Risk Factors for Sporadic Domestically Acquired Campylobacter Infections in Norway 2010-2011: A National Prospective Case-Control Study

Assessing concordance between Campylobacter prevalence in broilers and human cases before and during the COVID-19 pandemic in Lower Saxony, Germany, considering fresh chicken meat consumption patterns

As the most common foodborne disease, number of campylobacteriosis decreased in Germany with the beginning of the COVID-19 pandemic in 2020. As the consumption of fresh chicken meat is a major risk factor for human infection, this study investigated the relationship between Campylobacter contamination levels on chicken carcasses and human cases in Lower Saxony, Germany and observed fresh chicken meat consumption patterns between 2018 and 2021 including the time of the COVID-19 pandemic. Campylobacter levels in broilers and human cases were classified based on the median and descriptively analysed per week using contingency tables. Before the COVID-19 pandemic (2018 and 2019), high Campylobacter contamination levels on neck samples and many human cases were more present, whereas with the beginning of the COVID-19 pandemic (2020 and 2021), low contamination levels on chicken carcasses and few human cases were more present. Lowest concordance between both parameters was shown in 2018 (Cohen's cappa coefficient: 0.37) and 2020 (0.38). The highest concordance was examined in 2021 (0.69). The private consumption of fresh chicken meat in Lower Saxony increased significantly with the beginning of the COVID-19 pandemic in 2020 by 63.9 tonnes compared to 2019 to an average of 453.5 tonnes per week. Public health measures and a reduced number of medical treatments have undoubtedly had an impact on less reported human cases during the COVID-19 pandemic. However, number of human cases remained at a low level in Germany in 2023 while chicken meat consumption increased. Thus, further risk assessments regarding the risk of campyloabcteriosis due to chicken meat consumption should include the country of origin, as the level of contamination of chicken carcasses varies between European countries.

Campylobacter in aquatic and terrestrial mammals is driven by life traits: A systematic review and meta-analysis

Introduction

Campylobacter spp. infections are responsible for significant diarrheal disease burden across the globe, with prevalence thought to be increasing. Although wild avian species have been studied as reservoirs of Campylobacter spp., our understanding of the role of wild mammalian species in disease transmission and persistence is limited. Host factors influencing infection dynamics in wild mammals have been neglected, particularly life traits, and the role of these factors in zoonotic spillover risk is largely unknown.

Methods

Here, we conducted a systematic literature review, identifying mammalian species that had been tested for Campylobacter spp. infections (molecular and culture based). We used logistic regression to evaluate the relationship between the detection of Campylobacter spp. in feces and host life traits (urban association, trophic level, and sociality).

Results

Our analysis suggest that C. jejuni transmission is associated with urban living and trophic level. The probability of carriage was highest in urban-associated species (p = 0.02793) and the most informative model included trophic level. In contrast, C. coli carriage appears to be strongly influenced by sociality (p = 0.0113) with trophic level still being important. Detection of Campylobacter organisms at the genus level, however, was only associated with trophic level (p = 0.0156), highlighting the importance of this trait in exposure dynamics across host and Campylobacter pathogen systems.

Discussion

While many challenges remain in the detection and characterization of Camploybacter spp., these results suggest that host life traits may have important influence on pathogen exposure and transmission dynamics, providing a useful starting point for more directed surveillance approaches.

A One Health real-time surveillance system for nowcasting Campylobacter gastrointestinal illness outbreaks, Norway, week 30 2010 to week 11 2022

BackgroundCampylobacter is a leading cause of food and waterborne illness. Monitoring and modelling Campylobacter at chicken broiler farms, combined with weather pattern surveillance, can aid nowcasting of human gastrointestinal (GI) illness outbreaks. Near real-time sharing of data and model results with health authorities can help increase potential outbreak responsiveness.AimsTo leverage data on weather and Campylobacter on broiler farms to build a risk model for possible human Campylobacter outbreaks and to communicate risk assessments with health authorities.MethodsWe developed a spatio-temporal random effects model for weekly GI illness consultations in Norwegian municipalities with Campylobacter monitoring and weather data from week 30 2010 to 11 2022 to give 1-week nowcasts of GI illness outbreaks. The approach combined a municipality random effects baseline model for seasonally-adjusted GI illness with a second model for peak deviations from that baseline. Model results are communicated to national and local stakeholders through an interactive website: Sykdomspulsen One Health.ResultsLagged temperature and precipitation covariates, as well as 2-week-lagged positive Campylobacter sampling in broilers, were associated with higher levels of GI consultations. Significant inter-municipality variability in outbreak nowcasts were observed.ConclusionsCampylobacter surveillance in broilers can be useful in GI illness outbreak nowcasting. Surveillance of Campylobacter along potential pathways from the environment to illness such as via water system monitoring may improve nowcasting. A One Health system that communicates near real-time surveillance data and nowcast changes in risk to health professionals facilitates the prevention of Campylobacter outbreaks and reduces impact on human health.

