Serological cross-sectional studies on salmonella incidence in eight European countries: no correlation with incidence of reported cases

Abstract

BackgroundPublished incidence rates of human salmonella infections are mostly based on numbers of stool culture-confirmed cases reported to public health surveillance. These cases constitute only a small fraction of all cases occurring in the community. The extent of underascertainment is influenced by health care seeking behaviour and sensitivity of surveillance systems, so that reported incidence rates from different countries are not comparable. We performed serological cross-sectional studies to compare infection risks in eight European countries independent of underascertainment.MethodsA total of 6,393 sera from adults in Denmark, Finland, France, Italy, Poland, Romania, Sweden, and The Netherlands were analysed, mostly from existing serum banks collected in the years 2003 to 2008. Immunoglobulin A (IgA), IgM, and IgG against salmonella lipopolysaccharides were measured by in-house mixed ELISA. We converted antibody concentrations to estimates of infection incidence (‘sero-incidence’) using a Bayesian backcalculation model, based on previously studied antibody decay profiles in persons with culture-confirmed salmonella infections. We compared sero-incidence with incidence of cases reported through routine public health surveillance and with published incidence estimates derived from infection risks in Swedish travellers to those countries.ResultsSero-incidence of salmonella infections ranged from 56 (95% credible interval 8–151) infections per 1,000 person-years in Finland to 547 (343–813) in Poland. Depending on country, sero-incidence was approximately 100 to 2,000 times higher than incidence of culture-confirmed cases reported through routine surveillance, with a trend for an inverse correlation. Sero-incidence was significantly correlated with incidence estimated from infection risks in Swedish travellers.ConclusionsSero-incidence estimation is a new method to estimate and compare the incidence of salmonella infections in human populations independent of surveillance artefacts. Our results confirm that comparison of reported incidence between countries can be grossly misleading, even within the European Union. Because sero-incidence includes asymptomatic infections, it is not a direct measure of burden of illness. But, pending further validation of this novel method, it may be a promising and cost-effective way to assess infection risks and to evaluate the effectiveness of salmonella control programmes across countries or over time.

Serological survey of anti-Salmonella antibodies in coatis (Nasua narica) and raccoons (Procyon lotor) in southeast Mexico

“…Another possible source of infection could be the polluted water from the surrounding lagoon because animals have free access to this water, and a recent report describes the presence of another zoonotic bacterium, Leptospira interrogans, in resident Antillean manatees (Trichechus manatus) from the same landlocked lagoon (Aragón-Martínez et al 2014). Finally, the high pattern of Salmonella seroprevalence observed indicates an elevated proportion of subclinical infections in coatis and raccoons, a tendency previously demonstrated in human populations (Falkenhorst et al 2012). Thus, the presence of Salmonella in semi-urban wildlife could represent a serious threat to both humans and wildlife, and both sides of this issue need to be addressed: 1) Procyonids from this tourist park might represent a potential source of human infection because animals can act as asymptomatic carriers.…”

“…This estimation method has also been successfully tested in human populations to appraise and compare the prevalence and incidence of Salmonella (Falkenhorst et al 2012). However, it is important to corroborate this finding with other techniques such as molecular or isolation analyses, to verify the accuracy of the serodiagnosis for each species.…”

A Systematic and Critical Review of Model-Based Economic Evaluations of Pharmacotherapeutics in Patients with Bipolar Disorder

“…Therefore countryspecific MFs should be used if possible [14,64,65]. The MFs estimated in this paper are the only ones available based on Swedish data, and these are therefore considered to be the most accurate estimates available.…”

Campylobacter, Salmonella, and Yersinia antibodies and pregnancy outcome in Danish women with occupational exposure to animals

“…20 The Salmonella assay detects human antibodies against S. enterica serovar Enteritidis and S. enterica serovar Typhimurium by a mix of serovar Enteritidis lipopolysaccharide (LPS) and serovar Typhimurium LPS. [21][22][23] The Yersinia assay detects human antibodies against Y. enterocolitica serogroup O:3. The ELISA uses LPS from Y. enterocolitica serogroup O:3 as the detecting antigen.…”