An approach for developing a national estimate of waterborne disease due to drinking water and a national estimate model application

In this paper, the US Environmental Protection Agency (EPA) presents an approach and a national estimate of drinking water related endemic acute gastrointestinal illness (AGI) that uses information from epidemiologic studies. There have been a limited number of epidemiologic studies that have measured waterborne disease occurrence in the United States. For this analysis, we assume that certain unknown incidence of AGI in each public drinking water system is due to drinking water and that a statistical distribution of the different incidence rates for the population served by each system can be estimated to inform a mean national estimate of AGI illness due to drinking water. Data from public water systems suggest that the incidence rate of AGI due to drinking water may vary by several orders of magnitude. In addition, data from epidemiologic studies show AGI incidence due to drinking water ranging from essentially none (or less than the study detection level) to a rate of 0.26 cases per person-year. Considering these two perspectives collectively, and associated uncertainties, EPA has developed an analytical approach and model for generating a national estimate of annual AGI illness due to drinking water. EPA developed a national estimate of waterborne disease to address, in part, the 1996 Safe Drinking Water Act Amendments. The national estimate uses best available science, but also recognizes gaps in the data to support some of the model assumptions and uncertainties in the estimate. Based on the model presented, EPA estimates a mean incidence of AGI attributable to drinking water of 0.06 cases per year (with a 95% credible interval of 0.02-0.12). The mean estimate represents approximately 8.5% of cases of AGI illness due to all causes among the population served by community water systems. The estimated incidence translates to 16.4 million cases/year among the same population. The estimate illustrates the potential usefulness and challenges of the approach, and provides a focus for discussions of data needs and future study designs. Areas of major uncertainty that currently limit the usefulness of the approach are discussed in the context of the estimate analysis.     

Cost of illness in the 1993 waterborne Cryptosporidium outbreak,Milwaukee, Wisconsin

To assess the total medical costs and productivity losses associated with the 1993 waterborne outbreak of cryptosporidiosis in Milwaukee, Wisconsin, including the average cost per person with mild, moderate, and severe illness, we conducted a retrospective cost-of-illness analysis using data from 11 hospitals in the greater Milwaukee area and epidemiologic data collected during the outbreak. The total cost of outbreak-associated illness was 96.2 million US dollars: 31.7 million US dollars in medical costs and 64.6 million US dollars in productivity losses. The average total costs for persons with mild, moderate, and severe illness were 116 US dollars, 47 US dollars, and 7,808 US dollars, respectively. The potentially high cost of waterborne disease outbreaks should be considered in economic decisions regarding the safety of public drinking water supplies.     

Estimating the burden and cost of infectious intestinal disease in the Maltese community

The aim of this study was to estimate the burden of infectious intestinal disease (IID) and cost of illness at the community level from a societal aspect. A retrospective, age-stratified cross-sectional telephone study was carried out in Malta in 2004-2005. The number of cases, resources used and cost of resources were computed. The resources involved direct costs (health-care services, stool culture tests, medicines and personal costs) and indirect costs (costs from lost employment by cases and caregivers). This study estimated 0.421 (95% CI 0.092-0.771) separate episodes of IID per person per year in Malta which corresponds to 164 471 (95% CI 35 941-301 205) episodes of IID per year or 450 (95% CI 98-825) episodes of IID each day. The largest proportion of cost is due to provision of health-care services with euro10 454 901 [Maltese liri (Lm) 4 558 970] per year; followed by euro963 295 (Lm 2 209 393) in lost productivity; euro1 286 286 (Lm 561 078) in medicines; euro152 335 (Lm 66 452) in stool culture testing and euro71 487 (Lm 31 183) in personal costs, giving a total cost of illness of over euro16 million (7 million Lm) per year. The burden and cost of IID are high enough to justify efforts to control the illness. Such estimates are important to assess the cost-effectiveness of proposed specific interventions.     