Metaphenotypes associated with recurrent genomic lineages of Campylobacter jejuni responsible for human infections in Luxembourg

Campylobacter jejuni is a leading cause of foodborne illnesses worldwide. Although considered fragile, this microaerophilic bacterium is able to survive in various challenging environments, which subsequently constitutes multiple sources of transmission for human infection. To test the assumption of acquiring specific features for adaptation and survival, we established a workflow of phenotypic tests related to the survival and the persistence of recurrent and sporadic strains. A representative collection of 83 strains isolated over 13 years from human, mammal, poultry, and environmental sources in Luxembourg, representing different spreading patterns (endemic, epidemic, and sporadic), was screened for survival to oxidative stresses, for acclimating to aerobic conditions (AC), and for persistence on abiotic surfaces. Using the cgMLST Oxford typing scheme for WGS data, the collection was classified into genomic lineages corresponding to host-generalist strains (lineages A and D, CC ST-21), host-specific strains (lineage B, CC ST-257 and lineage C, CC ST-464) and sporadic strains. We established that when a strain survives concentrations beyond 0.25 mM superoxide stress, it is six times more likely to survive hyperoxide stress and that a highly adherent strain is 14 times more likely to develop a biofilm. Surprisingly, more than half of the strains could acclimate to AC but this capacity does not explain the difference between recurrent genomic lineages and sporadic strains and the survival to oxidative stresses, while recurrent strains have a significantly higher adhesion/biofilm formation capacity than sporadic ones. From this work, the genomic lineages with more stable genomes could be characterized by a specific combination of phenotypes, called metaphenotypes. From the functional genomic analyses, the presence of a potentially functional T6SS in the strains of lineage D might explain the propensity of these strains to be strong biofilm producers. Our findings support the hypothesis that phenotypical abilities contribute to the spatio-temporal adaptation and survival of stable genomic lineages. It suggests a selection of better-adapted and persistent strains in challenging stress environments, which could explain the prevalence of these lineages in human infections.

Nearest-Neighbors Matching for Case-Control Study Analyses: Better Risk Factor Identification From a Study of Sporadic Campylobacteriosis in the United States

BACKGROUND

Case-control studies are commonly used to explore factors associated with enteric bacterial diseases. Control of confounding is challenging due to a large number of exposures of interest and the low frequencies of many of them.

METHODS

We evaluated nearest-neighbors matching in a case-control study (originally 1:1 matched, published in 2004) of sporadic Campylobacter infections that included information on 433 exposures in 2632 subjects during 1998-1999. We performed multiple imputations of missing data (m = 100) and calculated Gower distances between cases and controls using all possible confounders for each exposure in each dataset. We matched each case with ≤20 controls within a data-determined distance. We calculated odds ratios and population attributable fractions (PAFs).

RESULTS

Examination of pairwise correlation between exposures found very strong associations for 1046 pairs of exposures. More than 100 exposures were associated with campylobacteriosis, including nearly all risk factors identified using the previously published approach that included only 16 exposures and some less studied, rare exposures such as consumption of chicken liver and raw clams. Consumption of chicken and nonpoultry meat had the highest PAFs (62% and 59%, respectively).

CONCLUSIONS

Nearest-neighbors matching appear to provide an improved ability to examine rare exposures and better control for numerous highly associated confounders.

Risk factors for campylobacteriosis in Australia: outcomes of a 2018-2019 case-control study

BACKGROUND

We aimed to identify risk factors for sporadic campylobacteriosis in Australia, and to compare these for Campylobacter jejuni and Campylobacter coli infections.

METHODS

In a multi-jurisdictional case-control study, we recruited culture-confirmed cases of campylobacteriosis reported to state and territory health departments from February 2018 through October 2019. We recruited controls from notified influenza cases in the previous 12 months that were frequency matched to cases by age group, sex, and location. Campylobacter isolates were confirmed to species level by public health laboratories using molecular methods. We conducted backward stepwise multivariable logistic regression to identify significant risk factors.

RESULTS

We recruited 571 cases of campylobacteriosis (422 C. jejuni and 84 C. coli) and 586 controls. Important risk factors for campylobacteriosis included eating undercooked chicken (adjusted odds ratio [aOR] 70, 95% CI 13-1296) or cooked chicken (aOR 1.7, 95% CI 1.1-2.8), owning a pet dog aged < 6 months (aOR 6.4, 95% CI 3.4-12), and the regular use of proton-pump inhibitors in the 4 weeks prior to illness (aOR 2.8, 95% CI 1.9-4.3). Risk factors remained similar when analysed specifically for C. jejuni infection. Unique risks for C. coli infection included eating chicken pâté (aOR 6.1, 95% CI 1.5-25) and delicatessen meats (aOR 1.8, 95% CI 1.0-3.3). Eating any chicken carried a high population attributable fraction for campylobacteriosis of 42% (95% CI 13-68), while the attributable fraction for proton-pump inhibitors was 13% (95% CI 8.3-18) and owning a pet dog aged < 6 months was 9.6% (95% CI 6.5-13). The population attributable fractions for these variables were similar when analysed by campylobacter species. Eating delicatessen meats was attributed to 31% (95% CI 0.0-54) of cases for C. coli and eating chicken pâté was attributed to 6.0% (95% CI 0.0-11).

CONCLUSIONS

The main risk factor for campylobacteriosis in Australia is consumption of chicken meat. However, contact with young pet dogs may also be an important source of infection. Proton-pump inhibitors are likely to increase vulnerability to infection.

Antimicrobial Resistance Development Pathways in Surface Waters and Public Health Implications

Human health is threatened by antibiotic-resistant bacteria and their related infections, which cause thousands of human deaths every year worldwide. Surface waters are vulnerable to human activities and natural processes that facilitate the emergence and spread of antibiotic-resistant bacteria in the environment. This study evaluated the pathways and drivers of antimicrobial resistance (AR) in surface waters. We analyzed antibiotic resistance healthcare-associated infection (HAI) data reported to the CDC's National Healthcare Safety Network to determine the number of antimicrobial-resistant pathogens and their isolates detected in healthcare facilities. Ten pathogens and their isolates associated with HAIs tested resistant to the selected antibiotics, indicating the role of healthcare facilities in antimicrobial resistance in the environment. The analyzed data and literature research revealed that healthcare facilities, wastewater, agricultural settings, food, and wildlife populations serve as the major vehicles for AR in surface waters. Antibiotic residues, heavy metals, natural processes, and climate change were identified as the drivers of antimicrobial resistance in the aquatic environment. Food and animal handlers have a higher risk of exposure to resistant pathogens through ingestion and direct contact compared with the general population. The AR threat to public health may grow as pathogens in aquatic systems adjust to antibiotic residues, contaminants, and climate change effects. The unnecessary use of antibiotics increases the risk of AR, and the public should be encouraged to practice antibiotic stewardship to decrease the risk.

