Natural rubber latex allergy in children who had not undergone surgery and children who had undergone multiple operations

Latex Allergy: Where Are We Now and How Did We Get There?

Latex allergy emerged as an epidemic of anaphylaxis, occupational asthma, and clinical dilemmas in the 1980s. A systematic recognition, investigation, discovery, epidemiology, and prevention strategy followed. International attention and collaborations of investigators, government agencies, manufacturing, and health policy resulted in near elimination of a global epidemic. This article summarizes nearly 4 decades of work in control of this epidemic and focuses attention on future problems that still require resolution.

Latex allergy in children: modalities and prevention

Allergic or immediate hypersensitivity reactions to latex have been reported in children with increasing frequency in the past. The reported prevalence varies greatly depending upon the population studied and the methods used to detect sensitization. Children's subpopulations at particular risk include: atopics, individuals with spina bifida, children undergoing surgical procedure during the neonatal period and individuals who required frequent surgical instrumentations. Latex allergy is also an important medical issue, particularly for healthcare personnel. Sensitization mainly occurs by wound or mucosal contact with latex devices during surgery or by inhalation of airborne allergens released from powdered latex gloves. Regarding diagnosis, the medical history, skin prick test and search for specific serum IgE are crucial but cost effective. The development of a guide listing latex-containing drugs is essential for the primary prevention of allergic reactions. Immunotherapy or specific premedication seems not effective in preventing the risk of anaphylaxis during the perioperative course. The most effective strategy to decrease the incidence of latex sensitization is complete avoidance. This strategy is efficient in patients and also in health care workers and has been applied since 2002 in our pediatric surgical hospital. One of major problem with the latex-free gloves was that surgeons find them considerably more difficult to work with. But today, manufacturers made considerable effort and free-latex gloves with an equal tactile sensation than the latex-gloves are now available. The extra cost of free latex gloves is well counterbalanced as allergen test, long stay hospital for allergic reaction, and worker's compensation are no longer needed. Since the introduction of this program in our institution, no allergic reaction to latex has been reported in 25000 anesthetized children or with the health care workers.

The prevalence of latex allergy in sixth-year medical students: assessment of knowledge, risk, and attitudes about future specialty direction

BACKGROUND

In the prevention of latex allergy, knowledge levels and risk determination for latex allergy of medical students gain importance.

OBJECTIVES

To evaluate the latex allergy knowledge levels of sixth-year medical students and their latex allergy risk.

METHODS

Students completed a questionnaire that assessed basic knowledge of latex allergy and that evaluated latex-related symptoms and latex exposure. The specialty branch students were going to choose in the Medical Specialty Examination was also asked. Skin prick tests (SPTs) with latex and inhalant allergens and patch tests with latex-related products were then performed. Finally, students were asked again about any changes in branch selection after learning their individual risks.

RESULTS

Two hundred twenty sixth-year students were enrolled. Forty-four percent of the students gave the right answer for description of latex. Correct identification of at least 1 latex-related product used outside and inside hospitals was 55.5% and 95.5%, respectively. The prevalence of latex sensitization was 4.4% according to SPT results. The positivity of SPT to any inhalant allergen was 35% (n = 64). None of the students changed their mind about their specialty branch after learning their latex allergy risk.

CONCLUSIONS

Last-year medical students have a remarkably low latex allergy knowledge level, which imposes a serious professional risk. Training strategies based on the benefit to this risk group and reevaluation are strongly recommended before graduation from medical school.

Latex allergy: a model for therapy

Allergy to natural rubber latex products emerged as an important clinical condition following an increase in the use of latex gloves for barrier protection in the early 1980s. In addition to latex glove users, other high-risk groups with different latex exposure include spina bifida patients and others with multiple surgical procedures. Subjects with fruit and vegetable allergy are also at risk due to cross-reactive allergens. Following the significant advances in the identification and characterization of common aeroallergens, latex allergy was well placed to become an excellent model of therapy. Awareness of latex allergy and modes of sensitization enabled epidemiological studies to inform allergen avoidance initiatives, substantially reducing inadvertent exposure in major hospitals in Western countries. Spina bifida is often identified in utero or soon after birth, allowing vigorous latex allergen avoidance with enhanced efficacy of primary prevention. However, changing demographics of latex allergy and technological revolution in countries such as China and India are predicted to unleash a second wave of latex allergy reemphasizing the incentive for improved manufacturing procedures for latex products. The desirable high tensile strength and elasticity of natural rubber latex have made the commercial identification of good alternatives very difficult but this would also be attractive for primary prevention. In addition, an effective specific immunotherapy regimen would be valuable for selected high-risk atopic individuals. Current subcutaneous and sublingual immunotherapy schedules have been tested for treatment of latex allergy with evidence of efficacy but the risks of adverse events are high. For such potent allergens as latex, hypoallergenic but T cell-reactive preparations are required for clinical use. Identification of allergenic components of latex products, with generation of monoclonal antibodies and recombinant allergens, allowed sequence determination and mapping of T cell and B cell epitopes. Together, these reagents and data facilitated improved diagnostics and investigation of novel-specific therapeutics. Potential hypoallergenic latex preparations identified include modified non-IgE-reactive allergen molecules and short T cell epitope peptides. The co-administration of adjunct therapies such as anti-IgE or corticosteroids and of appropriate adjuvants for induction of regulatory T cell response offers promise for clinically effective, safe latex-specific vaccines.

Latex allergy, a special risk for patients of otorhinolaryngology and head and neck surgery?

