Eating a national festive dish is a risk factor for human campylobacteriosis in Switzerland, according to researchers.
Findings highlight the importance of food hygiene for chicken preparation and consumption at meat fondues.
The “Fondue chinoise” comprises sliced raw meat being individually handled and boiled in a family-shared broth hotpot.
The main risks are chicken meat contaminated with Campylobacter and possibilities of and occasions for cross-contamination and ingestion of bacteria and the infection risk is exacerbated through individual food-handling at the table.
Researchers assessed determinants for Campylobacter infections in wintertime in Switzerland with a case–control study design among laboratory-confirmed campylobacteriosis patients.
In 2012, the notification rate was 106 cases per 100,000 population corresponding to 8,567 laboratory confirmed cases.
Summer and winter peaks
In Switzerland and Germany, seasonal patterns show two distinct peaks: in summer and in winter.
This could be because in Switzerland, suspected causes for peaks include handling of raw and consumption of undercooked meat from barbecuing and from preparing a traditional meat fondue, a festive Christmas and New Year’s dish, which involves handling of raw meet by the consumer.
Objectives were to investigate determinants of the campylobacteriosis winter peak in Switzerland and to elucidate illness perception, symptomatology, and help seeking patterns of campylobacteriosis patients.
The Swiss Federal Office of Public Health, with the Swiss Federal Food Safety and Veterinary Office commissioned Swiss TPH to perform a case control study to investigate the festive season increase.
A case-control study recruiting prospectively laboratory-confirmed campylobacteriosis cases and population-based controls was conducted between December 2012 and February 2013.
A total of 303 campylobacteriosis case notifications were received, after exclusion of cases <5 years and non-Swiss residency, 289 cases and 898 controls were invited to participate.
Chicken increases risk factor
Among foods eaten during the week prior to disease onset, meat consumption was identified as a significant risk factor but the only type significantly associated with an increased risk was chicken.
None of the other meat types consumed during fondue dishes were associated with Campylobacter infections.
Eating raw vegetables was significantly associated with a decreased risk and eating dried and smoked meat and ham were associated with a decreased risk.
The consumption of meat fondue was identified as a strong risk factor and the most frequently eaten meat fondue variant, the so-called “Fondue chinoise”, was also strongly associated.
Disease onset dates peaked 2–3 days after dinners around Christmas and New Year.
This is in line with the incubation period of two to five days. More than 50% of Campylobacter-related gastroenteritis can be attributed to the consumption of meat fondue during the study period.
Hospitalisation rate was 14% and was increased among patients ≥60 years (33%) with half lasting at least three nights.
Researchers observed that meat fondue eaters who put their raw and cooked meat on the same plate were more likely to suffer from campylobacteriosis. The use of a compartmented or using two separate plates appeared to be protective and has been previously recommended.
Potential preventive risk reduction measures could be applied upstream, through decontamination at slaughter using peracetic acid resulting in a decreased bacterial load at retail level or freezing of chicken meat before reaching retail.
Downstream risk prevention measures could include improving consumer awareness in handling raw chicken meat additionally to the current hygiene notice on Swiss chicken meat packages.
Source: European Journal of Epidemiology
Online ahead of print, DOI: 10.1007/s10654-014-9917-0
“A tradition and an epidemic: determinants of the campylobacteriosis winter peak in Switzerland”
Authors: Philipp Justus Bless, Claudia Schmutz, Kathrin Suter, Marianne Jost, Jan Hattendorf, Mirjam Mäusezahl-Feuz and Daniel Mäusezahl