Rapid assessment of regional SARS-CoV-2 community transmission through a convenience sample of healthcare workers, the Netherlands, March 2020.

To rapidly assess possible community transmission in Noord-Brabant, the Netherlands, healthcare workers (HCW) with mild respiratory complaints and without epidemiological link (contact with confirmed case or visited areas with active circulation) were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Within 2 days, 1,097 HCW in nine hospitals were tested; 45 (4.1%) were positive. Of six hospitals with positive HCW, two accounted for 38 positive HCW. The results informed local and national risk management.

Hepatitis A outbreak disproportionately affecting men who have sex with men (MSM) in the European Union and European Economic Area, June 2016 to May 2017.

Between 1 June 2016 and 31 May 2017, 17 European Union (EU) and European Economic Area countries reported 4,096 cases associated with a multi-country hepatitis A (HA) outbreak. Molecular analysis identified three co-circulating hepatitis A virus (HAV) strains of genotype IA: VRD_521_2016, V16-25801 and RIVM-HAV16-090. We categorised cases as confirmed, probable or possible, according to the EU outbreak case definitions. Confirmed cases were infected with one of the three outbreak strains. We investigated case characteristics and strain-specific risk factors for transmission. A total of 1,400 (34%) cases were confirmed; VRD_521_2016 and RIVM-HAV16-090 accounted for 92% of these. Among confirmed cases with available epidemiological data, 92% (361/393) were unvaccinated, 43% (83/195) travelled to Spain during the incubation period and 84% (565/676) identified as men who have sex with men (MSM). Results depict an HA outbreak of multiple HAV strains, within a cross-European population, that was particularly driven by transmission between non-immune MSM engaging in high-risk sexual behaviour. The most effective preventive measure to curb this outbreak is HAV vaccination of MSM, supplemented by primary prevention campaigns that target the MSM population and promote protective sexual behaviour.

The economic burden of a Salmonella Thompson outbreak caused by smoked salmon in the Netherlands, 2012-2013.

Background: In 2012, the Netherlands experienced the most extensive food-related outbreak of Salmonella ever recorded. It was caused by smoked salmon contaminated with Salmonella Thompson during processing. In total, 1149 cases of salmonellosis were laboratory confirmed and reported to RIVM. Twenty percent of cases was hospitalised and four cases were reported to be fatal. The purpose of this study was to estimate total costs of the Salmonella Thompson outbreak. Methods: Data from a case-control study were used to estimate the cost-of-illness of reported cases (i.e. healthcare costs, patient costs and production losses). Outbreak control costs were estimated based on interviews with staff from health authorities. Using the Dutch foodborne disease burden and cost-of-illness model, we estimated the number of underestimated cases and the associated cost-of-illness. Results: The estimated number of cases, including reported and underestimated cases was 21 123. Adjusted for underestimation, the total cost-of-illness would be €6.8 million (95% CI €2.5-€16.7 million) with productivity losses being the main cost driver. Adding outbreak control costs, the total outbreak costs are estimated at €7.5 million. Conclusion: In the Netherlands, measures are taken to reduce salmonella concentrations in food, but detection of contamination during food processing remains difficult. As shown, Salmonella outbreaks have the potential for a relatively high disease and economic burden for society. Early warning and close cooperation between the industry, health authorities and laboratories is essential for rapid detection, control of outbreaks, and to reduce disease and economic burden.

Cost-of-illness and disease burden of food-related pathogens in the Netherlands, 2011.