A total of 206 patients of the otorhinolaryngology (ORL) department and 204 of the visceral surgery department of the Ludwig Maximilians University of Munich were preoperatively evaluated for latex-specific sensitization. A prick test, a questionnaire, and an enzyme-linked immunosorbent assay immunoprecipitation for IgE antibodies were performed. Latex is a widely spread allergen, and it does not only concern healthcare populations. Within the ORL surgery group, 43 (20.9%) patients were sensitized against latex allergen, and 2 of them were reported to manifest symptoms in consorting with latex. In the cohort of visceral surgery patients, we detected only 23 patients (11.3%) with sensitization against latex. Moreover, most patients were positively detected with the skin prick test (86.4%), whereas the enzyme-linked immunosorbent assay method was less sensitive (18.3%). Patients of the ORL department were considerably more frequently exposed to latex protein particles than patients of the visceral surgery department. This difference attributes to their significant difference in mean age: 44 years in the ORL patients group versus 58 years in the visceral patients cohort. Furthermore, we did not find any correlation to the number of past operations--although undergoing any surgical procedures is a well-known risk factor in other studies about latex sensitization in surgical patients.

Prevalence of latex sensitization and allergy in Portuguese children

The prevalence of latex allergy has been increasing not only in risk groups but also in the general population, where it is accepted to average 1%. In children, latex sensitization prevalence studies are scarce and involve different population sampling and allergy testing methods, which makes it difficult to compare across studies. Nevertheless, existing studies point towards a low prevalence of latex allergy in children, which still needs to be confirmed in the Portuguese population. Aiming at studying the prevalence of latex sensitization and allergy in a sample of Portuguese children, we studied 182 children from two different hospital outpatient clinics. A standardized questionnaire focusing on atopic background, previous history and allergic signs or symptoms on exposure to latex or fruits was given to all children and parents. Skin prick testing was performed with a battery of common aeroallergens as well as latex. Serum total IgE, Phadiatop, F x 5E and latex-specific IgE were determined in all children. Specific IgE to latex-crossreacting fruits was determined in latex-sensitized children. Based upon the questionnaire, the prevalence of latex allergy would be 0.5%. The prevalence of latex sensitization would be 3.8%, when based solely upon skin prick testing, and 12.1% (>/=0.35 IU/ml) or 6.6% (>/=0.70 IU/ml) when based singly upon determination of latex-specific IgE. When positive results for either test were considered, the prevalence of latex sensitization was 14.3%. All latex-sensitized children were atopic. Sensitivity to latex-crossreacting foodstuffs was demonstrated in 61.5% of latex-sensitized children (16/26). This study shows that the prevalence of latex allergy and sensitization in Portuguese atopic and non-atopic children, as analysed using various diagnostic methods, is similar to that observed in other countries. In addition, the assessment of latex allergy and sensitization should always include skin prick testing and determination of serum IgE.

Basophil Activation Test and specific IgE measurements using a panel of recombinant natural rubber latex allergens to determine the latex allergen sensitization profile in children

There are no documented studies that describe natural rubber latex (NRL) sensitization in children with a history of surgical intervention but without any congenital malformation (urogenital anomalies, spina bifida, etc.), although some authors have studied NRL allergy in children without a history of surgical intervention. The aim of this work was to evaluate the sensitization profile to single NRL allergens in children without spina bifida and without repeated surgical interventions, by using different recombinant and natural latex allergens in two analytical techniques: specific serum immunoglobulin E (IgE) quantification and flow cytometry determination of activated basophils expressing CD63, after stimulating cells from patients with NRL allergens. A total of 23 patients and 10 healthy children were selected. Conjunctival and in-use NRL provocation tests were carried out, as well as specific IgE determination in all patients' and controls' sera with the recombinant NRL allergens: rHev b 1, rHev b 2, rHev b 3, rHev b 5, rHev b 6.01, rHev b 6.02, rHev b 8, rHev b 9 and rHev b 11 and with NRL (k82) using appropriate ImmunoCAPs. The Basophil Activation Test (BAT) was performed with whole latex extract and with the recombinant allergens rHev b 5 and rHev b 6.01, as well as with the natural allergen Hev b 6.02. The sensitivity and the specificity of NRL-specific IgE (k82) were 100%. Positive IgE responses to rHev b 5 were found in sera of 10 children, to rHev b 6.01 in 16 and for rHev b 6.02 in 15 children's sera. Specific IgE to rHev b 8 was found in four sera of the children. We only found significant differences in sensitization to rHev b 5 in children with two or more surgical interventions compared with the non-intervened group or those with only one intervention. Specific IgE in sera of children with latex-fruit syndrome recognized rHev b 6.02, but not to rHev b 11. The patients sensitized to Hev b 8, Hev b 9 and/or Hev b 11 were atopic. The four patients presenting a positive response to the NRL profilin Hev b 8 were allergic to pollen. The BAT against whole NRL extract was positive in 22 of 23 children; against rHev b 5 in 14 of the patients studied; against rHev b 6.01 in seven cases and against nHev b 6.02 in 19 children. In all the control subjects, the results using this technique were negative. If combined rHev b 5, rHev b 6.01 and nHev b 6.02 together, BAT could detect 20 of the 23 children with latex allergy. The combined use of ImmunoCAP with all the recombinant NRL allergens and BAT with rHev b 5, rHev b 6.01 and nHev b 6.02, enabled the identification of NRL allergy in 22 of 23 patients. There is a positive and significant correlation between sensitization to Hev b 5 and the number of interventions. BAT and allergen-specific IgE determination could be used as first-line in vitro diagnostic tests in patients with NRL allergy.