Cost of illness of invasive meningococcal disease caused by serogroup B Neisseria meningitidis in Spain

IntroductionInvasive meningococcal disease (IMD) is a severe infectious disease, mainly affecting children under 5 years, associated with long-term physical, neurological and psychological sequelae. In Spain, most IMD cases are caused by meningococcal serogroup B (MenB). This study estimates its economic burden from a societal perspective in Spain.MethodsA previously published bottom-up, model-based incidence costing approach by Scholz et al. (2019) to estimate the economic burden of MenB in Germany was adapted to the Spanish setting. Diagnosis and age-related costs for a hypothetical Spanish cohort were calculated over a lifetime horizon. Official Spanish databases, literature and expert opinion were used as data sources. The costs were updated to 2019 prices, and a 3% discount rate was applied. Direct costs related to the acute IMD phase, long-term sequelae, rehabilitation and public health response were considered. Indirect costs included productivity losses and premature mortality and were calculated using the human-capital approach (HCA) and friction-cost approach (FCA). Deterministic and probabilistic sensitivity analyses were also performed.ResultAt base-case, the total cost for a cohort of 142 patients (2017–2018 period) was €4.74 million (€33,484/case) using the FCA and €13.14 million (€92,768/case) using the HCA. Direct costs amounted to €4.65 million (€32,765/case). Sequelae costs represented 62.46% of the total cost using the FCA and 77.63% using the HCA. Deterministic sensitivity analysis showed that variation of ± 20% in the input parameter values (population, epidemiology, productivity, costs) had the greatest influence on the base-case results, and the probabilistic sensitivity analysis showed the probability of fitting base-case estimates was > 99%, both for FCA and HCA.DiscussionMenB IMD is an uncommon but severe disease, with a high economic burden for Spanish society. The elevated costs per IMD case reflect its severity in each patient suffering this disease, especially due to the development of sequelae.     

The societal cost of vaccine refusal: A modelling study using measles vaccination as a case study

BackgroundIncreasing vaccine hesitancy and refusal poses a challenge to public health as even small reductions in vaccine uptake can result in large outbreaks of infectious diseases. Here we estimate the societal costs of vaccine refusal using measles as a case study.MethodsWe developed a compartmental metapopulation model of measles transmission to explore how the changes in the size and level of social mixing between populations that are “pro-vaccination”, and “anti-vaccination” impacts the burden of measles. Using the projected cases and deaths, we calculated the health, healthcare, direct medical costs, and productivity loss associated with vaccine refusal. Using measles in England as a case study, we quantified the societal costs that each vaccine refusal imposes on society.FindingsWhen there is a high level of mixing between the pro- and anti-vaccination populations, those that refuse to be vaccinated benefit from the herd immunity afforded by the pro-vaccination population. At the same time, their refusal to be vaccinated increases the burden in those that are vaccinated due to imperfect vaccines, and in those that are not able to be vaccinated due to other underlying health conditions. Using England as a case study, we estimate that this translates to a societal loss of GBP 292 million and disease burden of 17 630 quality-adjusted-life-years (sensitivity range 10 594–50 379) over a 20-year time horizon. Of these costs, 26 % are attributable to healthcare costs and 74 % to productivity losses for patients and their carers. This translates to a societal loss per vaccine refusal of GBP 162.21 and 0.01 (0.006–0.03) quality-adjusted-life-years.InterpretationOur findings demonstrate that even low levels of vaccine refusal can have a substantial and measurable societal burden on the population. These estimates can support the value of investment in interventions that address vaccine hesitancy and vaccine refusal, providing not only improved public health but also potential economic benefits to society.     

