IV (delayed) hypersensitivity reactions. A third possible type of reaction is the so-called irritant contact dermatitis which is often associated with but not caused by latex itself but rather the alkaline pH found in powdered gloves or other compounds used in the manufacture of latex.^1,2,30

Type IV delayed-type hypersensitivity is also known as allergic contact dermatitis and is usually caused by chemical accelerators (such as thiurams, carbamates, and benzothiazoles) or antioxidants added to cure natural or synthetic rubber. This cell-mediated reaction develops 24 to 48 hours after exposure and is diagnosed with patch testing. Aside from NRL gloves, other currently available synthetic alternatives may also pose a risk for allergic contact dermatitis, depending on the chemicals used for their production.2,5,6,7,20,31 Type I immediate hypersensitivity (IgE-mediated) to latex is caused by NRL proteins present in natural or cured rubber latex. Clinical symptoms of NRL allergy are dependent on individual susceptibility to the allergen, the mode and route of exposure, and the type and amount of bioavailable protein allergen. Exposure to latex antigens can occur by cutaneous, respiratory, mucosal and parenteral routes, with the latter two routes producing the greatest risk for anaphylaxis. Symptoms usually result from direct contact with an NRL product but may also result from inhalation of aerosolised powder containing NRL proteins. Clinical manifestations may include localised pruritus, burning or stinging, contact urticaria, generalised urticaria, allergic rhinitis, allergic conjunctivitis, angioedema, bronchial asthma and even fatal anaphylaxis.2,5,8,11,29 Both type IV and type I allergy to latex represent serious problems, as the exposure may cause life-threatening (type I) or career-threatening (type IV) reactions.2,32 Concomitant hand eczema may be another manifestation of latex allergy. It is important to emphasise that concomitant type IV and type I allergies to rubber products may occur in the same patient. Chronic hand eczema may also occur without type IV allergy to rubber chemicals and may resolve upon withdrawal of latex gloves. Irritant or allergic contact dermatitis may further facilitate type I sensitisation to latex by disrupting the epidermal barrier and allowing latex proteins to penetrate the skin.2,5,6,8

Although cutaneous exposure to NRL most likely results in contact urticaria, and extracutaneous symptoms including allergic rhinitis, allergic conjunctivitis, facial edema, and bronchial asthma; even some cases of anaphylaxis have been reported.^2,5

4. Cross-reactivity
Allergic reactions to multiple fruits and other foods appear to occur with unusual frequency and severity in individuals with latex allergy. At least half of latex-allergic patients have fruit/ food sensitivity, and up to half of these patients experience serious reactions from foods. Some of the latex allergens are structurally similar to antigens in some fruits, vegetables and nuts, which may explain this reactivity (e.g., Hev b 6.02 is an amino acid fragment of prohevein; Hev b 2, a ß-gluconase; Hev b 11, a class 1 chitinase; Hev b 7, patatin-like molecule; Hev b12, a lipid transfer protein; and Hev b 13, a lipolytic esterase). The latex allergen hevein (Hev b 6.02) and the plant panallergens class 1 chitinases seem to be responsible for most cases of latex-fruit syndrome.^{9,21,26,33,34,35,36}

These immunologic cross-reactivities among NRL proteins and fruits and vegetables of phylogenetically different sources result from homologous proteins belonging to particular protein families: patatin, profilin, papain, bromelain, chitinase, glucanase, and hevein. Variable degrees of cross-reactivity can be expected among foods and plants containing a particular panallergen. ^{2,5,11,26,33,34,35,36,37,38,39,40,41,42,43}

Therefore, cross-reactions have been reported among latex and avocado, chestnut, banana, and kiwi (the four most frequently implicated foods in this syndrome), papaya, walnut, melon, peach, plum, celery, carrot, apple, pear, mango, apricots, grapes, passion fruit, pineapples, citrus fruits, fig, wheat, barley, hazelnut, potato, tomato, lettuce, bell peppers, spinach, dill, sage and oregano; each latex-associated food is implicated by the panallergen present in that food.^{2,5,11,26,33,34,35,36,37,38,39,40,41,42,43}

