Time trends of positivity rates from foodborne pathogen testing in Switzerland, 2003 to 2012.

BACKGROUND: Campylobacteriosis and salmonellosis are important foodborne diseases in Europe, including in Switzerland. In 2014, notification rates for Switzerland were 92.9 per 100 000 population for campylobacteriosis and 15.2 per 100 000 population for salmonellosis. These notification rates originate from laboratory-based surveillance whereby positive test results are reported to the National Notification System for Infectious Diseases. Consequently, notification rates do not directly correspond to the disease burden among the population as the number of positive tests depends on patients' healthcare-seeking behaviour, stool sampling rates and other factors. METHODS: We assessed laboratory positivity rates (proportion of positive tests among all tests performed) of diagnostic tests for Campylobacter and Salmonella from five private laboratories in Switzerland between 2003 and 2012. We analysed demographic characteristics, temporal and spatial distribution of test numbers and positivity rates. Predictors for a positive test and disease seasonality were assessed with logistic regression analyses. RESULTS: A total of 135 122 (13 095 positive) Campylobacter tests and 136 997 (2832 positive) Salmonella tests were obtained with positive tests corresponding to 20.4% and 17.2% of notified campylobacteriosis and salmonellosis cases, respectively. The number of tests conducted annually increased for both pathogens by 51% from 2003 to 2012. Annual positivity rates of Campylobacter increased from 7.6 to 11.1% and rates of Salmonella decreased from 2.7 to 1.5%. The largest increases in annual Campylobacter positivity rates were observed for patients older than 85 years (+193.7%), followed by children aged 5-9 years (+131.9%). Positivity rates and test numbers for both diseases by month or calendar week showed a distinct seasonality, with peak rates for Salmonella occurring in autumn and for Campylobacter in summer and at the turn of the year. These findings were independent of patients' age and sex. CONCLUSIONS: Both positivity rates and notification rates showed increasing trends for Campylobacter and decreasing trends for Salmonella, suggesting that these trends reflect changes in disease epidemiology at population level. The continuous assessment of positivity rates remains important to appropriately interpret changes observed in the notification system especially considering the increasing use of multiplex polymerase chain reaction test panels where multiple pathogens are tested simultaneously.

Acute gastroenteritis in primary care: a longitudinal study in the Swiss Sentinel Surveillance Network, Sentinella.

PURPOSE: Acute gastroenteritis (AG) leads to considerable burden of disease, health care costs and socio-economic impact worldwide. We assessed the frequency of medical consultations and work absenteeism due to AG at primary care level, and physicians' case management using the Swiss Sentinel Surveillance Network "Sentinella". METHODS: During the 1-year, longitudinal study in 2014, 172 physicians participating in "Sentinella" reported consultations due to AG including information on clinical presentation, stool diagnostics, treatment, and work absenteeism. RESULTS: An incidence of 2146 first consultations due to AG at primary care level per 100,000 inhabitants in Switzerland was calculated for 2014 based on reported 3.9 thousand cases. Physicians classified patients' general condition at first consultation with a median score of 7 (1 = poor, 10 = good). The majority (92%) of patients received dietary recommendations and/or medical prescriptions; antibiotics were prescribed in 8.5%. Stool testing was initiated in 12.3% of cases; more frequently in patients reporting recent travel. Among employees (15-64 years), 86.3% were on sick leave. Median duration of sick leave was 4 days. CONCLUSIONS: The burden of AG in primary care is high and comparable with that of influenza-like illness (ILI) in Switzerland. Work absenteeism is substantial, leading to considerable socio-economic impact. Mandatory infectious disease surveillance underestimates the burden of AG considering that stool testing is not conducted routinely. While a national strategy to reduce the burden of ILI exists, similar comprehensive prevention efforts should be considered for AG.

The recurrent campylobacteriosis epidemic over Christmas and New Year in European countries, 2006-2014.