Latex allergy in children: a follow-up study

BACKGROUND

Natural rubber latex allergy is an important health problem. Multiple contacts with latex in childhood are a risk factor. Many aspects of this disease are still unknown, one of which is the clinical outcome of these children. The aim of this study was to evaluate the clinical and epidemiological features of latex allergy and compliance with latex avoidance instructions in allergic children.

MATERIAL AND METHODS

Seventeen consecutive patients with a history of latex allergy, fruit allergy or chronic urticaria were selected. The patients underwent a skin prick test and determination of specific-IgE to latex at the start and at end of the study (median follow-up: 3 years). At diagnosis, patients with a positive result to one of the tests and a clinical history of latex allergy were considered allergic; patients with a positive test but without a clinical history suggestive of allergy were considered sensitized. These children were given latex avoidance instructions.

RESULTS

Eleven children (64.7 %) were classified as allergic and 6 (35.3 %) as sensitized. Five patients had undergone latex-free surgery after diagnosis without incident. During follow-up, 11 patients (8 allergic and 3 sensitized) had contact with latex. Contact occurred in the home in 10 children, and all were symptomatic. Specific-IgE levels to latex at the end of the study were significantly higher in patients who had contact with latex during the follow-up period than in those without latex contact.

CONCLUSIONS

Strict compliance with latex avoidance instructions is essential both inside and outside the hospital. Greater emphasis should be placed on reducing latex exposure in the home and school environments, as such contact could maintain positive IgE-antibody levels.

Anaphylaxis: Drug Allergy, Insect Stings, and Latex

The highest rates of anaphylaxis in humans occur in early childhood associated with food allergy. Latex allergy, pharmaceutical drugs, and stinging insect reactions are important later in childhood, with drug allergy peaking in adult populations. Knowledge about diagnosis and therapy of anaphylaxis is critical, because a large percentage of subjects are not previously known to be at risk at the time of initial reactions. This article summarizes the basic clinical knowledge of anaphylaxis in childhood.

Role of cross-allergies to latex in clinical routine of anesthesia

STUDY OBJECTIVE

To determine the applicability and reliability of a screening questionnaire to detect patients at high-risk of latex allergy; to assess the importance of other allergies such as profilin allergies (pollinosis) for presence of latex sensitization; and to determine the clinical effectiveness of preemptive avoidance of latex exposure in high-risk patients.

DESIGN

Prospective, clinical trial.

SETTING

Operative theater of a university hospital.

PATIENTS

95 adult patients.

INTERVENTIONS

Patients were preoperatively screened and classified for present latex allergy (high-risk and low-risk group) according to a specially designed screening questionnaire. Anesthesia and surgery in the high-risk group were performed strictly avoiding latex-containing materials. The low-risk group (other allergies including pollinosis) received routine treatment, without latex-avoidance. Effects of latex avoidance or exposure were evaluated by measuring specific IgE titers perioperatively.

MEASUREMENTS AND MAIN RESULTS

According to the questionnaire, 45 patients at high risk were defined. Validity of classification of high-risk patients is supported by significantly higher total IgE and latex and grass profilin specific IgE compared to the low-risk group. There were no significant differences in other profilin-specific IgEs. In one case of severe anaphylactic reaction a drop of latex-specific IgE during surgery could be observed.

CONCLUSION

The questionnaire allowed the identification of most patients at high risk for latex allergy. In isolated pollinosis no changes in any specific IgE levels were detectable. Strict avoidance of perioperative latex exposure in high-risk patients increases safety during anesthesia and surgery.

[Latex allergy in children]

The aim of our study was to determine the prevalence of latex allergy and the clinical features of children with latex allergy.

PATIENTS AND METHODS

We prospectively investigated 243 children consulting in our allergy out-patients unit during 1 year. Parents answered a questionnaire, and children underwent skin prick tests with common allergens and latex. Latex-specific serum immunoglobulin E was determined by CAP test in children with latex sensitization. The results were compared in children with and without latex allergy.

RESULTS

The prevalence of latex allergy was 1.3%. A family history of atopy (75%) and a personal history of previous surgery was associated with latex allergy (P < 0.0001). In children with latex allergy, the frequency of sensitization to inhaled and food allergens, atopic dermatitis, rhinitis and conjunctivitis was higher than in children without latex allergy (P < 0.05). Avocado allergy was the food allergy most commonly associated with clinical symptoms. Balloon was the most common latex product causing symptoms (60%).

CONCLUSIONS

Due to its potential severe consequences, latex allergy should be investigated in children who had undergone multiple surgical procedures and in the children with pollen-food allergy syndrome. Avoidance of latex is an important preventive measure.

Transdermal Xenobiotics in Newborn Skin

Newborn infants are regularly exposed to a wide variety of topical agents, including treatments for rashes, antimicrobial agents, solvents, and skin barriers or moisturizers. Premature and hospitalized infants are also exposed to topical iodine for antisepsis and to topical analgesic agents. The fact that most of these agents have not been specifically evaluated for use in infants has recently been recognized as a major public health concern. The epidermis of preterm infants is not fully developed, constituting an incomplete barrier to systemic absorption of topical agents. Thus, substances applied to the skin can have adverse systemic effects. Povidone-iodine and steroid creams have been associated with thyroid and hypothalamic-pituitary axis suppression, respectively, in premature infants. Application of topical EMLA (Eutectic Mixture of Local Anesthetics) for analgesia has been implicated in methemoglobinemia in premature infants. Exposure to natural latex in gloves and medical equipment may sensitize infants, leading to the development of airway hyperreactivity and other allergic manifestations. Therefore, it is advisable to limit skin exposure of premature infants to xenobiotics. Further work is required to define safe doses of common agents. In addition, transdermal administration of systemic medications, including methylxanthines, may be practical in premature infants.