The environmental burden of disease in Canada: respiratory disease, cardiovascular disease, cancer, and congenital affliction

BACKGROUND: Exposure to environmental hazards contributes to many chronic diseases, yet the magnitude of their contribution to the total disease burden in Canada is not well understood. OBJECTIVES: To estimate the environmental burden of disease (EBD) in Canada for respiratory disease, cardiovascular disease, cancer, and congenital affliction. Quantifying the contribution of environmental exposures to the overall burden of disease could play an important role in shaping public health and environmental policy priorities. METHODS: The World Health Organization (WHO) recently estimated the environmental burden of disease globally by using a combination of comparative risk assessment data and expert judgment to develop environmentally attributable fractions (EAFs) of mortality and morbidity for 85 categories of disease. We use the EAFs developed by the WHO, EAFs developed by other researchers, and data from Canadian public health institutions to provide an initial estimate of the environmental burden of disease in Canada for four major categories of disease. RESULTS: Our results indicate that: 10,000-25,000 deaths; 78,000-194,000 hospitalizations; 600,000-1.5 million days spent in hospital; 1.1 million-1.8 million restricted activity days for asthma sufferers; 8000-24,000 new cases of cancer; 500-2500 low birth weight babies; and between $3.6 billion and $9.1 billion in costs occur in Canada each year due to respiratory disease, cardiovascular illness, cancer, and congenital affliction associated with adverse environmental exposures. CONCLUSIONS: The burden of illness in Canada resulting from adverse environmental exposures is significant. Stronger efforts to prevent adverse environmental exposures are warranted, including research, education, and regulation.     

Safety of community drinking-water and outbreaks of waterborne enteric disease: Israel, 1976-97

Waterborne disease remains a major public health problem in many countries. We report findings on nearly three decades of waterborne disease in Israel and the part these diseases play in the total national burden of enteric disease. During the 1970s and 1980s, Israel's community water supplies were frequently of poor quality according to the microbiological standards at that time, and the country experienced many outbreaks of waterborne enteric disease. New regulations raised water quality standards and made chlorination of community water supplies mandatory, as well as imposing more stringent guidelines on maintaining water sources and distribution systems for both surface water and groundwater. This was followed by improved compliance and water quality, and a marked decline in the number of outbreaks of waterborne disease; no outbreaks were detected between 1992 and 1997. The incidence of waterborne salmonellosis, shigellosis, and typhoid declined markedly as proportions of the total burden of these diseases, but peaked during the time in which there were frequent outbreaks of waterborne disease (1980-85). Long-term trends in the total incidence of reported infectious enteric diseases from all sources, including typhoid, shigellosis, and viral hepatitis (all types) declined, while the total incidence of salmonellosis increased. Mandatory chlorination has had an important impact on improving water quality, in reducing outbreaks of waterborne disease in Israel, and reducing the total burden of enteric disease in the country.     

Alzheimer's disease: The strength of association of costs with different measures of disease severity

Objective

To identify Alzheimer's disease (AD) severity measures for use in cost-effectiveness models that effectively capture the impact of AD on costs.

Methods

A review of the literature and data abstraction from papers that present 1) mean AD costs (direct, indirect, or total) by disease severity, defined using measure of cognition, functional status, and behavior; and/or 2) the results of regression analyses that estimate the strength of the association between AD costs and disease severity.

Results

All papers reviewed showed that mean total costs increase with disease severity regardless of severity-measurement method. The relative difference in mean total costs between patients with severe disease compared to those with moderate disease, or moderate disease compared to mild disease, was fairly consistent across studies, suggesting that any of the disease-severity measures may be used to broadly categorize patients by cost. However, when regression analysis included multiple disease-severity measures, independent associations with costs were noted for the different measures. Cognitive and functional status measures were consistently associated with direct costs, whereas functional status and behavioral measures were consistently associated with indirect costs and caregiver hours.

Conclusions

Either multidimensional disease-severity measures, or a single disease-severity measure, that capture the impact of cognition, functional status, and behavior on costs are needed for cost-effectiveness models.     

Outbreaks of waterborne infectious intestinal disease in England and Wales, 1992-5.

