Marie-Josée J. Mangen

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.

Healthcare costs of inflammatory bowel disease have shifted from hospitalisation and surgery towards anti-TNFα therapy: results from the COIN study.

Objective The introduction of anti tumour necrosis factor-α (anti-TNFα) therapy might impact healthcare expenditures, but there are limited data regarding the costs of inflammatory bowel diseases (IBD) following the introduction of these drugs. We aimed to assess the healthcare costs and productivity losses in a large cohort of IBD patients. Design Crohns disease (CD) and ulcerative colitis (UC) patients from seven university hospitals and seven general hospitals were invited to fill-out a web-based questionnaire. Cost items were derived from a 3 month follow-up questionnaire and categorised in outpatient clinic, diagnostics, medication, surgery and hospitalisation. Productivity losses included sick leave of paid and unpaid work. Costs were expressed as mean 3-month costs per patients with a 95% CI obtained using non-parametric bootstrapping. Results A total of 1315 CD patients and 937 UC patients were included. Healthcare costs were almost three times higher in CD as compared with UC, €1625 (95% CI €1476 to €1775) versus €595 (95% CI €505 to €685), respectively (p<0.01). Anti-TNFα use was the main costs driver, accounting for 64% and 31% of the total cost in CD and UC. Hospitalisation and surgery together accounted for 19% and <1% of the healthcare costs in CD and 23% and 1% in UC, respectively. Productivity losses accounted for 16% and 39% of the total costs in CD and UC. Conclusions We showed that healthcare costs are mainly driven by medication costs, most importantly by anti-TNFα therapy. Hospitalisation and surgery accounted only for a minor part of the healthcare costs.

An update to "the cost-effectiveness of rotavirus vaccination: comparative analyses for five European countries and transferability in Europe".

Cost-effectiveness analyses are usually not directly comparable between countries because of differences in analytical and modelling assumptions. We investigated the cost-effectiveness of rotavirus vaccination in five European Union countries (Belgium, England and Wales, Finland, France and the Netherlands) using a single model, burden of disease estimates supplied by national public health agencies and a subset of common assumptions. Under base case assumptions (vaccination with Rotarix, 3% discount rate, health care provider perspective, no herd immunity and quality of life of one caregiver affected by a rotavirus episode) and a cost-effectiveness threshold of euro30,000, vaccination is likely to be cost effective in Finland only. However, single changes to assumptions may make it cost effective in Belgium and the Netherlands. The estimated threshold price per dose for Rotarix (excluding administration costs) to be cost effective was euro41 in Belgium, euro28 in England and Wales, euro51 in Finland, euro36 in France and euro46 in the Netherlands.

Simulated effect of pig-population density on epidemic size and choice of control strategy for classical swine fever epidemics in The Netherlands.

We examined the importance of pig-population density in the area of an outbreak of classical swine fever (CSF) for the spread of the infection and the choice of control measures. A spatial, stochastic, dynamic epidemiological simulation model linked to a sector-level market-and-trade model for The Netherlands were used. Outbreaks in sparsely and densely populated areas were compared under four different control strategies and with two alternative trade assumptions. The obligatory control strategy required by current EU legislation was predicted to be enough to eradicate an epidemic starting in an area with sparse pig population. By contrast, additional control measures would be necessary if the outbreak began in an area with high pig density. The economic consequences of using preventive slaughter rather than emergency vaccination as an additional control measure depended strongly on the reactions of trading partners. Reducing the number of animal movements significantly reduced the size and length of epidemics in areas with high pig density. The phenomenon of carrier piglets was included in the model with realistic probabilities of infection by this route, but it made a negligible contribution to the spread of the infection.

New Methodology for Estimating the Burden of Infectious Diseases in Europe

Mirjam Kretzschmar and colleagues describe the BCoDE project, which uses a pathogen-based incidence approach to better estimate the infectious disease burden in Europe.

High impact of migration on the prevalence of chronic hepatitis B in the Netherlands.