Allergic and latex-specific sensitization: route, frequency, and amount of exposure that are required to initiate IgE production

Quantitative data that documents human exposure-response relationships for IgE sensitization to allergens are limited. Although seemingly straightforward, documentation of exposure-response relationships can be difficult. Issues that are related to study design, allergen standardization, exposure assessment, and evaluation for sensitization can impact greatly on study results. Despite these issues, exposure-response relationships for sensitization to protein allergens have been documented in several occupational groups, which include enzyme-detergent workers, bakers, and laboratory animal workers. In general, atopy acts as an effect modifier in these settings, steepening the exposure-response relationship. Several studies suggest that the greatest risk for sensitization is within the first several years of exposure. For 1 allergen, the protease subtilisin, a short-term exposure limit of 60 ng/m(3) has been recommended by the American Council of Governmental Industrial Hygienists. With regard to natural rubber latex, exposure-related factors such as number of operations have been shown to be risk factors for sensitization of children with spina bifida. By contrast, fewer studies show exposure-response relationships for IgE sensitization of health care workers to natural rubber latex, and the area remains controversial. However, a recent cohort study that evaluated incident sensitization in dental hygiene students suggests strongly that, with sufficient exposure, employment in health care can lead to an increased risk of IgE sensitization to natural rubber latex.

Outcome of a latex avoidance program in a high-risk population for latex allergy - a five-year follow-up study

BACKGROUND

Children with a shunted hydrocephalus are at highest risk for developing an immediate type allergy to latex. Limited data are available for preventive or therapeutical approaches.

OBJECTIVE

To evaluate the effectiveness of latex avoidance, with special regard to status of sensitization and compliance.

METHODS

In 1995, 131 children with a shunted hydrocephalus were screened for sensitization to latex by skin prick test and determination of specific IgE. Patients and parents were instructed on latex-avoiding strategies. Hospital physicians, family doctors and dentists were advised to perform further surgical and other medical interventions under latex-free conditions. In 2000, 100 of these 131 patients were re-evaluated according to the same testing procedures. Special attention was directed at the extent prophylaxis had been performed.

RESULTS

In 1995, 30/100 patients re-evaluable in 2000 proved sensitized to latex, 70 had negative testing results. In 2000, 64/70 patients were still negative, six had meanwhile developed latex-specific IgE. Seven out of thirty subjects with former positive testing had changes within the same RAST-class, 20 showed a decline of at least one RAST-class, whereas in three cases an increase of latex-specific IgE was found. However, only 34 patients, mainly those being already sensitized, had thoroughly followed both medical and private prophylaxis. Within this group, 16 subjects (47.1%) had improved and another nine (26.5%) were still negative. Only three (8.8%) already previously sensitized patients presented with a further increase of latex-specific IgE. Medical prevention contributed more to the outcome than home prevention. No statistically significant correlation with latex-avoidance was observed, however, in previously unsensitized subjects. Underlying disease, atopy, number of operations, and age did not prove as significant variables.

CONCLUSION

Secondary prevention results in a decrease of specific IgE in latex-sensitized patients with hydrocephalus. This is due to medical more than home prophylaxis. Sensitization obviously occurs mainly in early childhood, thus primary prevention remains to be the main target.

Latex allergy: prevalence, risk factors, and cross-reactivity

There are few little exact epidemiological data on the prevalence and incidence of latex allergy, partly because the diagnostic tools are unsatisfactory and partly because the epidemiological study planning often does not fulfill criteria of good praxis. On the basis of present data, latex allergy in normal population is low, under 1%. Known risk groups such as health care workers, atopic subjects, people with hand dermatitis, and especially spina bifida patients show higher prevalence numbers. The common serological cross-reactivity between latex and a great number of different fruits and vegetables is bound to common plant pathogenesis-related proteins and storage proteins. Despite positive serological tests, only about half of NRL-allergic subjects have clinical symptoms after eating cross-reacting foods.

Latex allergy: historical perspective

The widespread use of powdered latex gloves, following the institution of universal precautions in 1987, increased the occurrence of a host of adverse reactions to natural rubber latex (NRL). Although the most common reactions are irritant or allergic dermatitis reactions to manufacturing chemicals, a spectrum of type I IgE-mediated reactions to NRL proteins are of great concern. IgE-mediated reactions range from contact urticaria to occupational asthma and anaphylaxis, resulting in significant morbidity and potential mortality. At-risk populations include highly exposed groups like health care workers and certain patient groups requiring extensive medical treatment. A significant complicating factor is the association with clinically significant adverse reactions to certain foods because of allergen cross-reactivity. Institution of policies to use only low-protein, powder-free gloves, has resulted in a dramatic reduction of visits to occupational health departments and workmen's compensation claims due to occupational asthma.