To inform risk management decisions on control and prevention of food-related disease, both the disease burden expressed in Disability Adjusted Life Years (DALY) and the cost-of-illness of food-related pathogens are estimated and presented. Disease burden of fourteen pathogens that can be transmitted by food, the environment, animals and humans was previously estimated by Havelaar et al. (2012). In this paper we complement these by cost-of-illness estimates. Together, these present a complete picture of the societal burden of food-related diseases. Using incidence estimates for 2011, community-acquired non-consulting cases, patients consulting their general practitioner, hospitalized patients and the incidence of sequelae and fatal cases, estimates were obtained for DALYs, direct healthcare costs (e.g. costs for doctor's fees, hospitalizations and medicines), direct non-healthcare costs (e.g. travel costs to and from the doctor), indirect non-healthcare costs (e.g. productivity loss, special education) and total costs. The updated disease burden for 2011 was equal to 13,940 DALY/year (undiscounted) or 12,650 DALY/year (discounted at 1.5%), and was of the same magnitude as previous estimates. At the population-level thermophilic Campylobacter spp., Toxoplasma gondii and rotavirus were associated with the highest disease burden. Perinatal listeriosis infection was associated with the highest DALY per symptomatic case. The total cost-of-illness in 2011 of fourteen food-related pathogens and associated sequelae was estimated at € 468 million/year, if undiscounted, and at € 416 million/year if discounted by 4%. Direct healthcare costs accounted for 24% of total costs, direct non-healthcare costs for 2% and indirect non-healthcare costs for 74% of total costs. At the population-level, norovirus had the highest total cost-of-illness in 2011 with € 106 million/year, followed by thermophilic Campylobacter spp. (€ 76 million/year) and rotavirus (€ 73 million/year). Cost-of-illness per infected case varied from € 150 for Clostridium perfringens intoxications to € 275,000 for perinatal listeriosis. Both incident cases and fatal cases are more strongly correlated with COI/year than with DALY/year. More than 40% of all cost-of-illness and DALYs can be attributed to food, in total € 168 million/year and 5,150 DALY/year for 2011. Beef, lamb, pork and poultry meat alone accounted for 39% of these costs. Products of animal origin accounted for € 86 million/year (or 51% of the costs attributed to food) and 3,320 DALY/year (or 64% of the disease burden attributed to food). Among the pathogens studied Staphylococcus aureus intoxications accounted for the highest share of costs attributed to food (€ 47.1 million/year), followed by Campylobacter spp. (€ 32.0 million/year) and norovirus (€ 17.7 million/year).

Extension of traditional infectious disease surveillance with a repeated population survey.

BACKGROUND: Public health surveillance is an important tool for monitoring cases of infectious diseases. Identification of risk factors requires the comparison of exposure between cases and controls. However, standard surveillance systems do not routinely collect information on controls. METHODS: Since 2008, we have extended the surveillance of infectious diseases in The Netherlands with a repeated population survey. This survey is based on the thrice-yearly administration of a questionnaire about potential risk factors for several gastrointestinal, foodborne and respiratory infections to a representative, dynamic sample of the Dutch population. The questionnaire contains questions similar to those used for interviewing cases. RESULTS: Over 14 mailing rounds, 4926 persons were approached with a response of 36%, with a small underrepresentation of men, young people, people living in large cities and persons with both parents born outside The Netherlands. Costs per completed questionnaire were around 15 euro. Muscle/joint pain in the past 4 weeks was the most reported symptom (44%), followed by running nose (39%) and headache (32%); 5.6% reported gastroenteritis, reflecting an incidence of 997 episodes per 1000 person-years. CONCLUSIONS: Extending traditional surveillance with a repeated population survey offers the unique opportunity to gather data for a multitude of purposes. The survey already has been used in two outbreak investigations and two case-control studies. It is cost-effective and may provide novel epidemiological insights towards risk group and risk factor identification and characterization for a variety of infectious diseases. The survey will be continued and expanded in use.

Disease burden of foodborne pathogens in the Netherlands, 2009.

To inform risk management decisions on control, prevention and surveillance of foodborne disease, the disease burden of foodborne pathogens is estimated using Disability Adjusted Life Years as a summary metric of public health. Fourteen pathogens that can be transmitted by food are included in the study (four infectious bacteria, three toxin-producing bacteria, four viruses and three protozoa). Data represent the burden in the Netherlands in 2009. The incidence of community-acquired non-consulting cases, patients consulting their general practitioner, those admitted to hospital, as well as the incidence of sequelae and fatal cases is estimated using surveillance data, cohort studies and published data. Disease burden includes estimates of duration and disability weights for non-fatal cases and loss of statistical life expectancy for fatal cases. Results at pathogen level are combined with data from an expert survey to assess the fraction of cases attributable to food, and the main food groups contributing to transmission. Among 1.8 million cases of disease (approx. 10,600 per 100,000) and 233 deaths (1.4 per 100,000) by these fourteen pathogens, approximately one-third (680,000 cases; 4100 per 100,000) and 78 deaths (0.5 per 100,000) are attributable to foodborne transmission. The total burden is 13,500 DALY (82 DALY per 100,000). On a population level, Toxoplasma gondii, thermophilic Campylobacter spp., rotaviruses, noroviruses and Salmonella spp. cause the highest disease burden. The burden per case is highest for perinatal listeriosis and congenital toxoplasmosis. Approximately 45% of the total burden is attributed to food. T. gondii and Campylobacter spp. appear to be key targets for additional intervention efforts, with a focus on food and environmental pathways. The ranking of foodborne pathogens based on burden is very different compared to when only incidence is considered. The burden of acute disease is a relatively small part of the total burden. In the Netherlands, the burden of foodborne pathogens is similar to the burden of upper respiratory and urinary tract infections.