Seroprevalence of diphtheria immunity among injured adults in Austria

Over a period of 1 year a seroepidemiological study was conducted at the ou tpatient clinic of a trauma department. Immunity to diphtheria was determin ed in serum samples from 558 injured patients (205 women and 353 men, age f rom 18 to 70). Diphtheria-antitoxin concentrations were measured with an en zyme immunoassay and a tissue culture toxin-neutralization assay. Sere-immu nity was classified as susceptibility (< 0.01 IU/ml), basic protection (0.0 1- < 0.1 IU/ml) and full protection (greater than or equal to 0.1 IU/ml) ag ainst the toxic manifestations of the disease. A total of 27.1% of the subj ects were susceptible to diphtheria, 26.5% had basic protection, and 46.4% were fully protected. The median antitoxin concentration reached 0.08 IU/ml (0.0-0.29; quartiles Q25-Q75). A non linear trend toward decreasing immuni ty with increasing age was observed (P < 0.001) and females proved less pro tected than males (P = 0.006). The country of original immunization (Austri a, Western European countries, Eastern European countries and Non European countries) had no influence on sere-immunity (P = 0.49). Multiple linear re gression analysis revealed that age (P < 0.001) and gender (P = 0.004) had a significant independent influence on diphtheria immunity level, whereas t he country of original immunization was not significant (P = 0.72). (C) 200 0 Elsevier Science Ltd. All rights reserved.