Investigating the Campylobacter enteritis winter peak in Germany, 2018/2019

Surveillance of notified Campylobacter enteritis in Germany revealed a recurrent annual increase of cases with disease onset several days after the Christmas and New Year holidays ("winter peak"). We suspected that handling and consumption of chicken meat during fondue and raclette grill meals on the holidays were associated with winter peak Campylobacter infections. The hypothesis was investigated in a case-control study with a case-case design where notified Campylobacter enteritis cases served as case-patients as well as control-patients, depending on their date of disease onset (case-patients: 25/12/2018 to 08/01/2019; control-patients: any other date between 30/11/2018 and 28/02/2019). The study was conducted as an online survey from 21/01/2019 to 18/03/2019. Adjusted odds ratios (aOR) were determined in single-variable logistic regression analyses adjusted for age group and sex. We analysed 182 data sets from case-patients and 260 from control-patients and found associations of Campylobacter infections after the holidays with meat fondue (aOR 2.2; 95% confidence interval (CI) 1.2-3.8) and raclette grill meals with meat (aOR 1.5; 95% CI 1.0-2.4) consumed on the holidays. The associations were stronger when chicken meat was served at these meals (fondue with chicken meat: aOR 2.7; 95% CI 1.4-5.5; raclette grill meal with chicken meat: aOR 2.3; 95% CI 1.3-4.1). The results confirmed our initial hypothesis. To prevent Campylobacter winter peak cases in the future, consumers should be made more aware of the risks of a Campylobacter infection when handling raw meat, in particular chicken, during fondue or raclette grill meals on the holidays.

Heavy weather events, water quality and gastroenteritis in Norway

Climate change will lead to more extreme weather events in Europe. In Norway, little is known about how this will affect drinking water quality and population's health due to waterborne diseases. The aim of our work was to generate new knowledge on the effect of extreme weather conditions and climate change on drinking water and waterborne disease. In this respect we studied the relationship between temperature, precipitation and runoff events, raw and treated water quality, and gastroenteritis consultations in Norway in 2006–2014 to anticipate the risk with changing climate conditions. The main findings are positive associations between extreme weather events and raw water quality, but only few with treated drinking water. Increase in maximum temperature was associated with an increase in risk of disease among all ages and 15–64 years olds for the whole year. Heavy rain and high runoff were associated with a decrease in risk of gastroenteritis for different age groups and time periods throughout the year. No evidence was found that increase in precipitation and runoff trigger increased gastroenteritis outbreaks. Large waterworks in Norway currently seem to manage extreme weather events in preventing waterborne disease. However, with more extreme weather in the future, this may change. Therefore, modelling future climate scenarios is necessary to assess the need for improved water treatment capacity in a future climate.

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Positive associations between extreme weather events and raw water quality.

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Increase in maximum temperature was associated with an increase in risk of disease.

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Heavy rain and high runoff were associated with a decrease in risk of gastroenteritis.

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Larger water works in Norway seem to cope with the extreme weather events in the current climate.

Sexual Contact as Risk Factor for Campylobacter Infection, Denmark

Campylobacteriosis is a disease of worldwide importance, but aspects of its transmission dynamics, particularly risk factors, are still poorly understood. We used data from a matched case-control study of 4,269 men who have sex with men (MSM) and 26,215 controls, combined with national surveillance data on Campylobacter spp., Salmonella spp., and Shigella spp., to calculate matched odds ratios (mORs) for infection among MSM and controls. MSM had higher odds of Campylobacter (mOR 14, 95% CI 10–21) and Shigella (mOR 74, 95% CI 27–203) infections, but not Salmonella (mOR 0.2, 95% CI 0–13), and were less likely than controls to have acquired Campylobacter infection abroad (χ² = 21; p<0.001). Our results confirm that sexual contact is a risk factor for campylobacteriosis and also suggest explanations for unique features of Campylobacter epidemiology. These findings provide a baseline for updating infection risk guidelines to the general population.

Clinical features of gastroenteritis during a large waterborne Campylobacter outbreak in Askøy, Norway

Purpose

Outbreaks of Campylobacter infection are common, but studies exploring the clinical features of acute illness in the outbreak setting are scarce in existing literature. The main purpose of the present study was to investigate the clinical features of self-reported acute illness in gastroenteritis cases during a large waterborne Campylobacter outbreak in Askøy municipality, Norway, in 2019.

Methods

A web-based self-administered questionnaire, and invitation to participate was sent by the municipality of Askøy as text message to mobile phones using the municipality’s warning system to the inhabitants during the ongoing outbreak.

Results

Out of 3624 participants, 749 (20.7%) were defined as cases, of which 177 (23.6%) reported severe gastroenteritis. The most common symptoms were loose stools (90.7%), abdominal pain (89.3%) and diarrhea (88.9%), whereas 63.8% reported fever, 50.2% joint pain and 14.2% bloody stools. Tiredness, a symptom non-specific to gastroenteritis, was the overall most common symptom (91.2%).

Conclusion

About one in four of the cases reported symptoms consistent with severe gastroenteritis. We found more joint pain and less bloody stools than reported in published studies of laboratory confirmed campylobacteriosis cases. Tiredness was common in the current study, although rarely described in previous literature of acute illness in the outbreak setting.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-021-01652-3.

