Systematic review of foodborne burden of disease studies: Quality assessment of data and methodology

Burden of disease (BoD) studies aim to identify the public health impact of different health problems and risk factors. To assess BoD, detailed knowledge is needed on epidemiology, disability and mortality in the population under study. This is particularly challenging for foodborne disease, because of the multitude of causative agents and their health effects. The purpose of this study is to systematically review the methodology of foodborne BoD studies. Three key questions were addressed: 1) which data sources and approaches were used to assess mortality, morbidity and disability?, 2) which methodological choices were made to calculate Disability Adjusted Life Years (DALY), and 3) were uncertainty analyses performed and if so, how? Studies (1990-June 2012) in international peer-reviewed journals and grey literature were identified with main inclusion criteria being that the study assessed disability adjusted life years related to foodborne disease. Twenty-four studies met our inclusion criteria. To assess incidence or prevalence of foodborne disease in the population, four approaches could be distinguished, each using a different data source as a starting point, namely 1) laboratory-confirmed cases, 2) cohort or cross-sectional data, 3) syndrome surveillance data and 4) exposure data. Considerable variation existed in BoD methodology (e.g. disability weights, discounting, age-weighting). Almost all studies analyzed the effect of uncertainty as a result of possible imprecision in the parameter values. Awareness of epidemiological and methodological rigor between foodborne BoD studies using the DALY approach is a critical priority for advancing burden of disease studies. Harmonization of methodology that is used and of modeling techniques and high quality data can enlarge the detection of real variation in DALY outcomes between pathogens, between populations or over time. This harmonization can be achieved by identifying substantial data gaps and uncertainty and establish which sequelae of foodborne disease agents should be included in BoD calculations

Impact of infectious diseases on population health using incidence-based disability-adjusted life years (DALYs)

Background and aims: The Burden of Communicable Diseases in Europe (BCoDE) study aimed to calculate disability-adjusted life years (DALYs) for 31 selected diseases in the European Union (EU) and European Economic Area (EEA). Methods: DALYs were estimated using an incidence-based and pathogen-based approach. Incidence was estimated through assessment of data availability and quality, and a correction was applied for under-estimation. Calculation of DALYs was performed with the BCoDE software toolkit without applying time discounting and age-weighting. Results: W

Methodological framework for World Health Organization estimates of the global burden of foodborne disease

Background: The Foodborne Disease Burden Epidemiology Reference Group (FERG) was established in 2007 by the World Health Organization to estimate the global burden of foodborne diseases (FBDs). This paper describes the methodological framework developed by FERG's Computational Task Force to transform epidemiological information into FBD burden estimates. Methods and Findings: The global and regional burden of 31 FBDs was quantified, along with limited estimates for 5 other FBDs, using Disability-Adjusted Life Years in a hazard- and incidence-based approach. To accomplish this task, the following workflow was defined: outline of disease models and collection of epidemiological data; design and completion of a database template; development of an imputation model; identification of disability weights; probabilistic burden assessment; and estimating the proportion of the disease burden by each hazard that is attributable to exposure by food (i.e., source attribution). All computations were performed in R and the different functions were compiled in the R package 'FERG'. Traceability and transparency were ensured by sharing results and methods in an interactive way with all FERG members throughout the process. Conclusions: We developed a comprehensive framework for estimating the global burden of FBDs, in which methodological simplicity and transparency were key elements. All the tools developed have been made available and can be translated into a user-friendly national toolkit for studying and monitoring food safety at the local level

Cost of illness and disease burden in the Netherlands due to infections with Shiga toxin-producing Escherichia coli O157