Objectives A representative serosurveillance study (1995) resulted in an estimate of 0.2% for the HBsAg prevalence in the Netherlands. Some risk groups, especially migrants, were not well represented in the study, which probably led to an underestimation of the true HBsAg prevalence. The aim of this study was to calculate an adjusted HBsAg prevalence estimate for the total Dutch population including these risk groups. Methods According to their country of origin first-generation migrants (FGM) were classified into groups with low, intermediate and high prevalence using data from the WHO and Statistics Netherlands. The number of chronic HBsAg carriers in different age and population groups was estimated based on studies about age-specific prevalence in different countries. The number of carriers in the indigenous population was estimated using the serosurveillance study. A combination of these estimates led to an estimate of the total prevalence rate in the Netherlands. Results Nearly 10% of the Dutch population are FGM. Of these, about 18% were born in low-endemic, 71% in middle-endemic and 11% in high-endemic countries. The overall prevalence of HBsAg in FGM is estimated to be at 3.77%. Combining these results with the results of the serosurveillance study the HBsAg prevalence in the Dutch population is estimated to be between 0.32 and 0.51%, and when including injecting drug users and mentally handicapped persons the prevalence rates are 0.36 and 0.55%, respectively. Conclusion Our results show the high importance of targeting migrants and their close contacts adequately in screening programmes, vaccination and treatment for chronic hepatitis B.

Spatial and stochastic simulation to compare two emergency-vaccination strategies with a marker vaccine in the 1997/1998 Dutch Classical Swine Fever epidemic.

Two alternative emergency-vaccination strategies with a marker vaccine that could have been applied in the 1997/1998 Dutch Classical Swine Fever (CSF) epidemic were evaluated in a modified spatial, temporal and stochastic simulation model: InterCSF. In strategy 1, vaccination would be applied only to overcome a shortage in destruction capacities. Destruction of all pigs on vaccinated farms distinguishes this strategy from strategy 2, which assumes intra-Community trade of vaccinated pig meat. InterCSF simulates the spread of CSF between farms through local spread and three contact types. Disease spread is affected by control measures implemented through different mechanisms. Economic results were generated by a separate model that calculated the direct costs (including the vaccination costs) and consequential losses for farmers and related industries subjected to control measures. The comparison (using epidemiological and economic results) between the different emergency-vaccination strategies with an earlier simulated preventive-slaughter scenario led to some general conclusions on the Dutch CSF epidemic. Both emergency-vaccination strategies were hardly more efficient than the non-vaccination scenario. The intra-Community trade strategy (vaccination-strategy 2) was the least costly of all three scenarios.

The pathogen- and incidence-based DALY approach: An appropriated methodology for estimating the burden of infectious diseases

In 2009, the European Centre for Disease Prevention and Control initiated the ‘Burden of Communicable Diseases in Europe (BCoDE)’ project to generate evidence-based and comparable burden-of-disease estimates of infectious diseases in Europe. The burden-of-disease metric used was the Disability-Adjusted Life Year (DALY), composed of years of life lost due to premature death (YLL) and due to disability (YLD). To better represent infectious diseases, a pathogen-based approach was used linking incident cases to sequelae through outcome trees. Health outcomes were included if an evidence-based causal relationship between infection and outcome was established. Life expectancy and disability weights were taken from the Global Burden of Disease Study and alternative studies. Disease progression parameters were based on literature. Country-specific incidence was based on surveillance data corrected for underestimation. Non-typhoidal Salmonella spp. and Campylobacter spp. were used for illustration. Using the incidence- and pathogen-based DALY approach the total burden for Salmonella spp. and Campylobacter spp. was estimated at 730 DALYs and at 1,780 DALYs per year in the Netherlands (average of 2005–2007). Sequelae accounted for 56% and 82% of the total burden of Salmonella spp. and Campylobacter spp., respectively. The incidence- and pathogen-based DALY methodology allows in the case of infectious diseases a more comprehensive calculation of the disease burden as subsequent sequelae are fully taken into account. Not considering subsequent sequelae would strongly underestimate the burden of infectious diseases. Estimates can be used to support prioritisation and comparison of infectious diseases and other health conditions, both within a country and between countries.

Is it cost-effective to introduce rotavirus vaccination in the Dutch national immunization program?

This study assessed whether the inclusion of two rotavirus (RV) vaccines in the Dutch national immunization programme is cost-effective. Costs and outcomes in unvaccinated and vaccinated populations are compared for a time period of 20 years. In the baseline, assuming competitive market forces in relation to vaccine costs, Rotarix is more cost-effective than RotaTeq, resulting in a cost-utility ratio (CUR) of euro 53,000 per DALY (third payer perspective) and euro 49,000 per DALY (societal perspective), but both considered as being not cost-effective. Vaccine-related costs, annual epidemic-size, and indirect protection are the major factors that determine cost-effectiveness of RV vaccination.

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 doctors 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).