Following the introduction of an improved surveillance system for infectious intestinal disease outbreaks in England and Wales, the Public Health Laboratory Service Communicable Disease Surveillance Centre received reports of 26 outbreaks between 1 January 1992 and 31 December 1995 in which there was evidence for waterborne transmission of infection. In these 26 outbreaks, 1756 laboratory confirmed cases were identified of whom 69 (4%) were admitted to hospital. In 19 outbreaks, illness was associated with the consumption of drinking water from public supplies (10 outbreaks) or private supplies (9 outbreaks). The largest outbreak consisted of 575 cases. In 4 of the remaining 7 outbreaks, illness was associated with exposure to swimming pool water. Cryptosporidium was identified as the probable causative organism in all 14 outbreaks associated with public water supplies and swimming pools. Campylobacter was responsible for most outbreaks associated with private water supplies. This review confirms a continuing risk of cryptosporidiosis from chlorinated water supplies in England and Wales, and reinforces governmental advice to water utilities that water treatment processes should be rigorously applied to ensure effective particle removal. High standards of surveillance are important for prompt recognition of outbreaks and institution of control measures. As microbiological evidence of water contamination may be absent or insufficient to implicate a particular water supply, a high standard of epidemiological investigation is recommended in all outbreaks of suspected waterborne disease.     

The socioeconomic costs of mental illness in Spain

Mental illness affects a large number of people in the world, seriously impairing their quality of life and resulting in high socioeconomic costs for health care systems and society. Our aim is to estimate the socioeconomic impact of mental illness in Spain for the year 2002, including health care resources, informal care and loss of labour productivity. A prevalence-based approach was used to estimate direct medical costs, direct non-medical costs, and loss of labour productivity. The total costs of mental illness have been estimated at 7,019 million euros. Direct medical costs represented 39.6% of the total costs and 7.3% of total public healthcare expenditure in Spain. Informal care costs represented 17.7% of the total costs. Loss of labour productivity accounted for 42.7% of total costs. In conclusion, the costs of mental illness in Spain make a considerable economic impact from a societal perspective.      

The study of infectious intestinal disease in England: socio-economic impact

To assess the socio-economic impact of infectious intestinal disease (IID) on the health care sector, cases and their families, cases of IID ascertained from a population cohort component and those presenting to general practices were sent a socio-economic questionnaire 3 weeks after the acute episode. The impact of the illness was measured and the resources used were identified and costed. The duration, severity and costs of illness linked to viruses were less than those linked to bacteria. The average cost per case of IID presenting to the GP was Pound Sterling253 and the costs of those not seeing a GP were Pound Sterling34. The average cost per case was Pound Sterling606 for a case with salmonella, Pound Sterling315 for campylobacter, Pound Sterling164 for rotavirus and Pound Sterling176 for SRSV. The estimated cost of IID in England was Pound Sterling743m expressed in 1994/5 prices. The costs of IID are considerable and the duration of the illness was found to be longer than previous reports have suggested.     

Observational epidemiologic studies of endemic waterborne risks: cohort, case-control, time-series, and ecologic studies

Observational studies have assessed endemic waterborne risks in a number of countries. Time-series analyses associated increased water turbidity with increased gastroenteritis risks in several public water systems. Several cohort studies reported an increased risk of gastroenteritis in populations using certain public or individual water systems. Although several case-control studies found increased waterborne risks, they also found increased risks associated with other exposures. An increased risk of campylobacteriosis was associated with drinking untreated water from non-urban areas and some tap waters; other significant risks included contaminated poultry and foreign travel. Increased risks of cryptosporidiosis and giardiasis were associated with drinking water in some populations; other risk factors included foreign travel, day care exposures, and swimming. These observational studies provide evidence that some populations may be at an increased risk of endemic or sporadic illness from waterborne exposures, but not all studies found an increased risk. Differences in waterborne risks may be due to differences in water quality. System vulnerabilities and contamination likely differed in the areas that were studied. The information from these studies may help inform estimates of waterborne illness for the US population but is inadequate to estimate a population attributable risk.     

