Campylobacter seroconversion rates in selected countries in the European Union

Abstract

As a major foodborne pathogen, Campylobacter is frequently isolated from food sources of animal origin. In contrast, human Campylobacter illness is relatively rare, but has a considerable health burden due to acute enteric illness as well as severe sequelae. To study silent transmission, serum antibodies can be used as biomarkers to estimate seroconversion rates, as a proxy for infection pressure. This novel approach to serology shows that infections are much more common than disease, possibly because most infections remain asymptomatic. This study used antibody titres measured in serum samples collected from healthy subjects selected randomly in the general population from several countries in the European Union (EU). Estimates of seroconversion rates to Campylobacter were calculated for seven countries: Romania, Poland, Italy, France, Finland, Denmark and The Netherlands. Results indicate high infection pressures in all these countries, slightly increasing in Eastern EU countries. Of these countries, the differences in rates of notified illnesses are much greater, with low numbers in France and Poland, possibly indicating lower probability of detection due to differences in the notification systems, but in the latter case it cannot be excluded that more frequent exposure confers better protection due to acquired immunity.

Fig. 1.

[colour online]. Longitudinal model output: serum antibody responses of (a) IgA, (b) IgM and (c) IgG to Campylobacter infection. Observed data (circles) and model responses, for each individual person in the study.

Fig. 2.

Seroconversion rates based on combined antibodies (joint IgG, IgM, IgA).

Fig. 3.

Comparing seroconversion rates with incidences estimated in returning Swedish travellers (1997–2003) for Finland (FI), Denmark (DK), The Netherlands (NL 1996, 1998, 2006), Italy (IT), France (FR), Poland (PL) and Romania (RM) using data from Ekdahl & Giesecke [27]. Ellipsoids indicate 95% confidence intervals for either estimate.