Cross-contamination of lettuce with Campylobacter spp. via cooking salt during handling raw poultry

Campylobacter spp. are the most common bacterial pathogens associated with human gastroenteritis in industrialized countries. Contaminated chicken is the food vehicle associated with the majority of reported cases of campylobacteriosis, either by the consumption of undercooked meat or via cross- contamination of ready-to-eat (RTE) foods during the handling of contaminated raw chicken parts and carcasses. Our results indicate that cooking salt (used for seasoning) is a potential vehicle for Campylobacter spp. cross-contamination from raw chicken to lettuce, through unwashed hands after handling contaminated chicken. Cross-contamination events were observed even when the chicken skin was contaminated with low levels of Campylobacter spp. (ca. 1.48 Log CFU/g). The pathogen was recovered from seasoned lettuce samples when raw chicken was contaminated with levels ≥ 2.34 Log CFU/g. We also demonstrated that, once introduced into cooking salt, Campylobacter spp. are able to survive in a culturable state up to 4 hours. After six hours, although not detected following an enrichment period in culture medium, intact cells were observed by transmission electron microscopy. These findings reveal a "novel" indirect cross-contamination route of Campylobacter in domestic settings, and a putative contamination source to RTE foods that are seasoned with salt, that might occur if basic food hygiene practices are not adopted by consumers when preparing and cooking poultry dishes.

Human Campylobacteriosis Cases Traceable to Chicken Meat-Evidence for Disseminated Outbreaks in Finland

Campylobacter jejuni (C. jejuni) is the most common cause of human bacterial gastroenteritis in the world. Food-borne campylobacteriosis is thought to be commonly caused by the handling and consumption of undercooked chicken meat, but the epidemiology of this disease is complex and remains poorly characterized, especially in the Nordic countries. Here, we used state-of-the-art methods in genetic epidemiology combined with patient background and temporal association data to trace domestically acquired human C. jejuni infections (n = 50) to chicken meat, in a midsize Nordic town in Finland during a seasonal peak. Although 59.2% of the human isolates shared a sequence type (ST) with a chicken batch slaughtered prior to the onset of disease, further analysis at the whole-genome level (core genome and whole-genome multilocus sequence typing, cgMLST and wgMLST, respectively) traced a mere nine cases (18.4%) to fresh chicken meat. Human isolates also shared genotypes with isolates collected from chicken batches slaughtered after the onset of the human disease, highlighting the role of alternative transmission pathways from chickens to humans besides the food chain, or a shared third source. The high resolution offered by wgMLST, combined with simple metadata, offers a more accurate way to trace sporadic cases to possible sources and reveal disseminated outbreak clustering in time, confirming the importance of complementing epidemiological investigations with molecular epidemiological data.

Campylobacter infections expected to increase due to climate change in Northern Europe

Global climate change is predicted to alter precipitation and temperature patterns across the world, affecting a range of infectious diseases and particularly foodborne infections such as Campylobacter. In this study, we used national surveillance data to analyse the relationship between climate and campylobacteriosis in Denmark, Finland, Norway and Sweden and estimate the impact of climate changes on future disease patterns. We show that Campylobacter incidences are linked to increases in temperature and especially precipitation in the week before illness, suggesting a non-food transmission route. These four countries may experience a doubling of Campylobacter cases by the end of the 2080s, corresponding to around 6,000 excess cases per year caused only by climate changes. Considering the strong worldwide burden of campylobacteriosis, it is important to assess local and regional impacts of climate change in order to initiate timely public health management and adaptation strategies.

Recovery of thermophilic Campylobacter by three sampling methods from river sites in Northeast Georgia, USA, and their antimicrobial resistance genes

Sixteen sites in the watershed of the South Fork of the Broad River (SFBR) in Northeastern Georgia, USA, were sampled in two seasons to detect Campylobacter. Sites were classified as mostly influenced by forest, pasture, wastewater pollution control plants (WPC) or mixed use. Sampling was repeated in the late spring and late fall for 2 years for a total of 126 samples. Free-catch water and sediment grab samples were taken at each site; Moore's swabs were placed for up to 3 days at most sites. A total of 56 isolates of thermophilic Campylobacter were recovered. Thirteen samplings were positive by two or three methods, and 26 samplings were positive by only one method; once by Moore's swab only and 25 times by free-catch water only. Campylobacter was detected at 58% of cattle pasture sites, 30% of forested sites and 81% of WPC sites. Twenty-one of the isolates carried antimicrobial resistance genes, mostly blaOXA-61. Free-catch water samples were more efficient than Moore's swabs or sediment samples for recovery of Campylobacter, which was more likely to be detected in streams near cattle pastures and human communities than in forested land. SIGNIFICANCE AND IMPACT OF THE STUDY: The role of environmental water in transmitting Campylobacter was investigated, and methods for recovery of the organism were compared. The sequence types of recovered Campylobacter correlated with adjacent land use without regard to the method used to isolate the organisms. Sequence types and antimicrobial resistance genes associated with cattle were most prevalent near pastures. Even though types were recurrent at a given site, types appeared to be lost or replaced as the water flowed downstream.