[Peculiarities of latex allergy and preventive measures in the pediatric age group]

Latex allergy can be considered a problem of public health in at-risk populations. Although the figures on prevalence vary, approximately 1 % of the general population is sensitized to latex. To date, two determining factors for latex sensitization have been identified: an atopic predisposition and the number of operations. Among atopic patients or those at-risk for allergy, the prevalence of latex sensitization is between 3 and 20 times higher than that among the general population. Nevertheless, the effect of this factor seems to be modulatory and the determining factor seems to be the number of operations that children have undergone; the critical number is 5-6 interventions, after which the probability of sensitization increases considerably.All children who have undergone multiple operations should be considered as being at-risk. Children with spina bifida are especially at-risk. The reasons for this are still a matter of debate: the disease itself has been postulated as a specific risk factor, although other, possible associated factors could be determinant in triggering latex sensitization (the presence of a ventricular-peritoneal shunt, age at which surgery was performed, type of operation, etc.). Children with spina bifida and latex allergy show considerable differences in type of allergic sensitization; these differences seem to result from the different route of sensitization and could explain the variations observed in the clinical manifestations between children and adults: children become sensitized mainly by direct contact between latex particles and blood vessels and open mucosae while in adults the process takes place transcutaneously or by inhalation of aerosol particles. Consequently, the most frequent manifestation in children is urticaria while contact dermatitis and respiratory symptoms predominate in adults. Studies performed with immunoblotting have confirmed that children have IgE that almost constantly recognize low molecular weight latex proteins (14, 15 and 27 Kd) while this finding is less frequent in adults.The preventive measures in the pediatric population focus on avoidance of latex, especially in hospitals. Today, latex is ubiquitous, making complete avoidance difficult. When necessary, and whenever a latex-free environment cannot be guaranteed, presurgical medication can be used, although its utility is debatable. Although further studies are required, specific immunotherapy is one therapeutic possibility that may in future be used in children with latex allergy.

Specific monoclonal antibodies and human immunoglobulin E show that Hev b 5 is an abundant allergen in high protein powdered latex gloves

BACKGROUND

Hev b 5 is a major latex allergen recognized predominantly by latex-allergic health care workers (HCWs). Recombinant Hev b 5 (rHev b 5) was previously expressed as a fusion protein with maltose binding protein (MBP), itself an immunogenic molecule; therefore non-fusion rHev b 5 is desirable. Moreover, standardized immunological assays for the detection of Hev b 5 are currently lacking and may have important implications for both allergen avoidance and diagnosis in latex allergy.

OBJECTIVES

To generate and use Hev b 5-specific mAbs to determine the relative abundance of Hev b 5 in different latex extracts, correlating this with the IgE reactivity of latex-allergic HCWs and to produce non-fusion rHev b 5.

METHODS

For the production of mAbs, mice were immunized with rHev b 5/MBP fusion protein and mAbs selected with rHev b 5/MBP but not MBP reactivity. The mAb reactivity was compared with polyclonal IgE from latex-allergic HCWs using direct and inhibition ELISA and immunoblot assays. Recombinant Hev b 5 was expressed and purified in the pPROEX-HTa bacterial expression system.

RESULTS

Four Hev b 5-specific mAbs were produced. Immunoblotting and ELISA using the mAbs indicate abundant Hev b 5 in high protein powdered latex glove extracts as compared with crude latex sap extracts. High quality surgical gloves with no detectable protein have no detectable Hev b 5. Inhibition ELISAs using serum IgE from latex-allergic HCWs and Hev b 5-specific mAbs gave strong correlation. Non-fusion recombinant Hev b 5 was successfully expressed and purified, showing reactivity with both the Hev b 5-specific mAbs and serum IgE of latex-allergic HCWs.

CONCLUSION

Hev b 5-specific mAbs and human IgE from latex-allergic HCWs demonstrate the greater content of Hev b 5 in high protein powdered glove extracts. This may explain the observed higher frequency of sensitization to this allergen in HCWs.

Latex allergy: past and present

Although latex products have been in use for over a century, allergic responses to latex proteins have only been recognized as a serious health problem for the past 15 years. Latex allergy particularly affects two groups, health care workers (HCW) and children with spina bifida (SB). This manuscript provides a brief history of latex allergy, and a review of the following: the manufacturing process for dipped latex products, the 11 latex allergens that have been characterized and received allergen designations by the International Union of Immunological Societies, the methods used in exposure assessment, the epidemiology and clinical management of latex allergy, and the use of animal models in investigating mechanisms underlying latex allergy.

Natural rubber latex allergy after 12 years: recommendations and perspectives

Natural rubber latex (NRL) allergy is a "new" illness whose prevalence reached epidemic proportions in highly exposed populations during the last decade. In children with spina bifida and in patients exposed to NRL during radiologic procedures, institution of prophylactic safety measures has had demonstrable effects in preventing allergic reactions. The risk of NRL allergy appears to be largely linked to occupational exposure, and NRL-associated occupational asthma is due almost solely to powdered latex glove use. Prevalence of NRL-allergic sensitization in the general population is quite low; several studies of young adults demonstrate rates of positive skin test results that are less than 1%. After occupational exposure, rates of sensitization and NRL-induced asthma rise dramatically in individuals using powdered NRL gloves but not in individuals using powder-free gloves. Airborne NRL is dependent on the use of powdered NRL gloves; conversion to non-NRL or nonpowdered NRL substitutes results in predictable rapid disappearance of detectable levels of aeroallergen. For these reasons, adoption of the following institutional policies designed to prevent new cases of NRL allergy and maximize safety is recommended: (1) NRL gloves should be used only as mandated by accepted Standard Precautions; (2) only nonpowdered, nonsterile NRL gloves should be used; and (3) nonpowdered, sterile NRL gloves are preferred for use. Low-protein powdered, sterile gloves may be used, but only in conjunction with an ongoing assessment for development of allergic reactions.

