Epidemiology and Infection



The sero-epidemiology of diphtheria in Western Europe


W. J. EDMUNDS a1c1, R. G. PEBODY a1, H. AGGERBACK a2, S. BARON a3, G. BERBERS a4, M. A. E. CONYN-VAN SPAENDONCK a4, H. O. HALLANDER a5, R. OLANDER a6, P. A. C. MAPLE a7, H. E. DE MELKER a4, P. OLIN a5, F. FIEVRET-GROYNE a8, C. ROTA a9, S. SALMASO a9, A. TISCHER a10, C. VON-HUNOLSTEIN a9 and E. MILLER a1 1
a1 PHLS Communicable Disease Surveillance Centre, 61 Colindale Avenue, London, NW9 5EQ, UK
a2 Statens Serum Institut, Copenhagen, Denmark
a3 Reseau National de Sante Publique, Paris, France
a4 National Institute of Public Health and the Environment, Bilthoven, The Netherlands
a5 Swedish Institute of Infectious Disease Control, Stockholm, Sweden
a6 National Public Health Institute, Helsinki, Finland
a7 Central Public Health Laboratory, London, UK
a8 Pasteur-Mérieux Connaught, Paris, France
a9 Istituto Superiore di Sanita, Rome, Italy
a10 Robert Koch-Institut, Berlin, Germany

Abstract

Seven countries in Western Europe collected large, representative serum banks across the entire age range and tested them for diphtheria anti-toxin (sample size ranged from 2991 to 7715). Although a variety of assays were used, the results were all standardized to those of a reference laboratory and expressed in international units. The standardization process, and the availability of similar, large data sets allowed comparative analyses to be performed in which a high degree of confidence could be ascribed to observed epidemiological differences. The results showed that there were large differences in the proportion of adults with insufficient levels of protection amongst different countries. For instance, roughly 35% of 50- to 60-year-olds were found to be seronegative (titre [less-than-or-eq, slant] 0·01 IU/ml) in Finland compared with 70–75% in the United Kingdom. Furthermore, the proportion of seronegative adults would be expected to increase in some countries, notably Italy and the western part of Germany. In those countries with vaccination of military recruits there was a marked sex-related difference in the proportion of seropositive individuals. All countries have high levels of infant vaccine coverage (> 90%) but the accelerated schedule in the United Kingdom appears to result in lower anti-toxin titres than elsewhere. In Sweden, booster doses are not offered until 10 years of age which results in large numbers of children with inadequate levels of protection. Although the United Kingdom and Sweden both have higher proportions of seronegative children than elsewhere the likelihood of a resurgence of diphtheria in these countries seems remote.

(Accepted February 15 2000)


Correspondence:
c1 Author for correspondence.


Footnotes

1 On behalf of the ESEN Project



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