Pathogen-Specific Impacts of the 2011-2012 La Niña-Associated Floods on Enteric Infections in the MAL-ED Peru Cohort: A Comparative Interrupted Time Series Analysis

Extreme floods pose multiple direct and indirect health risks. These risks include contamination of water, food, and the environment, often causing outbreaks of diarrheal disease. Evidence regarding the effects of flooding on individual diarrhea-causing pathogens is limited, but is urgently needed in order to plan and implement interventions and prioritize resources before climate-related disasters strike. This study applied a causal inference approach to data from a multisite study that deployed broadly inclusive diagnostics for numerous high-burden common enteropathogens. Relative risks (RRs) of infection with each pathogen during a flooding disaster that occurred at one of the sites-Loreto, Peru-were calculated from generalized linear models using a comparative interrupted time series framework with the other sites as a comparison group and adjusting for background seasonality. During the early period of the flood, increased risk of heat-stable enterotoxigenic E. coli (ST-ETEC) was identified (RR = 1.73 [1.10, 2.71]) along with a decreased risk of enteric adenovirus (RR = 0.36 [0.23, 0.58]). During the later period of the flood, sharp increases in the risk of rotavirus (RR = 5.30 [2.70, 10.40]) and sapovirus (RR = 2.47 [1.79, 3.41]) were observed, in addition to increases in transmission of Shigella spp. (RR = 2.86 [1.81, 4.52]) and Campylobacter spp. (RR = 1.41 (1.01, 1.07). Genotype-specific exploratory analysis reveals that the rise in rotavirus transmission during the flood was likely due to the introduction of a locally atypical, non-vaccine (G2P[4]) strain of the virus. Policy-makers should target interventions towards these pathogens-including vaccines as they become available-in settings where vulnerability to flooding is high as part of disaster preparedness strategies, while investments in radical, transformative, community-wide, and locally-tailored water and sanitation interventions are also needed.

Campylobacteriosis in the Nordic countries from 2000 to 2015: Trends in time and space

Aims: This study aimed to describe the demographic and geographic patterns of campylobacteriosis in Denmark, Finland, Norway and Sweden during 2000-2015. Methods: All Campylobacter infections notified to national authorities in the four countries during the study period were included. Background data for each notification consisted of patient age, sex, geographical location, presumed origin of infection and date of sample taken or date of sample received in the laboratory. These data were analysed in order to investigate annual trends, age group and sex patterns, as well as variations in the geographical and seasonal distribution of infections. Results: During the study period, a total of 164,001 Campylobacter infections, excluding travel-related cases, were registered, representing a mean annual incidence of 42.3 cases/100,000 population (ranging from 28.5 in Norway to 60.4 in Denmark). The incidence increased significantly from 2004 onwards in all countries, apart from Denmark. Males had higher infection rates in general. The highest incidences were observed in 0-4 year olds and those aged 20-29 years, apart from in Finland where there was no peak of infections in children aged 0-4 years. Seasonality of disease was distinct in all four countries, showing peaks of infection between July and August. In Sweden and Norway, incidences of campylobacteriosis were significantly higher in municipalities with high degrees of coastline or inland water. Conclusions: Campylobacter in the Nordic countries mostly follows known patterns with respect to demography and seasonality. Our study demonstrates new insights concerning geographical patterns of disease, highlighting possible future vulnerable population groups and locations.

Climate, human behaviour or environment: individual-based modelling of Campylobacter seasonality and strategies to reduce disease burden

Background

With over 800 million cases globally, campylobacteriosis is a major cause of food borne disease. In temperate climates incidence is highly seasonal but the underlying mechanisms are poorly understood, making human disease control difficult. We hypothesised that observed disease patterns reflect complex interactions between weather, patterns of human risk behaviour, immune status and level of food contamination. Only by understanding these can we find effective interventions.

Methods

We analysed trends in human Campylobacter cases in NE England from 2004 to 2009, investigating the associations between different risk factors and disease using time-series models. We then developed an individual-based (IB) model of risk behaviour, human immunological responses to infection and environmental contamination driven by weather and land use. We parameterised the IB model for NE England and compared outputs to observed numbers of reported cases each month in the population in 2004–2009. Finally, we used it to investigate different community level disease reduction strategies.

Results

Risk behaviours like countryside visits (t = 3.665, P < 0.001 and t = − 2.187, P = 0.029 for temperature and rainfall respectively), and consumption of barbecued food were strongly associated with weather, (t = 3.219, P = 0.002 and t = 2.015, P = 0.045 for weekly average temperature and average maximum temperature respectively) and also rain (t = 2.254, P = 0.02527). This suggests that the effect of weather was indirect, acting through changes in risk behaviour. The seasonal pattern of cases predicted by the IB model was significantly related to observed patterns (r = 0.72, P < 0.001) indicating that simulating risk behaviour could produce the observed seasonal patterns of cases. A vaccination strategy providing short-term immunity was more effective than educational interventions to modify human risk behaviour. Extending immunity to 1 year from 20 days reduced disease burden by an order of magnitude (from 2412–2414 to 203–309 cases per 50,000 person-years).

Conclusions

This is the first interdisciplinary study to integrate environment, risk behaviour, socio-demographics and immunology to model Campylobacter infection, including pathways to mitigation. We conclude that vaccination is likely to be the best route for intervening against campylobacteriosis despite the technical problems associated with understanding both the underlying human immunology and genetic variation in the pathogen, and the likely cost of vaccine development.

Determinants of sporadic Campylobacter infections in Denmark: a nationwide case-control study among children and young adults

BACKGROUND

Each year more than 4,000 cases of campylobacteriosis are reported in Denmark, making it the most common bacterial gastrointestinal infection. Here we describe a case-control study to identify sources of infection with a focus on environmental factors.

METHODS

From January to December 2016, we conducted a prospective case-control study among Danish persons aged 1-30 years. Participants were invited by letter to complete an online questionnaire. Crude and adjusted ORs were calculated and final parsimonious multivariate models developed using logistic regression.