Not everyone with latex allergy will develop symptoms when exposed to potentially cross-reacting foods. Some individuals with latex-food allergy may be uniquely sensitised to the antigens that are present in a particular food, simultaneously demonstrating clinical reactions to both the food and to the NRL products. Therefore, a pre-existing fruit allergy may represent an additional risk factor for a clinically relevant latex allergy. Alternatively, some patients with latex allergy may have IgE-antibodies to fruits or plants without ever having eaten them. Thus, it is not always clear whether latex sensitisation precedes or follows the onset of food allergy.^{2,5,9,11,21,36,37,38,39,40,41,42,43}

More recently, foods from the botanical family prunoideae, such as peach, apricot and almond, may partially be responsible for the unexpectedly high prevalence of food allergy in latex-allergic patients.^{2,5,11,26,33,34,35,36,37,38,39,40,41,42,43}

Allergic reactions to milk may also be associated with the manufacture of latex and have been attributed to the addition of casein powder, sometimes used to coat latex gloves.^2,5 Latex-allergic patients may also have allergy to pollens (such as ragweed and grass), because of profilin, which cross-reacts with latex.^2,26 Recently, homology between latex allergens and mould allergens has been termed the “latex–mould syndrome”.²⁶ Even tobacco has been reported to contain prohevein-like defense-related protein, which may cross-react with latex.⁴⁴

Patients with food allergy may present with a variety of manifestations, including oral itching, generalised pruritus, hives, angioedema, laryngospasm, nausea, vomiting, pyrosis and dyspnoea after eating foods that cross-react with latex. The initial manifestation may even be as severe as anaphylaxis.^{2,5,11,26,33,34,35}

5. Diagnosis The accurate diagnosis of a latex-allergic individual begins with a comprehensive clinical history. If symptoms are temporally delayed (by hours or days) and confined to skin-latex product contact areas, Type IV hypersensitivity should be suspected and patch testing may be performed to identify activated T-cells that are specific for selected rubber chemical additives. If ocular, upper and lower airway, and/or systemic allergic symptoms are observed with rapid onset (minutes) following a definable latex exposure, Type I hypersensitivity should be suspected. One or several confirmatory tests for latex-specific IgE antibody in the skin or blood may next be performed to verify a sensitised (IgE antibody-positive) state. If the clinical history remains discordant with a skin test or blood test result, in vivo provocation tests may be cautiously considered for evaluation.45,46,47 Hevea brasiliensis latex serum is commonly used as the in vivo and in vitro reference antigen for latex allergy diagnosis, as it contains the full complement of latex allergens. However, latex allergy diagnostis and immunotherapy that use whole latex serum as the antigen source may not be optimal because of the marked imbalance of its constituent allergens.48 Non-purified latex has variations in allergen content, making it unsuitable for use as a reference material. The need for well-defined and standardised NRL extracts and/or purified proteins is important, as a test reagent formulated from purified allergens (native or evaluated recombinant latex allergens) has the advantages of better test sensitivity, specificity and reproducibility. Ideally, the design of diagnostic latex reagents for both in vivo and in vitro tests should be based on the representation of all allergenic proteins of NRL.2,30,45 Identification of the major latex allergens and their recombinant production and the determination of the specific sensitisation profiles for different groups have been useful steps towards understanding latex allergy and its diagnosis. However, not all latex allergens have been cloned, and therefore a mixture of recombinant allergens may not have the full repertoire of the allergens present in natural rubber latex; so testing with individual allergens may miss individuals not allergic to that allergen but to other latex allergens.

