Human Campylobacteriosis in Luxembourg, 2010–2013: A Case-Control Study Combined with Multilocus Sequence Typing for Source Attribution and Risk Factor Analysis

Abstract

Campylobacteriosis has increased markedly in Luxembourg during recent years. We sought to determine which Campylobacter genotypes infect humans, where they may originate from, and how they may infect humans. Multilocus sequence typing was performed on 1153 Campylobacter jejuni and 136 C. coli human strains to be attributed to three putative animal reservoirs (poultry, ruminants, pigs) and to environmental water using the asymmetric island model. A nationwide case-control study (2010–2013) for domestic campylobacteriosis was also conducted, including 367 C. jejuni and 48 C. coli cases, and 624 controls. Risk factors were investigated by Campylobacter species, and for strains attributed to different sources using a combined case-control and source attribution analysis. 282 sequence types (STs) were identified: ST-21, ST-48, ST-572, ST-50 and ST-257 were prevailing. Most cases were attributed to poultry (61.2%) and ruminants (33.3%). Consuming chicken outside the home was the dominant risk factor for both Campylobacter species. Newly identified risk factors included contact with garden soil for either species, and consuming beef specifically for C. coli. Poultry-associated campylobacteriosis was linked to poultry consumption in wintertime, and ruminant-associated campylobacteriosis to tap-water provider type. Besides confirming chicken as campylobacteriosis primary source, additional evidence was found for other reservoirs and transmission routes.

Attribution of human infections with Shiga toxin‐producing Escherichia coli (STEC) to livestock sources and identification of source‐specific risk factors, The Netherlands (2010–2014)

“…The aim of this study was to quantify the relative contributions of cattle, small ruminants, pigs and poultry to the human disease burden of STEC infection and to determine risk factors for infection with STEC strains originating from these livestock sources in the Netherlands. Previous studies with this same aim focussed on Campylobacter (Mossong et al., ; Mughini‐Gras et al., ) and Salmonella (Mughini‐Gras, Enserink, et al., ). We then used quantitative risk modelling to attribute stochastically human STEC infections to sources based on O‐serotyping data.…”

“…Given the source specificity of certain subtypes of the pathogen in question and assuming a unidirectional transmission pathway from sources to humans (with humans representing the endpoint), the relative contribution of each source to human cases can be inferred probabilistically by comparing the pathogen subtype distributions in humans and sources. While source attribution studies for pathogens like Salmonella , Campylobacter and Listeria based on the microbial subtyping approach have been performed in many countries worldwide (Barco, Barrucci, Olsen, & Ricci, ; Boysen et al., ; David et al., ; Guo et al., ; de Knegt, Pires, & Hald, ; Levesque et al., ; Little, Pires, Gillespie, Grant, & Nichols, ; Mossong et al., ; Mughini‐Gras & van Pelt, ; Mughini‐Gras et al., ; Mughini‐Gras, Barrucci, et al. ; Mughini‐Gras, Enserink, et al., ; Mughini‐Gras, Smid, et al., ; Mullner, Jones, et al., ; Mullner, Spencer, et al., ; Pires & Hald, ; Pires et al., ; Sheppard et al., ; Strachan et al., ; Wahlstrom, Andersson, Plym‐Forshell, & Pires, ; Wilson et al., ), no comparable study on STEC has been performed so far.…”

“…; Mughini‐Gras, Enserink, et al., ; Mughini‐Gras, Smid, et al., ; Mullner, Jones, et al., ; Mullner, Spencer, et al., ; Pires & Hald, ; Pires et al., ; Sheppard et al., ; Strachan et al., ; Wahlstrom, Andersson, Plym‐Forshell, & Pires, ; Wilson et al., ), no comparable study on STEC has been performed so far. Moreover, to understand how STEC strains originating from specific animal sources infect humans (i.e., to uncover the underlying transmission routes), combined (source‐assigned) case–control and source attribution analyses have been performed for Salmonella (Mughini‐Gras, Enserink, et al., ) and Campylobacter (Mossong et al., ; Mughini‐Gras et al., ) to bridge the gap between attributing human cases at the start of the transmission chain (i.e., reservoir level) and at the point of exposure (i.e., risk factors) to identify source‐specific risk factors for human infection.…”

Genome-Wide Identification of Host-Segregating Epidemiological Markers for Source Attribution in Campylobacter jejuni

“…Self-attribution tests focused on chicken isolates (n ϭ 352) and ruminant isolates (n ϭ 59) as the source of the majority of isolates in this study and major reservoirs of human infection by C. jejuni. Furthermore, generalist ST-21 and ST-45 clonal complexes are common in these hosts but have been difficult to attribute to source using seven-locus MLST (23,26,29,34,49). Host attribution was performed using STRUCTURE software, a Bayesian model-based clustering method designed to infer population structure and attribute individuals to populations using multilocus genotype data (74).…”

The consequences of Campylobacter infection

“…The majority of Campylobacter cases are unrelated to outbreaks. Newly identified risk factors for sporadic in recently published case-control studies include contact with garden soil for C. jejuni and C. coli, and consuming beef (C. coli only) [40], and eating cantaloupe and queso fresco (Mexican cheese) [41]. However, consumption of contaminated poultry continues to feature prominently in the epidemiology of sporadic cases [42,43].…”