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Latex Allergy

Implications for patients and health care workers

The first report of allergic reactions to rubber appeared in 1979. Why have people become sensitive to latex? The use of latex medical products like gloves increased tremendously during the 1980s to reduce possible exposure to infected patients or body fluids. This sudden increase in demand for latex, especially gloves, meant that new manufacturers emerged, that new industrial processes evolved, and that perhaps new or subtly different sources of raw material were used. Products used today may have higher concentrations of allergens as a result of some or all of these changes, or new latex allergens may have been created.

Occupational exposure is widespread. About one million people work in the NHS, and many are exposed to latex. As well as medical and dental personnel, and rubber industry workers, the need to avoid body fluid contact extended exposure to other areas of society. Police officers now routinely use latex gloves when dealing with injured people. Even criminals use latex gloves to avoid leaving fingerprints.

Those receiving health care are also exposed. Patients having operations are obviously exposed to latex. Perhaps less obvious but just as important are dental and anal or vaginal examination.

What is Latex?

Latex describes either the sap of the Brazilian rubber tree ( Hervea brasiliensis) or products made by dipping forms into the sap (gloves, balloons, condoms). Allergic reactions are against proteins naturally present (1%) in liquid latex. Which particular protein is the problem is unclear; one with molecular weight 14,600 is favourite.

The industrial processes of vulcanisation alter proteins. At least one allergen has been found in latex gloves that was not present in rubber sap. The normal source material for medical products is ammoniated latex; the processes include heating to 130 C for 30 minutes in the final phase of glove manufacture. The allergens can be leached from the finished product and are found in the corn starch powder present in medical-use gloves. This powder becomes airborne easily, and inhalation may be one source of contact with latex.

Do many products contain latex?

Yes. Imagine creating an operating room (OR) and an operation without latex products. Some American hospitals now offer latex-free ORs. Some products may be much more of a problem than others. In medicine gloves are the biggest single problem. For some individuals, health care workers or patients, any contact with latex can be life-threatening.

What is latex sensitivity?

There are three different types of reactions to natural rubber latex. They are irritation, delayed hypersensitivity (allergic contact dermatitis) and immediate hypersensitivity (anaphylactic symptoms). Irritation is classed as a non allergic condition. The irritated skin is dry and crusty, and the symptoms resolve when contact with latex ceases.

Delayed hypersensitivity presents as skin becoming dry, crusty and leathery with eruptions appearing as sores and blisters. This response occurs between six and 48 hours after contact. Repeated latex exposure causes the skin condition to expand beyond the area of contact. Many people with delayed hypersensitivity have a history of atopy (allergy, dermatitis, or asthma).

Immediate hypersensitivity is an allergic response mediated by IgE (an antibody found in the circulation). On the skin this can present hives that migrate beyond the point of contact with latex. Systemic allergic symptoms can include itching eyes, swelling of lips or tongue, breathlessness, dizziness, abdominal pain, nausea, hypotension, shock and, potentially, death. These symptoms are likely to result from a massive release of histamine at a local or whole body level. This results from binding of the latex allergen to sensitised receptors on mast cells.

Are there tests for latex allergy?

Yes. There are several available. Skin-prick testing is often thought to be the `gold standard' of sensitivity testing. Latex is introduced into the skin in small quantities at a pinprick site. Positive results are swelling or reddening of the skin, and these can be graded according to size. Skin-prick testing is thought by some to be dangerous, particularly intradermal injection, because of the possibility of life threatening anaphylactoid reactions. Testing has to be performed with the allergen against which the patient is allergic. The different types of available allergen extracts may not contain the particular allergen.

There are also safer in vitro tests. A blood sample is taken and tested for the presence of IgE antibodies specific to latex. There are a number of tests from different manufacturers who may use different latex extracts. Processes which link allergen proteins using amino groups give very good results compared with skin-prick testing. In one study, of 52 skin-prick latex positive patients, 50 were positive by blood tests [1]. The excellent results now possible with blood tests, their relative low cost and freedom from the danger of immediate hypersensitivity associated with skin-prick testing makes them the method of choice, though there may be differences between manufacturers in kit quality for latex.

Studies which have used immunoassays to detect latex-specific IgE have been reviewed critically [1]. Skin and serological testing have been compared directly, and either may be used as a reliable method of diagnosing latex allergy [2].

There is one note of caution. Certain fruits (banana, avocado, chestnut and kiwi fruit) appear to cross-react with latex in allergy testing. These food allergies are extremely rare, and cannot account for the large number of positive reactors in exposed and atopic individuals. The clinical significance of cross-reaction is unknown, but people with cross-reacting IgE antibodies (e.g. food allergy to chestnut) may react when exposed to latex, and vice-versa.

How many health care workers are affected?

As latex allergy has become more widely recognised as an occupational health problem the studies have become bigger and better. Recently 224 hospital employees [3] were interviewed and skin-prick tests performed to six common allergens, one non-latex synthetic glove extract and four different latex glove extracts.