In vitro tests
Latex-specific IgE antibodies in serum can be demonstrated in vitro and quantified with RAST (ImmunoCAP®) or enzyme-linked immunosorbent assay (ELISA). The results of these tests are categorised in 7 classes, where an IgE level of < 0.35 ku/l (Class 0) indicates absence, and levels between 0.35 – 49.9 ku/l (Class I–VI) indicate the presence of latex-specific IgE. A positive in vitro test result may be diagnostic of latex allergy, although RAST results of a level of 0.70 – 3.49 ku/l (Class 2) or greater tend to be interpreted as positive. The disadvantages of serological testing include the cost, delayed results, lower sensitivity in testing for latex allergy, and accessibility as compared with in vivo testing; however, it should be the initial diagnostic step in suspected latex allergy, because it is safer than in vivo tests.^{2,5,6,7,8,45,46,47}

In vivo tests
Skin prick testing (SPT) is the gold standard in the diagnosis of latex allergy, and when interpreted with clinical history, it provides the most reliable method of diagnosis.²¹Compared to in vitro serological assays, SPT offers the advantages of being substantially more sensitive, cheaper, easier to perform, and immediate in its results. However, the sensitivity of SPT is profoundly influenced by the quality of the latex extract used.⁴⁹ Because the sensitivity of a single latex allergen extract is below 100%, it is important to use a panel of latex extracts to increase sensitivity.⁵⁰ SPT should be performed by experienced staff and with oxygen, epinephrine and latex-free resuscitation equipment on hand.^{2,5,7,21,45,46,47} It is, however, contra-indicated if life-threatening anaphylaxis has been experienced.

Challenge tests (nasal, conjunctival, bronchial, intravaginal, sublingual, oral, and cutaneous) are important for confirming the diagnosis, for evaluating a patient's response to the different kinds of latex exposure, and for verifying the effects of desensitising treatments on the various organs involved in latex allergy.^2,45,46,47

The wear test (or use test) is a validated glove provocation procedure and may be employed when there is a discrepancy between SPT or specific IgE results and clinical history.^2,45

In patients with hand eczema, patch testing may reveal allergens relevant to delayed type hypersensitivity to rubber accelerators and antioxidants (mercaptobenzothiazole, black rubber mix and carbamates), glutaraldehyde, latex gloves, vinyl gloves, preservatives and NRL.^2,5,8

Differentiation should be made between latex sensitisation, which implies a positive in vivo or in vitro test to latex, and latex allergy, which is a combination of a positive test and compatible clinical symptoms. At least 40% of patients diagnosed as being sensitised to NRL with either in vivo or in vitro tests will be asymptomatic. This is either because they are not sufficiently sensitised or because they are not exposed to sufficient levels of allergen. This clinical “hiding” of latex sensitisation may also be related to heightened awareness of NRL allergy in conjunction with improved glove manufacturing, improved diagnostic testing, and the efficacy of preventive measures.^2,5,29,31,39

6. What responsibility does the medical and food industry have?
Both the medical and food industries need to become aware of the increasing risk that employees may be exposed to latex in the workplace and sensitised. The vastly widespread use of rubber gloves in these industries for hygienic purposes has meant that latex allergy may have a profound impact on employee health, attendance and ultimately productivity. A latex allergy can be regarded as a major occupational disease.

Furthermore, latex may contaminate foodstuffs and become a risk to all latex-allergic individuals.
In the UK, contamination of food wrappers and packaging with latex was shown to lead to latex transfer over to food. Contamination by rubber proteins was also discovered in ice lollies and pastry, in stickers used on fresh produce such as avocados and apples, on rubber bands used to tie spring onions and asparagus, and in the netting that keeps joints of meat intact. Use of latex gloves by workers in the food industry is also a potential source of food contamination.¹⁶

At present, manufacturers are not required to include latex warnings on packaging labels. The consumer is therefore increasingly vulnerable to exposure. This has prompted calls for new labelling rules to ensure that consumers are aware of the use of latex in packaging, since as little as a billionth of a gram (1 ng/ml) has been known to trigger an allergic response.¹⁶