Alergia látex-fruta

O látex está sendo considerado o alergênico do ano 2000, tendo em vista que inúmeros indivíduos, principalmente profissionais da área de saúde e pacientes submetidos a várias intervenções diagnósticas e terapêuticas, estão freqüentemente expostos aos alérgenos do látex, presentes em produtos de borracha natural. As manifestações clínicas conseqüentes às reações alérgicas de hipersensibilidade imediata vão desde rinite, urticária, conjuntivite, angioedema, asma, até anafilaxia. Estudos recentes estão demonstrando que pacientes alérgicos ao látex desenvolvem concomitantemente sensibilização a certos alimentos de origem vegetal, especialmente frutas como papaia, figo, banana, abacate, kiwi, pêssego, abacaxi, melão e castanha, acreditando-se numa provável ocorrência de reações cruzadas entre os alérgenos do látex e destas frutas. Faz-se, então, uma revisão sobre a alergia ao látex, em particular sobre os grupos de risco, incluindo a presença de reatividade cruzada entre o látex e as frutas.

Frequency of natural rubber latex allergy in adults is increased after multiple operative procedures

BACKGROUND

It has been shown that immediate-type allergy to natural rubber latex (NRL) affects predominantly health-care workers and infants with malformations requiring repeated medical procedures. Adult patients with multiple invasive procedures are not thought to be at an increased risk of NRL allergy.

METHODS

A total of 325 consecutive adult inpatients (54.4+/-15.6 years; 219 men, 106 women) awaiting surgical or urologic procedures were assessed by questionnaire-based history (atopic diseases, number of previous standard operative or endoscopic procedures, intolerance to rubber products, and adverse reactions during medical care), by skin prick tests with different NRL test solutions, by measurement of NRL-specific IgE in the serum, and, if sensitization to NRL was found, by cutaneous challenge tests with NRL-containing material. Subjects were classified as sensitized to NRL if skin prick test reactions to NRL were positive or if NRL-specific IgE antibodies were found. NRL allergy was defined as NRL sensitization and immediate-type symptoms to NRL.

RESULTS

Thirty-one of 325 (9.5%) subjects were found to be sensitized to NRL, 14/285 (4.9%) by skin prick testing and 23/323 (7.1%) by NRL-specific IgE antibodies in the serum. Four individuals (1.2%) were diagnosed as having clinically manifest NRL allergy, and another 27 (8.3%) were sensitized to NRL without symptoms to date. The frequency of previous invasive procedures was zero in eight patients, up to 10 in 245, 11-20 in 52, 21-30 in seven, and over 30 (up to 83) in 13 patients. No association was found between the number of invasive procedures and NRL sensitization without clinical symptoms. However, 3/4 patients with NRL allergy had undergone more than 30 interventions, and 1/4 had had 11 operations. Frequent invasive procedures (more than 10) were significantly associated with NRL allergy (P<0.001). Allergy or sensitization to NRL was associated with atopy (21/31 vs 87/294) (P<0.001).

CONCLUSIONS

A remarkable percentage of unselected adult patients undergoing surgical procedures have allergy or sensitization to NRL. Repeated invasive treatment appears to be a risk factor for NRL allergy.

Latex hypersensitivity in spinal cord injured adult patients

Latex hypersensitivity is a major cause of anaphylaxis during anaesthesia. Patients with spina bifida, health care or rubber industry workers have been considered at risk for latex sensitization. By analogy, the existence of other at-risk subsets of patients with latex exposure due to frequent surgical procedures has been suggested. The aim of this study was to evaluate the prevalence of latex sensitization in a cohort of adult patients with spinal cord injury and repeated latex exposure. Forty-two adult patients with spinal cord injury were studied and retrospectively compared to a group of 30 children with spina bifida evaluated using a similar protocol. Patients were administered a questionnaire concerning history of latex hypersensitivity, atopy, and surgical procedures. Latex sensitivity was investigated by skin prick-tests and latex-specific IgE assay. The search for atopy was based on in vivo and in vitro tests against a panel of environmental allergens. No chronic spinal cord injured patient had a history of latex allergy. When compared with spina bifida, the number of surgical procedures was not statistically different. Although not significantly different, the prevalence of atopy was higher in spina bifida patients. The high level of latex sensitization in spina bifida patients contrasted sharply with the absence of sensitization observed on both skin and in vitro tests in patients with spinal cord injury (P<0.0001). This study confirms that adult patients with chronic neurologic defects resulting from spinal cord injury exhibit a low risk of latex sensitization. These results suggest that considering adult patients with repeated surgical procedures as a group at risk for latex sensitization because of a high degree of latex exposure should be re-examined.

Latex allergy: review of recent advances

Latex allergy is an IgE-dependent immediate hypersensitivity reaction to latex proteins. Risk factors for latex allergy are contact with latex products and atopy. Children who undergo multiple surgical procedures and healthcare workers are the major groups at risk. Powdered latex gloves are an important source of sensitization. Preventive measures are leading to reduction in latex sensitization and allergic reactions. The prevalence of latex allergy in the general population may be as low as 0.1%, whereas the frequency of latex sensitization is reported to be 7%; this may be due to cross-reacting antipollen IgE. The most important latex allergens have been purified, and some have been cloned and sequenced. Many latex-allergic patients are also allergic to common plant-derived aeroallergens and foods. The structural and biologic relationships among plant-derived food allergens, including latex, explain these clinically important cross-reactions.

Natural rubber latex allergy in children: a follow-up study

BACKGROUND

Natural rubber latex (NRL) allergy occurs frequently in children with spina bifida and other children with disorders requiring multiple operations. Also atopic children who have not undergone surgery can be sensitized to NRL, but the outcome of these children has not been studied.