There were 136 nurses, 41 laboratory technicians, 13 dental staff, 11 physicians, 6 respiratory therapists and 17 housekeeping and clerical workers. All tested negative for the non latex glove but 38 (17%) tested positive for latex extracts. The incidence in the different groups was :



Those who were latex positive had significantly higher incidence of bronchial asthma, reported significantly more symptoms when using latex gloves (urticaria, rash, itching, sneezing, nasal congestion, itchy watery eyes and cough), and were significantly more likely to test positive for common allergens (pollen, cat epidermis and dust mites).

The consequences of latex allergy in health workers are not insignificant. Five cases in the USA have been reviewed [4], and give a good picture of the problems at the individual level.

Anecdotal reports in Europe and elsewhere indicate that a number of legal cases involving latex allergy and hospital workers are pending, but the overall clinical relevance to hospital workers needs to be defined.

How many patients are affected?

The only good information is for patients with spina bifida, though there are wide ranges quoted for prevalence. One study of 50 patients aged 2 to 21 years showed that 60% had latex allergy defined by history, serological and/or skin prick tests [5]. This study also showed that allergic patients had undergone significantly more surgical procedures than non-allergic patients (9.5 versus 6.7). In 93 consecutive children with spina bifida [6], 38% were positive for latex antibodies by serological testing and 10% had clinical allergy to latex. The serological test was non-standard, and it may be that this underestimated the prevalence. Using a postal questionnaire of 110 spina bifida children 12% were found to have clinical allergy to latex [7] . Clinical allergy underestimates the presence of IgE antibodies by about four times [6]. It is likely that about 10% of patients with spina bifida will have clinical allergy, and 50-60% will have IgE antibodies specific for latex.

The problem is not confined to spina bifida. Any patient with frequent exposure to latex during surgery is at risk of developing latex sensitivity. The consequences are severe. There is at least one reported case of anaphylactic death after rectal examination with a latex finger stool and FDA reporting has indicated 15 deaths and 400 injuries from latex barium enema tips. There is one documented case of repeated graft rejections caused by latex allergy.

Are there predisposing factors?

569 subjects were examined in a prospective study of risk factors in latex hypersensitivity [8]. There were five groups:-



The results showed that both atopy and exposure to latex increased the likelihood of latex sensitivity, and that the effects were more than additive:-



All the patients in group V had positive skin prick and serological test for latex; eight were atopic and seven had multiple previous surgical procedures (eight or more). Frequency of exposure to latex raised the likelihood of sensitisation 19-fold in nonatopic subjects and 4-fold in atopic subjects. One third of atopic subjects exposed to latex will have latex sensitivity.

What are the implications for health care?

Latex allergy isn't going to go away. Many people have allergies and the number is growing. They are an at-risk group. A large part of the UK workforce suffers occupational exposure to latex - perhaps as many as one million (4%). Patients are increasingly exposed as all healthcare workers now use gloves.

Latex allergy will become important for health authorities and providers, both for their patients and their employees. There are enormous potential employment and public liability issues. Latex reactions are now notifiable to the FDA, and in the US professional groups and hospitals have developed protocols for dealing with latex issues.

A fuller report on latex allergy is available from Bandolier , price £10.

References:

  1. DR Ownby, J McCullough. Testing for latex allergy. Journal of Clinical Immunoassay 1993 16: 109-113.
  2. KJ Kelly, V Kurup, M Zacharisen, A Resnick, JN Fink. Skin and serological testing in the diagnosis of latex allergy. Journal of Allergy and Clinical Immunology 1993 91: 1140-5.
  3. MS Yassin, MB Lierl, TJ Fischer, K O'Brien, J Cross, C Steinmentz. Latex allergy in hospital employees. Annals of Allergy 1994 72: 245-9.
  4. A Rosen, D Issacson, M Brady, JP Corey. Hypersensitivity to latex in health care workers: report of five cases. Head & Neck Surgery 1993 109: 731-4.
  5. PI Ellsworth, PA Merguerian, RB Klein, AA Rozycki. Evaluation and risk factors of latex allergy in spinal bifida patients: is it preventable? Journal of Urology 1993 150: 691-3.
  6. LL Tosi, JE Slater, C Shaer, LA Mostello. Latex allergy in spina bifida patients: prevalence and surgical implications. Journal of Paediatric Orthopaedics 1993 13: 709-12.
  7. ML Pearson, JS Cole, WR Jarvis. How common is latex allergy? A survey of children with myelodysplasia. Developmental Medicine and Child Neurology 1994 36: 64-9.
  8. D-A Moneret-Vautrin, E Beaudoin, S Widemer, C Mouton, G Kanny, F Prestat, C Kohler, L Feldmann. Prospective study of risk factors in natural rubber latex hypersensitivity. Journal of Allergy and Clinical Immunology 1993 92: 668-77.



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