Some points to be aware of regarding glove usage are that powdered latex gloves generally contain larger amounts of NRL allergens than non-powdered gloves, and non-sterile examination gloves contain higher levels of allergen than sterile surgical gloves. Hand creams applied before donning gloves may actually increase NRL protein transfer to the skin instead of protecting the skin and may play a role in sensitisation to latex gloves.^{1,2,4,5,11,51,52,53}

The risk of latex sensitisation or latex allergy can be minimised by decreasing the amount of extractable proteins in latex products. The amount of leachable allergens in latex products is a more relevant determinant of safety.^2,4,31,51

In both industries, simple measures such as avoidance of unnecessary glove use, the use of non-powdered latex gloves by all health workers, and the use of latex-free gloves by sensitised subjects can stop the progression of latex symptoms and prevent new cases of sensitisation. The routine use of NRL gloves by food handlers, housekeepers, and gardeners should also be discouraged. All food in cafeterias and restaurants should be prepared by workers wearing non-latex gloves. Food service workers need to be educated on the potential hazards of latex gloves and on the types of alternative gloves.^{2,4,5,11,16,51}

Although a variety of synthetic gloves is now available as substitutes for NRL gloves, their higher cost and the advantages of latex have meant that the use of these synthetic gloves has been met with resistance. Their availability is increasing, however, and will probably continue to increase as the demand does. The use of latex-free gloves not only benefits the health of workers in settings where latex gloves are commonly used, such as the hospital sector and the food service industry, but also promises cost and human resource savings to these industries.^{1,2,4,5,11,51,52,53}

Labelling regulations should be enforced to warn about the use of latex in the medical or food industries.^{1,2,4,5,15,24,51,52}

Healthcare facilities should institute a complete intervention policy and adopt the exclusive use of non-latex synthetic or non-powdered, low-protein latex gloves as well as latex-free equipment. Air conditioner flow should also be evaluated, to prevent dust from powdered gloves being re-circulated in a room. Apart from endangering the workers, NRL gloves in a healthcare facility carry the risk of sensitising patients. A multidisciplinary team should be set up to deal with latex-allergic employees and patients and to develop prevention programs.^{1,2,4,5,24,51,52}

Primary prevention programmes should be considered in both industries, with a transition to a latex-safe environment; in case latex gloves are necessary, the use of non-latex gloves or powder-free, reduced-protein, low-allergen gloves has been shown to decrease the rate of sensitisation in high-risk groups, and the occurrence of allergic reactions among already sensitised workers. Such a policy would be cost-effective as compared to worker’s compensation claims, replacement costs for highly skilled workers, and the costs associated with the absence and treatment of workers.^{1,2,4,5,10,11,13,14,24,29,50,51,52}

Secondary prevention programmes can also be implemented, wherein sensitised workers are encouraged to report and document their reactions; diagnostic testing can be followed by re-accommodation in NRL-safe environments. Employers should periodically screen high-risk workers and provide workers with education programs and training materials about latex allergy. Every attempt should be made to accommodate workers and to preserve their current occupation. Education should form an important part of the secondary prevention programmes.^2,4,5,11

7. Management of latex allergy
At present, there is no cure for latex allergy, and personal or environmental latex avoidance and substitution is the only available treatment. It is the key to preventing allergic reactions in latex-sensitised individuals.^1,7

Latex-allergic individuals should be made aware of potentially cross-reacting foods, due to the risk of anaphylaxis; the longer the allergic person is exposed to the antigens, the greater the risk. Continued exposure to NRL allergens may result in increasing sensitivity over time, so pre-medication with antihistamines and systemic corticosteroids should not be an alternative to careful allergen avoidance. Their use may also mask early expression of allergic reactions.^1,2,5,8,9,13