Alcohol and burden of disease in Australia: the challenge in assessing consumption

Objective : Alcohol consumption is one of the major avoidable risk factors for disease, illness and injury in the Australian community. Population health scientists and economists use estimates of alcohol consumption in burden of disease frameworks to estimate the impact of alcohol on disease, illness and injury. This article highlights challenges associated with estimating alcohol consumption in these models and provides a series of recommendations to improve estimates. Methods : Key challenges in measuring alcohol consumption at the population level are identified and discussed with respect to how they apply to burden of disease frameworks. Results : Methodological advances and limitations in the estimation of alcohol consumption are presented with respect to use of survey data, population distributions of alcohol consumption, consideration of ‘patterns’ of alcohol use including ‘bingeing’, and capping exposure. Key recommendations for overcoming these limitations are provided. Implications and conclusion : Alcohol‐related burden has a significant impact on the health of the Australian population. Improving estimates of alcohol related consumption will enable more accurate estimates of this burden to be determined to inform future alcohol policy by legislators.     

A Markov model to estimate Salmonella morbidity, mortality, illness duration, and cost

Approximately 690000-1790000 Salmonella cases, 20000 hospitalizations, and 400 deaths occur in the USA annually, costing approximately $2.6bn. Existing models estimate morbidity, mortality, and cost solely from incidence. They do not estimate illness duration or use time as an independent cost predictor. Existing models may underestimate physician visits, hospitalizations, deaths, and associated costs. We developed a Markov chain Monte Carlo model to estimate illness duration, physician/emergency room visits, inpatient hospitalizations, mortality, and resultant costs for a given Salmonella incidence. Interested parties include society, third-party payers, health providers, federal, state and local governments, businesses, and individual patients and their families. The marginal approach estimates individual disease behavior for every patient, explicitly estimates disease duration and calculates separate time-dependent costs. The aggregate approach is a Markov equivalent of the existing models; it assumes average disease behavior and cost for a given morbidity/mortality. Transition probabilities were drawn from a meta-analysis of 53 Salmonella studies. Both approaches were tested using the 1993 Salmonella typhimurium outbreak in Gideon, Missouri. This protocol can be applied to estimate morbidity, mortality and cost of specific outbreaks, provide better national Salmonella burden estimates, and estimate the benefits of reducing Salmonella risk.     

Workshop summary: estimating waterborne disease risks in the United States

A workshop was held in Atlanta on July 7-8, 2005, to evaluate the epidemiologic and other information available for estimating endemic waterborne illness risks in the United States. Each paper written for this special issue was discussed and fourteen recommendations were made based on the discussion. In addition, seven major data gaps were identified as being key to reducing the uncertainty associated with a calculation of a national estimate. This summary is provided to help regulatory officials, public health professionals, and others better understand the health measures being estimated and adequacy of the current risk information. The summary also provides a blueprint for researchers interested in studying the endemic and epidemic risks of microbes in drinking water.     

The principles of disease elimination and eradication

The Dahlem Workshop discussed the hierarchy of possible public health interventions in dealing with infectious diseases, which were defined as control, elimination of disease, elimination of infections, eradication, and extinction. The indicators of eradicability were the availability of effective interventions and practical diagnostic tools and the essential need for humans in the life-cycle of the agent. Since health resources are limited, decisions have to be made as to whether their use for an elimination or eradication programme is preferable to their use elsewhere. The costs and benefits of global eradication programmes concern direct effects on morbidity and mortality and consequent effects on the health care system. The success of any disease eradication initiative depends strongly on the level of societal and political commitment, with a key role for the World Health Assembly. Eradication and ongoing programmes constitute potentially complementary approaches to public health. Elimination and eradication are the ultimate goals of public health, evolving naturally from disease control. The basic question is whether these goals are to be achieved in the present or some future generation.     

Quantifying the disease impact of alcohol with ARDI software.

Alcohol-Related Disease Impact (ARDI) Software has been developed for the Centers for Disease Control (CDC) to allow States to calculate mortality, years of potential life lost (YPLL), direct health-care costs, indirect morbidity and mortality costs, and nonhealth-sector costs associated with alcohol use and misuse. The mortality related measures--mortality, YPLL, and indirect mortality costs--are computed for 35 diagnoses related to alcohol use and misuse. A review of clinical research studies and injury surveillance studies was conducted to produce estimates of the alcohol-attributable fraction (AAF) for each diagnosis. For these measures, age-specific and age-adjusted rates are also calculated. Health care costs, morbidity costs, and nonhealth-sector costs are prorated from national studies to the State or locality. This multiple-measure approach to quantifying a health problem is termed "disease impact estimation." National estimates of the disease impact of alcohol use and misuse have been produced using ARDI software and State-specific estimates are in preparation. Designed to CDC specifications, ARDI is completely menu-driven and operates within Lotus 1-2-3 software as a set of linked spreadsheets. ARDI adapts national epidemiologic and health economics methods for use by State and local health agencies. ARDI produces data on the health consequences of alcohol use and misuse for use by locally based policymakers, public health professionals, and researchers, while permitting comparison and compilation of these data across jurisdictions.     