OBJECTIVE

To study how NRL-allergic children manage at home and whether their skin prick test (SPT) reactivity, latex RAST or IgE antibody levels to NRL allergens change during the follow-up.

METHODS

Twenty-four NRL-allergic children who had not undergone surgery and eight children with histories of multiple operations were followed up for a mean of 2.8 years. Clinical symptoms were recorded and all children were re-examined with SPT, latex RAST and ELISA for IgE antibodies to prohevein (Hev b 6.01), hevein (Hev b 6.02) and rubber elongation factor (REF, Hev b 1).

RESULTS

Nineteen of the 24 NRL-allergic children (79%) who had not undergone surgery had occasionally contacts to balloons and other NRL products at home, and 10 of them experienced symptoms ranging from contact urticaria to systemic reactions. Three of the eight NRL-allergic children with a history of multiple operations had contacts to rubber balloons without any symptoms, and five children underwent 1-8 uneventful operations in a latex-free environment. SPT reactivity to NRL allergens, latex-RAST or IgE antibody levels to prohevein or hevein did not change in either group of NRL-allergic children during the follow-up.

CONCLUSIONS

Occurrence of clinical symptoms and no decrease in SPT reactivity or IgE levels to NRL allergens in the course of the present follow-up study imply that more attention should be paid to the protection of NRL-allergic children from rubber contacts in the home environment.

Natural rubber latex: glove use, sensitization, and airborne and latent dust concentrations at a Denver hospital

Exposure to natural rubber latex may cause immediate hypersensitivity reactions. Published latex sensitization prevalence rates range from 2.9% to 22% among health care workers, and from 0.12% to about 20% of occupationally unexposed populations. In this study, self-administered questionnaires addressed job and personal characteristics, glove use, and symptoms in two groups of hospital workers: those who regularly used latex gloves and those who did not. Serum was tested for latex-specific immunoglobulin E. Air, surface, and air-filter dust samples for natural rubber latex were collected. The prevalence of latex sensitization was 6.3% in the non-users and 6.1% in the latex glove users (P = 0.9); 81.3% of sensitized workers were atopic compared with 59.5% of non-sensitized workers (P < 0.05). Reporting of work-related hand dermatitis was more common in the latex glove users (23.4%) than in the non-users (4.9%), as were rhino-conjunctivitis (16.3% and 7.9%, respectively, [P < 0.01]), and hand urticaria (9.9% and 2.1%, respectively, [P < 0.01]). There was no significant difference in work-related symptoms between the sensitized and non-sensitized workers. Environmental concentrations of latex were higher in the work areas of the non-sensitized workers, but higher in the clinical than in the non-clinical areas. Occupational latex glove use was not a risk factor for sensitization.

The occupational hazards of emergency physicians

Emergency physicians are exposed to a variety of occupational hazards. Among these are infectious diseases, such the human immunodeficiency virus, hepatitis B and C viruses, and tuberculosis. Hepatitis G virus is transmissible but may not be a cause of illness. The likelihood of being exposed to these agents appears to be higher in the ED than other medical settings but estimates of the prevalence of these diseases in the ED vary, depending on the patient population served. Estimates of risk for contracting these infections are reviewed. Measures to prevent these exposures can reduce risk, but compliance is low, particularly for those involving changes in the behavior of emergency physicians (such as not recapping needles). Latex allergy is a hazard of health care workers. Its prevalence is reported to be quite high, but these findings are difficult to interpret in the absence of a universally accepted definition of the condition. Its prevalence in emergency physicians is not known. Other noninfectious hazards include workplace violence and exposure to nitrous oxide. The health effects of rotating shift work may put emergency physicians at increased risk of coronary artery disease and impaired reproductive health. Emotional stress is another hazard of emergency physicians, and may lead to burnout.

IgE reactivity to patatin-like latex allergen, Hev b 7, and to patatin of potato tuber, Sol t 1, in adults and children allergic to natural rubber latex

BACKGROUND

Patients allergic to natural rubber latex (NRL) frequently show positive skin prick tests (SPT) and hypersensitivity reactions to various fruits, such as avocado, banana, and kiwi, as well as to vegetables such as potato.

METHODS

Hev b 7 was purified from NRL "C-serum" and Sol t 1 from potato extract, and they were detected by immunoblotting. IgE antibodies to Hev b 7 and Sol t 1 were measured with ELISA in sera from 35 adults and 35 children allergic to NRL. ELISA inhibition and immunoblotting were used to study allergen cross-reactivity. The in vivo reactivity of Hev b 7 and Sol t 1 were demonstrated in the SPT.

RESULTS

Seventeen (49%) of the 35 NRL-allergic adults had IgE antibodies to Hev b 7, in contrast to only one of the 35 NRL-allergic children. Fifteen (43%) of the NRL-allergic adults and 29 (83%) of the NRL-allergic children had IgE antibodies to Sol t 1. Ten (29%) of the adult sera showed IgE binding to both Sol t 1 and Hev b 7, and crosswise inhibition tests with pooled sera revealed marked cross-reactivity. In the SPT, both natural Hev b 7 and Sol t 1 were able to produce a wheal and flare reaction.

CONCLUSIONS

One-half of the NRL-allergic adults, but only one of the NRL-allergic children, had IgE antibodies to natural Hev b 7. These results suggest that Hev b 7 is an important NRL allergen for adults, but not for children. Elucidation of the clinical importance of the observed cross-reactivity between Hev b 7 and Sol t 1 requires further studies.