Complete avoidance, particularly in medical settings, is practically impossible because of the abundance of NRL containing products, so the realistic aim should be to minimise latex exposure. As mentioned previously, primary as well as secondary latex avoidance programmes have been shown to be effective in reducing the risk of latex sensitisation in high-risk individuals and may even lead to a decrease in latex-specific IgE levels or a complete resolution of allergy symptoms.^2,4,28,32

Latex-allergic patients should obtain Medic-Alert bracelets and inform healthcare providers and their employers of their diagnoses. Patients with systemic symptoms should carry auto-injectable epinephrine syringes. The use of beta-blockers should be avoided in NRL-allergic patients, as it may block therapeutic response to anaphylaxis treatment drugs.^2,5,6,8,13

C. Comments by our editors

Prof Janice M. Joneja Ph. D., RDN On several occasions I have been asked the question, “If a hospital in-patient has a latex allergy, should his or her meals be free from all of the foods that are known to contain structurally similar antigens?” The question is prompted by the fact that if the patient does have an allergic reaction, and in extreme cases, an anaphylactic reaction, to foods that are known to cross-react with latex, will the hospital be legally liable for negligence? My usual answer is that a hospital dietitian should interview the patient on admission and determine whether he or she has ever reacted to any of the foods known to cross-react with latex. Those to which no reaction has been exhibited, and which the patient has eaten regularly, are probably safe and can be included in the hospital diet. Those which should be avoided are those to which the patient has reacted, even mildly, and those which are not eaten regularly, or not at all. However, I am never sure that that is the correct answer, since evidence has been presented to suggest that even the initial reaction to a latex-associated food can be as severe as anaphylaxis. I would like to hear from interested stake-holders, what policies are in place in other hospitals to deal with this problem. I would also like to share an interesting situation to do with the subject of latex allergy that I recently encountered. It serves as food for thought: In my local supermarket I went to a check-out where there was a large notice telling customers that if they had any of the following foods in their baskets, they should go to another cashier. The foods listed included bananas, kiwi fruit, avocado, chestnut, papaya, tomato, and a number of others. I asked the cashier whether she had latex allergy, to which she replied, quite belligerently, that she did, and that her allergist had told her to avoid all of the foods on the list because she was at risk of having a “life-threatening allergic reaction”! It was clear that under the human rights legislation in Canada, her employer could not remove her from her position on the basis of a “medical disability” – so there she stayed - her employer and customers would just have to cope with the situation. This went on for several months. In light of her attitude, I was reluctant to point out to the cashier that when her allergist told her to avoid the foods on her list, he had meant her to avoid eating them, not that she needed to avoid merely touching them! I meekly went to another check-out.

Dr. Harris Steinman M.B.Ch.B. This review highlights an allergy that is still evolving: the prevalence of latex allergy is increasing and our understanding of its clinical and molecular aspects has not been fully elucidated. Once rare, some opinion leaders suggest that it be added to the list of allergens that legislation requires specific labelling for, e.g., egg, wheat, milk, peanut, etc. It is therefore very important for all health workers to have knowledge regarding this potent allergen. Prof. Janice Joneja also raises an interesting point of cross-reactivity - the implications of cross-reactivity. May a student with kiwi and mango allergy enroll to study dentistry or should he/she find another occupation with less risk of exposure to latex?