Cost-of-illness study of pneumococcal disease in Italian children

Streptococcus pneumoniae (S pneumoniae, or pneumococcus) is a leading cause of illness in children, and causes illness and death among the elderly and persons with certain underlying conditions. A Cost-of-Illness (COI) estimate for each pneumococcal disease (meningitis, bacteremia, pneumonia, and otitis media) was determined using decision tree analysis that considered both direct and indirect costs. Information on the burden of pneumococcal disease in Italy, in terms of data on the incidence and seroprevalence of disease was collected from published and unpublished records, supplemented, and verified by Italian pediatric and infectious disease experts. The annual cost to society of caring for children with pneumococcal disease is estimated to be around 59,604,477 euro including both direct costs and indirect costs (productivity changes). Direct costs accounted for 39.9% of the total costs. The value of resources used to treat otitis media was 60.6% of the total direct costs; 31.9% was the value of resources for treating pneumonia; 6.5% for treating bacteremia; 1.0% for treating meningitis. A sensitivity analysis confirmed the robustness of the results.     

Measuring the health burden of chronic disease and injury using health adjusted life expectancy and the Health Utilities Index

OBJECTIVES: To estimate the burden of illness from chronic disease and injury using a population based health survey, which contains both measures of chronic disease and a utility based health related quality of life (HRQOL) measure. DESIGN: An adapted Sullivan method was used to calculate cause deleted health adjusted life expectancies for chronic conditions. SETTING: Ontario, Canada, 1996/97. SUBJECTS: The 1996/97 Ontario Health Survey (n=35 527) was used to estimate the prevalence of chronic conditions. A cause deleted approach was used to estimate the impact of these conditions on the Health Utilities Index (HUI). Cause deleted probabilities of dying were derived with the cause eliminated life table technique and death data from vital statistics for Ontario 1996/97 (n=156 610). RESULTS: Eliminating cardiovascular disease and cancer will cause an "expansion of morbidity", while eliminating mental conditions and musculosketal disorders will result in a "contraction of morbidity". The HUI score varies depending on chronic condition, age, and sex-most of which were assumed not to vary in previous summary measures of population health. CONCLUSIONS: Health adjusted life expectancy estimated for chronic conditions using a utility based measure of health related quality of life from population health surveys addresses several limitations of previous studies that estimate the burden of disease using either a categorical measure of disability or expert opinion and related epidemiological evidence.     

An overview of methods for calculating the burden of disease due to specific risk factors

There are a number of measures that quantify the public health burden due to specific risk factors for specific diseases. Although these measures are of importance for policymakers, epidemiologists do not often calculate them or may be unfamiliar with some of the issues involved when they do. The primary measure of interest is the attributable fraction (AF), representing the fraction of cases or deaths from a specific disease that would not have occurred in the absence of exposure to a specific risk factor either in the exposed population or the population as a whole. AFs can be multiplied by the total number of cases of a given disease to obtain a "body count"--the absolute number of preventable cases due to a specific risk factor. Two other measures of public health burden, used in conjunction with AFs, are attributable years-of-life-lost and attributable disability-adjusted life-years. We provide an overview of the AF and related measures and discuss some of the specific issues involved in calculating AFs. These issues include calculating the variance of AFs (such as Monte Carlo sensitivity methods), biases arising from some formulas for the AF, sources of data for calculating AFs, dependence of AFs on basic decisions about what exposure-disease associations are causal, and extrapolation from the source population to the target population.