Prevalence of sensitization to Dermatophagoides pteronyssinus in several industrial populations

Skin tests with Dermatophagoides pteronyssinus were carried out by the standard prick method in six groups of industrial workers: meat processing workers (n = 107), brewery workers (n = 96), animal food workers (n = 40), swine farmers (n = 32), paper-mill workers (n = 132) and wool-textile workers (n = 111). The control group consisted of 158 subjects who were tested during the preemployment examinations and had not worked in industrial plants before. Skin reactions were read after 20 minutes by measuring the largest urtica diameter in millimeters. A diameter >3 mm was considered to be a sign of a positive skin reaction. In relation to the control group a significant (P < 0.01) higher prevalence of positive skin reaction to D. pteronyssinus was found among the meat processing workers (41-13%, animals food workers (30 vs. 13%), swine farmers (34 vs. 13%) and wool-textile workers (32% vs. 13%). Results of the standard prick rest were not significant for the brewery workers (21 vs. 13%) and the paper-mill workers (21 vs. 13% in controls). Our results demonstrate the need for applying specific individual health measures if working conditions favour the growth and reproduction of house dust mites.