Infections with Shiga toxin-producing Escherichia coli O157 (STEC O157) are associated with hemorrhagic colitis, hemolytic uremic syndrome (HUS), and end-stage renal disease (ESRD). In the present study, we extend previous estimates of the burden of disease associated with STEC O157 with estimates of the associated cost of illness in The Netherlands. A secondorder stochastic simulation model was used to calculate disease burden as disability-adjusted life years (DALYs) and cost of illness (including direct health care costs and indirect non-health care costs). Future burden and costs are presented undiscounted and discounted at annual percentages of 1.5 and 4%, respectively. Annually, approximately 2.100 persons per year experience symptoms of gastroenteritis, leading to 22 cases of HUS and 3 cases of ESRD. The disease burden at the population level was estimated at 133 DALYs (87 DALYs discounted) per year. Total annual undiscounted and discounted costs of illness due to STEC O157 infection for the Dutch society were estimated at €9.1 million and €4.5 million, respectively. Average lifetime undiscounted and discounted costs per case were both €126 for diarrheal illness, both €25,713 for HUS, and €2.76 million and €1.22 million, respectively, for ESRD. The undiscounted and discounted costs per case of diarrheal disease including sequelae were €4,132 and €2,131 , respectively. Compared with other foodborne pathogens, STEC O157 infections result in relatively low burden and low annual costs at the societal level, but the burden and costs per case are high

Infectious disease risks associated with occupational exposure: A systematic review of the literature

Employees in different types of work may be intentionally or accidentally exposed to biological agents. Improved risk assessment is needed to identify opportunities to prevent work-related infectious disease. The objective of the current study was to perform a systematic literature review of work-related infectious disease to assist in the identification of occupational infectious disease risks. A literature search of papers on work-related infectious disease published between 1999 and 2008 yielded 1239 papers of which 242 met the selection criteria and were included in the review. The results of the systematic literature review were arranged in a matrix of occupational groups and exposure pathways. Increased risk from infectious diseases appeared to be concentrated in specific professions. Healthcare workers, workers in contact with animals, laboratory workers and refuse workers seem to have the highest risk of infection by a variety of pathogens. However, pathogens reported to be associated with closely related professions were different, indicating qualitative under-reporting. Arranging the results of this systematic review on work-related infectious diseases in a matrix of occupational groups and exposure pathways allowed the reliable identification of exposure hazards for specific occupational groups beyond currently reported diseases

Beyond the neglect of psychological consequences: Post-traumatic stress disorder increases the non-fatal burden of injury by more than 50%

Background Psychological consequences such as posttraumatic stress disorder (PTSD) are currently neglected in burden-of-injury calculations. Aim To assess the disease burden of PTSD due to unintentional injury and compare this health loss with physical injury consequences. Methods From literature sources, the prevalence of PTSD at four follow-up periods (12 months) was estimated. The uncertainty of the estimated PTSD prevalence was modelled by a Bayesian approach. The prevalence rates were then linked to national data on unintentional injury, disability weights and duration to estimate the incidence and disability-adjusted life years (DALY) resulting from PTSD in addition to physical injury consequences. Results The data suggest that PTSD prevalence among injury victims decreases over time. The average PTSD prevalence at <3 months follow-up was 21% (90% credibility interval (CI) 17% to 24%) for patients presenting at the emergency department and 30% (90% CI 27% to 33%) for patients who were hospitalised, tapering down after 12 months to 4% (90% CI 3% to 5%) and 6% (90% CI 4% to 10%), respectively. These estimates translate into 191 000 (90% CI 161 000 to 222 000) cases of PTSD per year in the Dutch population (1.2%) due to unintentional injury. Including PTSD increases the non-fatal burden of disease of unintentional injuries by 53% (from 116 000 to 178 000 DALYs (90% CI 150 000 to 217 000)). Conclusions Ignoring PTSD in burden-of-injury studies results in a considerable underestimation of the burden of injury. This may affect resource allocation and the identification of important prevention priorities

Immunity to Campylobacter: its role in risk assessment and epidemiology

Acquired immunity is an important factor in the epidemiology of campylobacteriosis in the developing world, apparently limiting symptomatic infection to children of less than two years. However, also in developed countries the highest incidence is observed in children under five years and the majority of Campylobacter infections are asymptomatic, which may be related to the effects of immunity and/or the ingested doses. Not accounting for immunity in epidemiological studies may lead to biased results due to the misclassification of Campylobacter-exposed but apparently healthy persons as unexposed. In risk assessment studies, health risks may be overestimated when immunity is neglected