Prevalence of IgE to natural rubber latex in unselected blood donors and performance characteristics of AlaSTAT testing

BACKGROUND

The prevalence of IgE to natural rubber latex (NRL) proteins in the general population remains unsettled, both because of the difficulty of obtaining an unbiased population representative of the general population of the United States and because of concerns about the reproducibility of tests for anti-latex IgE antibodies. Establishing the prevalence in the population is important toward defining the potential risks of persons entering areas where latex exposure may occur.

OBJECTIVE

The purposes of this study were to determine the prevalence of IgE to latex in a general population and to assess the performance characteristics of the AlaSTAT microtiter plate test for anti-latex IgE when performed independently by different laboratories.

METHODS

One thousand nine hundred and ninety-seven consecutive blood samples obtained from the Oklahoma Blood Institute were assayed independently in three laboratories for IgE to NRL using the FDA-approved AlaSTAT ELISA for IgE to NRL. The group consisted of 56% men and 44% women. Ninety percent were Caucasian, 4% African American, and 6% were "other."

RESULTS

The prevalence IgE to NRL between the 3 laboratories varied from 5.4% to 7.6% at the designated cut off of 0.35 kU/L. Examination of results for specific individuals demonstrated >90% agreement between the three sites with the most reproducible results at the Class II cutoff of > or =0.7 kU/L. There was no difference in the percent of positive values at the three laboratories.

CONCLUSIONS

There is good agreement between laboratories as to NRL IgE reactive and non-reactive sera using the AlaSTAT test. This report of the largest sample of blood donors confirms earlier reports as to the prevalence of IgE NRL in blood donors.

Latex allergy in subjects who had undergone multiple surgical procedures for bladder exstrophy: relationship with clinical intervention and atopic diseases

OBJECTIVE

To evaluate the prevalence of latex sensitization in a group of patients with bladder exstrophy, and to determine the role of associated risk factors, e.g. atopy, and the number and duration of surgical and anaesthetic procedures.

PATIENTS AND METHODS

The study comprised 17 patients (15 children and two young adults) affected by bladder exstrophy who had undergone multiple surgical procedures. Skin-prick tests and specific immunoglobulin-E (IgE) assays against latex, food allergens cross-reacting with latex and inhalant allergens were carried out.

RESULTS

Twelve patients showed latex sensitization and five showed symptoms related to latex exposure, the most common of which was contact urticaria (four of the symptomatic patients). Intraoperative anaphylactic reaction had led to life-threatening events in only one child. Latex-specific IgE determined both by the prick test and assay was positive in all those with symptoms. Specific IgEs against inhalant allergens and foods were present in four of five symptomatic patients. In the seven sensitized patients with no clinical symptoms, the assay was positive in all, while the skin-prick test was positive only in four; specific IgEs against inhalant allergens were present in three of the seven. In the five patients not allergic and not latex-sensitized, only one showed allergic sensitization against grass pollen and mite allergen. None of the children without latex antibodies had symptoms of latex allergy. Symptomatic patients had a undergone significantly more hours of surgery, more cystography and had used intermittent catheterization for longer than those with no symptoms.

CONCLUSION

A third of patients with bladder exstrophy showed latex symptoms and another third had latex sensitization. Multiple surgical procedures and atopy play a major role in the development of latex hypersensitivity

Latex sensitization: occupational versus general population prevalence rates

BACKGROUND

Natural rubber latex (NRL) has become an important occupational health concern in recent years, particularly among health care workers. It has been suggested in some reports that the prevalence of latex sensitization among occupationally exposed groups is not different from that in the general population.

METHODS

The findings of prevalence studies conducted among occupationally-exposed and general population groups were reviewed to determine whether there is evidence to support this suggestion.

RESULTS

Numerous surveys of HCWs have demonstrated that the prevalence of sensitization to latex ranged in most studies from 5 to 12%; sensitization of HCWs may produce clinical effects including urticaria, rhinoconjunctivitis, occupational asthma, and potentially life-threatening anaphylactic shock. More than a decade ago, data from Finland indicated that the prevalence of latex allergy in the general population was less than 1%. Recent reports from Finland have confirmed this, with observations that 0.7-1.1% of large series of patients were NRL-allergic, while among 804 unselected patients, the prevalence of latex skin prick test (SPT) positivity was 0.12%. In contrast, other studies have suggested that from 4 to 6.4% of individuals tested were positive for serum latex-specific IgE antibodies. However, the specificity of these assays has been reported to be low. In three recent studies based on SPTs, published in 1997, the prevalence of positive reactions to latex was about 1% or less. The prevalence was 0.7% (95% CI 0.3-1.4) among 758 apprentices in Quebec, Canada; and 1.1% among more than 3,000 children tested in Finland (1.0% confirmed on latex use test). There were no first- and second-year dental students with positive latex SPTs in Ontario, Canada.

CONCLUSIONS

These recent investigations provide further evidence consistent with earlier studies based on skin testing that the prevalence of latex sensitization in occupationally-unexposed groups is quite low (< 1%). The marked differences in the findings based on serological assays may relate to the nonspecificity of these assays and deserve further investigation.

Anaesthesia for the allergic patient

Knowing that allergic reactions that occur during anaesthesia are essentially caused by muscle relaxants or latex, the patients who should be singled out during the preanaesthetic visit are those already allergic or thought to be allergic to these two substances. On the other hand, atopy or allergy to other drugs, such as antibiotics, has not been proved to favour the triggering of anaphylactic shocks with anaesthetic drugs. Allergy to local anaesthetics is so exceptional that it may be easily dismissed by a challenge test.