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D. References
1. Woods JA, Lambert S, Platts-Mills TAE et al. Natural rubber latex allergy: spectrum, diagnostic approach, and therapy. The Journal of Emergency Medicine 1997. Vol 15; 1: 71-85
2. Taylor JS, Erkek E. Latex allergy: diagnosis and management. Dermatologic Therapy 2004; 17: 289–301
3. Wagner S, Breiteneder H. Hevea brasiliensis Latex Allergens: Current Panel and Clinical Relevance. Int Arch Allergy Immunol 2005; 136: 90-97
4. Toraason M, Sussman G, Biagini R et al. Latex allergy in the Workplace. Toxicology Sciences 2000: 58; 5-14
5. Taylor JS, Wattanakrai P, Charous BL, Ownby DR. Year book focus: latex allergy. In: Thiers BH, Lang PG, eds. 2000 year book of dermatology and dermatologic surgery. St. Louis: Mosby Inc., 1999: 325–368.
6. Kashima ML, Tunkel DE, Cummings CW. Latex allergy: an update for the otolaryngologist. Arch Otolaryngol Head Neck Surg 2001: 127: 442–446.
7. Hepner DL, Castells MC. Latex allergy: an update. Anesth Analg 2003; 96: 1219–1229.
8. Marks JG, Elsner P, Deleo VA. Contact urticaria. In Contact and occupational dermatology, 3rd ed. St. Louis: Mosby Inc., 2002: 395–399.
9. Joneja JV. Dietary management of food allergies and intolerances – a comprehensive guide 2nd edition. Chapter 7 p116-118. Bull Publishing Company 2003, Boulder, Colorado USA.
10. Elliott BA. Latex allergy: the perspective from the surgical suite. J Allergy Clin Immunol 2002: 110 (2 Suppl.): S117–S120.
11. Zucker-Pinchoff B, Stadtmauer GJ. Latex allergy. Mt Sinai J Med 2002; 69: 88–95.
12. McFadden ER Jr. Natural rubber latex sensitivity seminar: conference summary. J Allergy Clin Immunol 2002; 110 (2 Suppl.): S137–S140.
13. Charous BL, Tarlo SM, Charous MA, Kelly K. Natural rubber latex allergy in the occupational setting. Methods 2002; 27: 15–21.
14. Hunt LW, Kelkar P, Reed CE, Yunginger JW. Management of occupational allergy to natural rubber latex in a medical center: the importance of quantitative latex allergen measurement and objective follow-up. J Allergy Clin Immunol 2002; 110 (2 Suppl.): S96–S106.
15. Farnham JJ, Tomazic-Jezic VJ, Stratmeyer ME. Regulatory initiatives for natural latex allergy. US Perspectives Meth 2002; 27: 87–92.
16. Published in Chemistry and Industry. Latex in food wrappers, packaging and rubber gloves must be declared. News-Medical.Net, Medical Studies/Trials, Published: Monday, 7-Aug-2006
17. Kimata H. Latex allergy in infants younger than 1 year. Clin Exp Allergy. 2004 Dec; 34 (12): 1910-5
18. Condemi JJ. Allergic reactions to natural rubber latex at home, to rubber products, and to cross-reacting foods. J Allergy Clin Immunol 2002; 110 (2 Suppl.): S107–S110.
19. Patriarca G, Nucera E, Buonomo A, et al. Latex allergy desensitization by exposure protocol: five case reports. Anesth Analg 2002; 94: 754–758.
20. Ventura MT, Dagnello M, Matino MG et al. Contact dermatitis in students practicing sports: incidence of rubber sensitisation. Br J Sports Med 2001; 35: 100–102.
21. Yeang HY. Natural Rubber latex allergens: new developments. Curr Opin Allergy Clin Immunol 2004; 4: 99-104
22. Sussman GL, Beezhold DH, Kurup VP. Allergens and natural rubber proteins. J Allergy Clin Immunol 2002; 110: S33-9
23. Yeang HY, Arif SA, Yusof F, Sunderasan E. Allergenic proteins of natural rubber latex. Methods 2002: 27: 32–45.
24. Sastre J, Raulf-Heimsoth M, Rihs HP et al. IgE reactivity to latex allergens among sensitized healthcare workers before and after immunotherapy with latex. Allergy 2006 Feb; 61(2): 206-10
25. Bernstein DI, Biagini RE, Karnani R, et al. In vivo sensitization to purified Hevea brasiliensis proteins in health care workers sensitized to natural rubber latex. J Allergy Clin Immunol 2003; 111 (3): 610–616.
26. Turjanmaa K, Makinen-Kiljunen S. Latex allergy. Prevalence, risk factors, and cross-reactivity. Methods 2002; 27: 10–14.
27. Valks R, Conde-Salazar L, Cuevas M. Allergic contact urticaria from natural rubber latex in healthcare and non-healthcare workers. Contact Dermatitis 2004 Apr;50(4):222-4.