OBJECTIVE: Campylobacteriosis is the most frequently reported foodborne disease in Europe with a notification rate of 71 per 100,000 population in the European Union in 2014. Surveillance data show a clear seasonality whereby case numbers peak during summer months in entire Europe and at the turn of the year, especially in Germany and Switzerland. A detailed description of European surveillance data by country at the turn of the year was missing so far. The objectives of the presented work were to describe national surveillance data of The European Surveillance System for 14 countries during winter times and to generate hypotheses for the observed seasonality of campylobacteriosis cases. RESULTS: The analysis included 317,986 cases notified between calendar weeks 45 and 8 of winter seasons 2006/2007-2013/2014. Winter peaks in weekly case notifications and notification rates were observed for Austria, Belgium, Finland, Germany, Luxembourg, The Netherlands, Switzerland and Sweden while for Denmark, France, Ireland, Italy, Norway and the United Kingdom no unusual increase was observed. Generally, weekly notification rates peaked in calendar week 1 or 2 after a strong decline in the last week of December and reached values of a multiple of the observed notification rates in the weeks before or after the peak e.g. up to 6.5 notifications per 100,000 population per week in Luxembourg. Disease onset of cases notified during winter peaks occurred predominantly in calendar weeks 52 and 1 and point towards risk exposures around Christmas and New Year. The consumption of meat fondue or table top grilling poses such a risk and is popular in many countries with an observed winter peak. Additionally, increased travel activities over the festive season could foster campylobacteriosis transmission. Surveillance artefacts (e.g. reporting delays due to public holidays) should be excluded as causes for country-specific winter peaks before investigating risk exposures.

How can patients and their physicians contribute to an outbreak investigation? Experiences from a nationwide listeriosis outbreak in Switzerland.

QUESTIONS UNDER STUDY/PRINCIPLES: Gathering patient information to contain an outbreak of Listeria monocytogenes is difficult because of the patients' severe illness or death. Extending the range of interviewees to acquire epidemiological data can thus be important to maximise information. METHODS: We built the current analysis on a case-case outbreak investigation conducted during a Swiss listeriosis outbreak between 30 January and 11 May 2014, including 31 patients with confirmed L. monocytogenes infection. We interviewed treating physicians and patients or their next of kin to gather information on clinical aspects, eating habits and food consumption. We compared the different information sources with regards to their potential to provide specific, complete and rapid information on the affected population and their food consumption history. RESULTS: We obtained a 100% response rate among physicians, providing detailed information on the affected population by describing health status, underlying conditions, and signs and symptoms. Detailed information on food history could not be obtained from physicians, making the information vague and unspecific. Less than 50% of patients could be interviewed, limiting our information base. Nevertheless, patient information on the food history was sufficiently detailed and helped to identify the outbreak source CONCLUSIONS: Outbreak investigation teams confronted with limited information from patients and with small numbers of cases can enhance information on the affected population and the outbreak source by combining information from physicians and patients. Physicians provided comprehensive information on signs and symptoms, underlying conditions and the general health status. Patients remain vital to provide detailed information on the food consumption history.

A tradition and an epidemic: determinants of the campylobacteriosis winter peak in Switzerland.

Campylobacteriosis is the most frequently reported food borne infection in Switzerland. We investigated determinants of infections and illness experience in wintertime. A case-control study was conducted in Switzerland between December 2012 and February 2013. Cases were recruited among laboratory-confirmed campylobacteriosis patients. Population-based controls were matched according to age group, sex and canton of residence. We determined risk factors associated with campylobacteriosis, and help seeking behaviour and illness perception. The multivariable analysis identified two factors associated with an increased risk for campylobacteriosis: consumption of meat fondue (matched odds ratio [mOR] 4.0, 95% confidence interval [CI] 2.3-7.1) and travelling abroad (mOR 2.7, 95% CI 1.1-6.4). Univariable analysis among meat fondue consumers revealed chicken as the type of meat with the highest risk of disease (mOR 3.8, 95% CI 1.1-13.5). Most frequently reported signs and symptoms among patients were diarrhoea (98%), abdominal pain (81%), fever (66%), nausea (44%) and vomiting (34%). The median perceived disease severity was 8 on a 1-to-10 rating scale. Patients reported a median duration of illness of 7 days and 14% were hospitalised. Meat fondues, mostly "Fondue chinoise", traditionally consumed during the festive season in Switzerland, are the major driver of the epidemic campylobacteriosis peak in wintertime. At these meals, individual handling and consumption of chicken meat may play an important role in disease transmission. Laboratory-confirmed patients are severely ill and hospitalisation rate is considerable. Public health measures such as decontamination of chicken meat and improved food handling behaviour at the individual level are urgently needed.