RESULTS

The study recruited 1366 cases and 4,418 controls, of whom 65% and 66%, respectively, completed the questionnaire. A multivariate model for domestically acquired cases showed, among others, increased risk of infection with bathing in fresh water (OR=5.1), contact to beach sand (OR=1.8), owning a pet dog with diarrhea (OR=4.6), and eating minced beef (OR=2.6) or chicken (OR=2.5). The model for children highlighted similar risk factors but also included bathing in a paddling pool (OR=13.6) and eating fresh strawberries (OR=5.3). A separate analysis for persons reporting foreign travel showed increased infection risk when traveling to Asia, Africa, or Turkey and that eating from street kitchens and having contact to water during traveling were also risk factors.

CONCLUSION

Environmental factors and animal contact account for a sizeable proportion of domestic Campylobacter infections in the age group studied. The study also re-confirmed handling/consumption of chicken as an important risk factor while highlighting minced beef as a potential new risk factor. Overall, these results contribute to a better understanding of the transmission dynamics of Campylobacter and will be used to improve national guidelines for prevention of infection.

The role of domestic reservoirs in domestically acquired Salmonella infections in Norway: epidemiology of salmonellosis, 2000-2015, and results of a national prospective case-control study, 2010-2012

In Norway, incidence of sporadic domestically acquired salmonellosis is low, and most frequently due to Salmonalla Typhimurium. We investigated the risk factors for sporadic Salmonella infections in Norway to improve control and prevention measures. Surveillance data for all Salmonella infections from 2000 to 2015 were analysed for seasonality and proportion associated with domestic reservoirs, hedgehogs and wild birds. A prospective case–control study was conducted from 2010 to 2012 by recruiting cases from the Norwegian Surveillance System for Communicable Diseases and controls from the Norwegian Population Registry (389 cases and 1500 controls). Univariable analyses using logistic regression were conducted and a multivariable model was developed using regularised/penalised logistic regression. In univariable analysis, eating snow, dirt, sand or playing in a sandbox (aOR 4.14; CI 2.15–7.97) was associated with salmonellosis. This was also the only exposure significantly associated with illness in the multivariable model. Since 2004, 34.2% (n = 354) of S. Typhimuirum cases had an MLVA profile linked to a domestic reservoir. A seasonal trend with a peak in August for all Salmonella types and in February for S. Typhimurium was observed. Indirect exposure to domestic reservoirs remains a source of salmonellosis in Norway, particularly for children. Information to the public about avoiding environmental exposure should be strengthened and initiatives to combat salmonellosis in the food chain should be reinforced.

Prevalence of Microbiological and Chemical Contaminants in Private Drinking Water Wells in Maryland, USA

Although many U.S. homes rely on private wells, few studies have investigated the quality of these water sources. This cross-sectional study evaluated private well water quality in Maryland, and explored possible environmental sources that could impact water quality. Well water samples (n = 118) were collected in four Maryland counties and were analyzed for microbiological and chemical contaminants. Data from the U.S. Census of Agriculture were used to evaluate associations between the presence of animal feeding operations and well water quality at the zip code level using logistic regression. Overall, 43.2% of tested wells did not meet at least one federal health-based drinking water standard. Total coliforms, fecal coliforms, enterococci, and Escherichia coli were detected in 25.4%, 15.3%, 5.1%, and 3.4% of tested wells, respectively. Approximately 26%, 3.4%, and <1% of wells did not meet standards for pH, nitrate-N, and total dissolved solids, respectively. There were no statistically significant associations between the presence of cattle, dairy, broiler, turkey, or aquaculture operations and the detection of fecal indicator bacteria in tested wells. In conclusion, nearly half of tested wells did not meet federal health-based drinking water standards, and additional research is needed to evaluate factors that impact well water quality. However, homeowner education on well water testing and well maintenance could be important for public health.

Campylobacter, a zoonotic pathogen of global importance: Prevalence and risk factors in the fast-evolving chicken meat system of Nairobi, Kenya

Campylobacteriosis is a leading foodborne zoonosis worldwide, and is frequently associated with handling and consumption of poultry meat. Various studies indicate that Campylobacter causes a substantial human disease burden in low to middle-income countries, but data regarding the organism's epidemiology in countries like Kenya are scarce. In sub-Saharan Africa, 3.8 million deaths of children under-5 years of age are reported annually. Of those, 25% are caused by diarrheal diseases, and Campylobacter is one of the most frequently isolated bacteria from diarrheic children. With the growth of urban conglomerates, such as Kenya's capital, Nairobi, changes in diets, food production systems, and retailing dynamics, it is likely that exposure and susceptibility to this pathogen will change. Therefore, the importance of Campylobacter disease burden in Kenya may increase further. The objectives of this study were: 1) to determine the prevalence of Campylobacter spp. in Nairobi's small-scale chicken farms and meat retailers, and 2) to identify potential risk factors associated with its presence in those sites. The prevalence data provides the first detailed baseline for this pathogen in the urban Kenyan context. The risk factors provide context-specific insights for disease managers. A cross-sectional study of broiler, indigenous chicken farms, and chicken meat retailers, was conducted in a peri-urban, low to middle-income area (Dagoretti), and a very-low income informal settlement (Kibera) of Nairobi. Chicken faeces were collected using one pair of boot socks per farm, and 3 raw chicken meat samples were purchased per retailer. Samples were cultured for viable Campylobacter spp. using mCCDA, followed by blood agar plates in aerobic/microaerobic conditions for prevalence calculations. A questionnaire-based survey on sanitary, sourcing and selling practices was conducted at each site for risk factor identification using logistic regression analyses. A total of 171 farm premises and 53 retailers were sampled and interviewed. The prevalence results for Campylobacter spp. were between 33 to 44% for broiler and indigenous chicken farms, 60% and 64% for retailers, in Dagoretti and Kibera, respectively. Univariable logistic regression showed an association between Campylobacter spp. presence and the easiness of cleaning the display material used by the retailer. Restricting access to the flock was also associated with the pathogen's presence. Multivariable logistic regression identified the selling of defrosted meat as a retailer risk factor (OR: 4.69; 95% CI: 1.31-19.97), calling for more investigation of the reported repetitive freezing-thawing processes and cold chain improvement options. At the farm-level, having a pen floor of material not easy to clean was found to increase the risk (OR: 2.31; 95%CI: 1.06-5.37). The relatively high prevalence of Campylobacter spp. across different areas and value chain nodes indicates a clear human exposure risk. The open nature of both small-scale broiler and indigenous chicken production practices with low biosecurity, hygiene and informal transactions, likely plays a role in this. While gradual improvement of farm biosecurity is recommended, risk factors identified suggest that consumer education and enforcement of basic food safety principles at the retailer end of the food continuum represent key targets for risk reduction in informal settings.