28. Reider N, Kretz B, Menardi G et al. Outcome of a latex avoidance program in a high-risk population for latex allergy – a five-year follow-up study. Clin Exp Allergy 2002; 32: 708–713.
29. Schmid K, Christoph Broding H, Niklas D, Drexler H. Latex sensitization in dental students using powder-free gloves low in latex protein: a cross-sectional study. Contact Dermatitis 2002; 47: 103–108.
30. Rihs HP. Raulf-Heimsoth M. Natural rubber latex allergens: Characterisation and evaluation of their allergenic capacity. New Horizons 2003; 3: 1-10
31. De Jong WH, Geertsma RE, Tinkler JJ. Medical devices manufactured from latex: European regulatory initiatives. Methods 2002; 27: 93–98.
32. Meade BJ, Weissman DN, Beezhold DH. Latex allergy: past and present. Int Immunopharmacol 2002; 2: 225–238.
33. Blanco C. Latex-fruit syndrome. Curr Allergy Asthma Rep. 2003 Jan; 3 (1): 47-53
34. Wagner S, Breiteneder H. The latex-fruit syndrome. Biochem Soc Trans. 2002 Nov; 30 (Pt 6): 935-40
35. Perkin JE. The latex and food allergy connection. J Am Diet Assoc. 2000 Nov; 100 (11): 1381-4
36. Asero R, Mistrello G, Roncarolo D et al. Detection of novel latex allergens associated with clinically relevant allergy to plant-derived foods. J Allergy Clin Immunol 2005 June; 115 (6): 1312-1314
37. Yagami T. Allergies to Cross reactive plant proteins. Int Arch Allergy Immunol. 2002; 128: 271-279
38. Condemi JJ. Allergic reactions to natural rubber latex at home, to rubber products, and to cross-reacting foods. J Allergy Clin Immunol 2002; 110: S107-10
39. Levy DA, Mounedji N, Noirot C, Leynadier F. Allergic sensitization and clinical reactions to latex, food and pollen in adult patients. Clin Exp Allergy 2000; 30: 270-275
40. Sanchez-Monge R, Blanco C, Perales AD et al. Class 1 chitinases, the panallergens responsible for the latex-fruit syndrome, are induced by ethylene treatment and inactivated by heating. J Allergy Clin Immunol 2000 July; 106 (1 Pt 1): 190-195
41. Salcado G, Perales AD, Sanchez-Monge R. The role of plant panallergens in sensitization to natural rubber latex. Curr Opin Allergy Clin Immunol 2001; 1: 177-183
42. Schmidt MH, Raulf-Heimsoth M, Posch A. Evaluation of patatin as a major cross-reactive allergen in latex-induced potato allergy. Ann Allergy Asthma Immunol 2002; 89: 613-618
43. Wagner S, Radauer C, Hafner C et al. Characterisation of cross-reactive bell pepper allergens involved in the latex-fruit syndrome. Clin Exp Allergy 2004; 34: 1739-1746
44. Hanninen AR, Kalkkinen N, Mikkola JH, et al. Prohevein-like defense protein of tobacco is a cross-reactive allergen for latex-allergic patients. J Allergy Clin Immunol 2000; 106: 778–779.
45. Hamilton RG. Diagnosis of natural rubber latex allergy. Methods 2002; 27: 22–31.
46. Patriarca G, Nucera E, Buonomo A et al. New insights on latex allergy diagnosis and treatment. J Investig Allergol Clin Immunol. 2002; 12 (3):169-76.
47. Hamilton RG, Peterson EL, Ownby DR. Clinical and laboratory-based methods in the diagnosis of natural rubber latex allergy. J Allergy Clin Immunol. 2002 Aug; 110 (2 Suppl): S47-56
48. Yeang HY, Hamilton RG, Bernstein DI et al. Allergen concentration in natural rubber latex. Clin Exp Allergy 2006 Aug; 36 (8): 1078-1086
49. La Grutta S, Mistrello G, Varin E et al. Comparison of ammoniated and non-ammoniated extracts in children with latex allergy. Allergy 2003; 58 (8): 814–818.
50. Brehler R, Kutting B. Natural rubber latex allergy: a problem of interdisciplinary concern in medicine. Arch Intern Med 2001; 161: 1057–1064.
51. La Montagne AD, Radi S, Elder DS et al. Primary prevention of latex related sensitisation and occupational asthma: a systematic review. Occup Environ Med. 2006 May; 63(5): 359-64
52. Filon FL, Radman G. Latex allergy: a follow up study of 1040 healthcare workers. Occup Environ Med. 2006 Feb; 63 (2): 121-5
53. Smith Pease CK, White IR, Basketter DA. Skin as a route of exposure to protein allergens. Clin Exp Dermatol 2002; 27: 296–300.


