Allergic sensitization in workers from a cocoa processing plant in Côte d’Ivoire

Introduction
In Côte d’Ivoire allergic diseases of undocumented origin have been observed in workers involved in the primary transformation of cocoa beans. We conducted a cross-sectional study of allergic sensitization to cocoa and possible allergic disease in a plant producing cocoa powder and butter.

Methods
Out of 231 employees, we enrolled 35 male workers with regular exposure to cocoa dust and 15 male (9) or female (6) administrative workers (controls) between March 2010 and January 2011. The subjects were administered a questionnaire; they underwent skin prick-tests with various aeroallergens, including with 0.1% suspensions of cocoa powder prepared from local samples; specific serum IgE to cocoa were determined by fluoro-enzyme-immuno-assay using reagents from Phadia. Personal dust sampling was performed with Air Check XR5000 pumps.

Results
Mean age was 39.5 y (SD 6.7) in controls and 37.8 y (SD 5.7) in exposed subjects; the two groups had similar mean employment durations (6.9 and 6.0 y, respectively). The prevalence of personal or familial signs of atopy was higher among controls (53%) than among exposed workers (9%). Dust levels ranged from 3.4 to 83.1 mg/m3 in the various workstations. None of the control subjects and only one exposed worker had a positive skin prick-test against the cocoa suspension. In contrast, none of the exposed workers had positive serum IgE against cocoa, but one control subject (with reported allergy to peanut and shrimp) had a positive IgE against cocoa (0.37 Ua/ml).

Discussion
This cross-sectional study does not indicate a higher prevalence of sensitization to cocoa among exposed workers than among administrative workers from the same plant. We found discordant results between the findings obtained using a custom-made skin prick-test against cocoa and serum IgE against cocoa, as determined by a commercial assay. These preliminary findings should be verified by a larger longitudinal study.