Consumer Exposure to Antimicrobial Resistant Bacteria From Food at Swiss Retail Level

Background: Antimicrobial resistance (AMR) in bacteria is an increasing health concern. The spread of AMR bacteria (AMRB) between animals and humans via the food chain and the exchange of AMR genes requires holistic approaches for risk mitigation. The AMRB exposure of humans via food is currently only poorly understood leaving an important gap for intervention design.

Method: This study aimed to assess AMRB prevalence in retail food and subsequent exposure of Swiss consumers in a systematic literature review of data published between 1996 and 2016 covering the Swiss agriculture sector and relevant imported food.

Results: Data from 313 out of 9,473 collected studies were extracted yielding 122,438 food samples and 38,362 bacteria isolates of which 30,092 samples and 8,799 isolates were AMR positive. A median AMRB prevalence of >50% was observed for meat and seafood harboring Campylobacter, Enterococcus, Salmonella, Escherichia coli, Listeria, and Vibrio spp. and to a lesser prevalence for milk products harboring starter culture bacteria. Gram-negative AMRB featured predominantly AMR against aminoglycosides, cephalosporins, fluoroquinolones, penicillins, sulfonamides, and tetracyclines observed at AMR exposures scores of levels 1 (medium) and 2 (high) for Campylobacter, Salmonella, E. coli in meat as well as Vibrio and E. coli in seafood. Gram-positive AMRB featured AMR against glycoproteins, lincosamides, macrolides and nitrofurans for Staphylococcus and Enterococcus in meat sources, Staphylococcus in seafood as well as Enterococcus and technologically important bacteria (incl. starters) in fermented or processed dairy products. Knowledge gaps were identified for AMR prevalence in dairy, plant, fermented meat and novel food products and for the role of specific indicator bacteria (Staphylococcus, Enterococcus), starter culture bacteria and their mobile genetic elements in AMR gene transfer.

Conclusion: Raw meat, milk, seafood, and certain fermented dairy products featured a medium to high potential of AMR exposure for Gram-negative and Gram-positive foodborne pathogens and indicator bacteria. Food at retail, additional food categories including fermented and novel foods as well as technologically important bacteria and AMR genetics are recommended to be better integrated into systematic One Health AMR surveillance and mitigation strategies to close observed knowledge gaps and enable a comprehensive AMR risk assessment for consumers.

A combined case-control and molecular source attribution study of human Campylobacter infections in Germany, 2011-2014

Campylobacter infection is the most commonly notified bacterial enteritis in Germany. We performed a large combined case-control and source attribution study (Nov 2011-Feb 2014) to identify risk factors for sporadic intestinal Campylobacter infections and to determine the relative importance of various animal sources for human infections in Germany. We conducted multivariable logistic regression analysis to identify risk factors. Source attribution analysis was performed using the asymmetric island model based on MLST data of human and animal/food isolates. As animal sources we considered chicken, pig, pet dog or cat, cattle, and poultry other than chicken. Consumption of chicken meat and eating out were the most important risk factors for Campylobacter infections. Additional risk factors were preparation of poultry meat in the household; preparation of uncooked food and raw meat at the same time; contact with poultry animals; and the use of gastric acid inhibitors. The mean probability of human C. jejuni isolates to originate from chickens was highest (74%), whereas pigs were a negligible source for C. jejuni infections. Human C. coli isolates were likely to originate from chickens (56%) or from pigs (32%). Efforts need to be intensified along the food chain to reduce Campylobacter load, especially on chicken meat.

Epidemiology of campylobacteriosis in Denmark 2000-2015

Campylobacter is the most frequently occurring cause of bacterial gastroenteritis in Europe. Unlike other zoonotic diseases, European-wide incidences of Campylobacter infections have increased during the past decade, resulting in a significant disease burden. In Denmark, campylobacteriosis is notifiable by laboratory and a unique registration system of electronic transfer and storage of notified Campylobacter cases linked to the national person register of age, gender and geographical location allows collection of comprehensive case data. Using national surveillance data, we describe Campylobacter infections in Denmark from 2000 to 2015, focusing on age-specific incidences, geography, seasonality and outbreaks. During the observed period, a total of 60,725 Campylobacter infections were registered with a mean annual incidence of 69.3 cases/100,000 population. From 2000 to 2014, the incidence of campylobacteriosis decreased by 20%, followed by an apparent increase of 20% from 2014 to 2015. Approximately one-third of cases were travel-related. Incidences were highest in males, young adults aged 20-29 years and children under 5 years of age. Generally, children under 10 years of age living in rural areas were at higher risk of infection. Infection patterns were seasonal with an increase from May to October, peaking in August. Outbreaks were identified each year, including four large waterborne outbreaks which all occurred following heavy rainfall events. For the most part, patterns of Campylobacter infection in Denmark during 2000 to 2015 remained remarkably constant and followed what is known about the disease with respect to demographic, temporal and spatial characteristics. To establish better targeted prevention and control measures, the current knowledge gaps regarding both Campylobacter microbiology (degree of clonal diversity and clustering) and the importance of different risk factors (food versus environment/climate) need to be filled.