E. CPD Questions (For South African dietitians only. Australian dietitians: where you have relevant learning goals, CEU hours related to this resource can be included in your APD log.)

PLEASE ANSWER ALL THE QUESTIONS
(There is only one correct answer per question.)

1. True or False: Dry rubber latex products contain higher residual protein levels and are more immunogenic than dipped rubber latex products.
a. True
b. False

2. How many latex allergens are recognised by the International Union of Immunological Societies as being responsible for triggering an allergic response to latex?
a. Three
b. Thirteen
c. Ten
d. Twenty
e. Thirty

3. The following major allergens appear to be relevant in healthcare workers:
a. Hev b 2, Hev b 5, Hev b 1 and Hev b 3
b. Hev b 5, Hev b 6, Hev b 13 and Hev b 4
c. Hev b 2, Hev b 4, Hev b 6, Hev b 8 and Hev b 11
d. Hev b 2, Hev b 5, Hev b 6, Hev b 7 and Hev b 13

4. What are some of the risk factors for latex sensitivity and allergy?
a. Age, male gender, asthma, multiple surgeries
b. Female gender, atopy, smoking, pre-existing hand eczema
c. Age, female gender, atopy, pre-existing hand eczema, multiple surgeries, catheterisations and congenital abnormalities (particularly spinal)
d. Female and male gender, atopy, multiple surgeries, catheterisations and congenital abnormalities (particularly spinal)

5. What 3 types of reactions can occur in individuals using natural rubber latex products?
a. Type I hypersensitivity, Type IV allergic contact dermatitis, irritant contact dermatitis
b. Type I, II and III hypersensitivity reactions or allergic contact dermatitis
c. Type I and III hypersensitivity, and irritant contact dermatitis
d. None of the above

6. These are the 4 foods most frequently implicated in fruit-allergy syndrome:
a. Bell pepper, potato, oranges and tomato
b. Tomato, passion fruit, banana and potato
c. Avocado, walnut, pineapple and oregano
d. Avocado, chestnut, apple and kiwi
e. Avocado, chestnut, banana, and kiwi

7. True or False: Skin prick testing (SPT) is the gold standard in the diagnosis of latex allergy and when interpreted with clinical history, provides the most reliable method of diagnosis.
a. True
b. False

8. What factors associated with rubber gloves can increase risk of sensitisation and protein transfer?
a. Non-powdered latex gloves; sterile surgical gloves; no hand cream before wearing gloves
b. Non-powdered latex gloves; non-sterile surgical gloves; no hand cream before wearing gloves
c. Powdered latex gloves; sterile examination gloves
d. Powdered latex gloves; non-sterile examination gloves; hand cream before wearing gloves

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Latex Allergy
CEU Reference number: DTA/06/02/077

HPCSA number: DT
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