Authors: Ratshikhopha M.E, Singh T.S, Lopata A.L, Jeebhay M.F
Source: Occupational Health Southern Africa 22(4); 8-14
Introduction: Accurate diagnosis of occupational latex allergy is important to clinically manage affected workers, implement exposure interventions, and prevent job change or job losses. Traditional immunological tests involve whole allergen extracts; however, newer diagnostic platforms use purified allergens and genetically engineered recombinant analogues.Allergen extracts are heterogeneous mixtures known to cross-react with proteins of other origins, complicating the identification of the primary allergen source.
Methodology: A total of 41 latex sensitised dental healthcare workers determined by ImmunoCap (k82) from a previous study (N=421) were included in this investigation. Demographic information and clinical and occupational histories were obtained through a self-administered health questionnaire. Eight recombinant allergens from Hevea brasiliensis (Hev b1, 3, 5, 6.01, 6.02, 8, 9 and 11) were used for the determination of specific IgE responses and two markers of cross reactive carbohydrate determinants (horseradish peroxidase (HRP), and bromelain (MUXF3)) was analysed with the Pharmacia ImmunoCap system, using sera from these workers. Frequencies of sensitisation were calculated for the various latex groups. Parametric analysis (anova), using log transformed data was applied to assess variation of the means between the various latex sensitivity categories.
Results: The prevalence of latex sensitisation in the study population was 9.7% (41/421). The mean age of the subjects was approximately 30 years. The majority of the k82-sensitised workers were non-smokers and females, whilst the oppositewas true for the k82-negative category, with 78% being ex-smokers and males. Eighty percent used gloves at work, of which a third was powdered latex gloves. Amongst those that were latex-sensitised, only 22 reported allergic symptoms (respiratory and or skin). Based on the Hev b allergen and CCD specific IgE (sIgE) levels, only about 50% (22/41) demonstrated true latex allergy which accounts for 5.2% of the initial total study population. Approximately 2% (7/421) hadasymptomatic latex sensitisation and 3% (12/421) accounted for false positive reactions.
Conclusion: Although composite latex k82 is efficient in demonstrating sensitisation in exposed individuals due to its highsensitivity, it lacks specificity. The use of component resolved diagnosis (CRD) provided a useful approach in confirming a latex allergy diagnosis. CRD adds value to allergy management through early identification of offending allergens, resulting in reduced severity of reactions and delayed disease progression.