The consequences of Campylobacter infection

PURPOSE OF REVIEW

The purpose of this review is to provide an update on the clinical, public health and economic consequences of Campylobacter infection.

RECENT FINDINGS

Campylobacter is a leading bacterial cause of food-related illness. Its importance is enhanced by the chronic sequelae that can result from acute infection. Recent advances include a new clinical classification system for neurological sequelae with the aim of speeding accurate diagnosis and appropriate treatment, a better understanding of the mechanisms underlying postinfectious functional gastrointestinal disorders, the emergence of Campylobacter concisus and Campylobacter showae as potential aetiological agents in inflammatory bowel disease, a new mechanism for antimicrobial resistance in campylobacters and a better appreciation of the economic costs.

SUMMARY

Campylobacter infection is very common and can lead to serious chronic sequelae and considerable personal, healthcare and societal costs.

Impact of waning acquired immunity and asymptomatic infections on case-control studies for enteric pathogens

Case-control studies of outbreaks and of sporadic cases of infectious diseases may provide a biased estimate of the infection rate ratio, due to selecting controls that are not at risk of disease. We use a dynamic mathematical model to explore biases introduced in results drawn from case-control studies of enteric pathogens by waning and boosting of immunity, and by asymptomatic infections, using Campylobacter jejuni as an example. Individuals in the population are either susceptible (at risk of infection and disease), fully protected (not at risk of either) or partially protected (at risk of infection but not of disease). The force of infection is a function of the exposure frequency and the exposure dose. We show that the observed disease odds ratios are indeed strongly biased towards the null, i.e. much lower than the infection rate ratio, and furthermore even not proportional to it. The bias could theoretically be controlled by sampling controls only from the reservoir of susceptible individuals. The population at risk is in a dynamic equilibrium, and cannot be identified as those who are not and have never experienced disease. Individual-level samples to measure protective immunity would be required, complicating the design, cost and execution of case-control studies.

Association between community socioeconomic factors, animal feeding operations, and campylobacteriosis incidence rates: Foodborne Diseases Active Surveillance Network (FoodNet), 2004-2010

Background

Campylobacter is a leading cause of foodborne illness in the United States. Campylobacter infections have been associated with individual risk factors, such as the consumption of poultry and raw milk. Recently, a Maryland-based study identified community socioeconomic and environmental factors that are also associated with campylobacteriosis rates. However, no previous studies have evaluated the association between community risk factors and campylobacteriosis rates across multiple U.S. states.

Methods

We obtained Campylobacter case data (2004–2010; n = 40,768) from the Foodborne Diseases Active Surveillance Network (FoodNet) and socioeconomic and environmental data from the 2010 Census of Population and Housing, the 2011 American Community Survey, and the 2007 U.S. Census of Agriculture. We linked data by zip code and derived incidence rate ratios using negative binomial regression models.

Results

Community socioeconomic and environmental factors were associated with both lower and higher campylobacteriosis rates. Zip codes with higher percentages of African Americans had lower rates of campylobacteriosis (incidence rate ratio [IRR]) = 0.972; 95 % confidence interval (CI) = 0.970,0.974). In Georgia, Maryland, and Tennessee, three leading broiler chicken producing states, zip codes with broiler operations had incidence rates that were 22 % (IRR = 1.22; 95 % CI = 1.03,1.43), 16 % (IRR = 1.16; 95 % CI = 0.99,1.37), and 35 % (IRR = 1.35; 95 % CI = 1.18,1.53) higher, respectively, than those of zip codes without broiler operations. In Minnesota and New York FoodNet counties, two top dairy producing areas, zip codes with dairy operations had significantly higher campylobacteriosis incidence rates (IRR = 1.37; 95 % CI = 1.22, 1.55; IRR = 1.19; 95 % CI = 1.04,1.36).

Conclusions

Community socioeconomic and environmental factors are important to consider when evaluating the relationship between possible risk factors and Campylobacter infection.

Recent Advances in Screening of Anti-Campylobacter Activity in Probiotics for Use in Poultry

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Campylobacter species involved in this infection usually include the thermotolerant species Campylobacter jejuni. The major reservoir for C. jejuni leading to human infections is commercial broiler chickens. Poultry flocks are frequently colonized by C. jejuni without any apparent symptoms. Risk assessment analyses have identified the handling and consumption of poultry meat as one of the most important sources of human campylobacteriosis, so elimination of Campylobacter in the poultry reservoir is a crucial step in the control of this foodborne infection. To date, the use of probiotics has demonstrated promising results to reduce Campylobacter colonization. This review provides recent insights into methods used for probiotic screening to reduce the prevalence and colonization of Campylobacter at the farm level. Different eukaryotic epithelial cell lines are employed to screen probiotics with an anti-Campylobacter activity and yield useful information about the inhibition mechanism involved. These in vitro virulence models involve only human intestinal or cervical cell lines whereas the use of avian cell lines could be a preliminary step to investigate mechanisms of C. jejuni colonization in poultry in the presence of probiotics. In addition, in vivo trials to evaluate the effect of probiotics on Campylobacter colonization are conducted, taking into account the complexity introduced by the host, the feed, and the microbiota. However, the heterogeneity of the protocols used and the short time duration of the experiments lead to results that are difficult to compare and draw conclusions at the slaughter-age of broilers. Nevertheless, the combined approach using complementary in vitro and in vivo tools (cell cultures and animal experiments) leads to a better characterization of probiotic strains and could be employed to assess reduced Campylobacter spp. colonization in chickens if some parameters are optimized.