Abstract
BackgroundRecommendations for diphtheria immunization are to apply an effective primary immunization in infancy and to maintain immunity throughout life. Immunity against diphtheria depends primarily on antibody to the diphtheria toxin. This study evaluated the seroprevalence of IgG diphtheria antitoxin in sera of healthy children, adolescents and adults in Poland.MethodsA total of 1387 serum samples collected between 2010 and 2012 from individuals with ages ranging from 1 month to 85 years were investigated. Antibody concentrations were measured with an enzyme-linked immunosorbent assay (Anti-Diphtheria Toxoid ELISA IgG, Euroimmun, Germany).ResultsThe results showed that among 1387 individuals examined, 547 (39.4%) had anti-diphtheria toxoid IgG antibody levels below 0.1 IU/ml (36.9% ≤18 years and 40.5% >18 years old, respectively). The 212 (50.8%) children and 542 (55.9%) adults showed only basic protection (0.1-1.0 IU/ml) and need immediate booster. High levels of anti-diphtheria toxoid IgG antibodies (>1.0 IU/ml) were found more often in children and adolescent (12.2%) than in adults (3.6%) and this was statistically significant (P < 0.05). The proportion of seronegatives (< 0.1 IU/ml) in children below 2 years old, adolescents and young adults to 25 years old decreased from 53.5% to 17.4%. However, in older individuals the seronegative proportion tended to increase with age, from 22.7% in adults (26–30 years old) to 67.1% in subjects > 60 years old. Characteristically, in individuals > 40 years old high levels of anti-diphtheria toxoid IgG antibodies (>1.0 IU/ml) were not seen. There were no statistically significant differences in results in relation to gender.ConclusionsThe present study showed inadequate immunity levels to diphtheria amongst the Polish population, especially in adults > 40 years old and children ≤ 2 years old. To prevent reemergence of diphtheria an information campaign reminding people about recommendations concerning diphtheria booster vaccination in adults should be conducted. Moreover, the immunogenicity of the DTP vaccine used in Poland should be verified.
Highlights
Recommendations for diphtheria immunization are to apply an effective primary immunization in infancy and to maintain immunity throughout life
Among 1387 individuals examined, 547 (39.4%) had levels of anti-diphtheria toxoid IgG antibodies below 0.1 IU/ml (36.9% ≤ 18 years and 40.5% >18 years old, respectively)
This study showed that there is insufficient herd immunity to diphtheria in the Polish population which could potential lead to an epidemic
Summary
Recommendations for diphtheria immunization are to apply an effective primary immunization in infancy and to maintain immunity throughout life. Diphtheria is a severe and potentially fatal disease caused by toxin-producing strains of Corynebacterium diphtheriae, Corynebacterium ulcerans and Corynebacterium pseudotuberculosis. A large pool of susceptible persons creates an epidemic potential, as demonstrated by the last diphtheria epidemic that occurred in the early 1990s in the countries of the former Soviet Union when more than 50 000 cases were recorded at the peak of the epidemic. During this epidemic adolescents and adults were mainly affected, most of whom would have been previously vaccinated [4,5,6,7]. The reservoir hosts of this species are domestic cats and dogs [8,9]
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