Martyn Kirk

World Health Organization Estimates of the Global and Regional Disease Burden of 22 Foodborne Bacterial, Protozoal, and Viral Diseases, 2010: A Data Synthesis

Background Foodborne diseases are important worldwide, resulting in considerable morbidity and mortality. To our knowledge, we present the first global and regional estimates of the disease burden of the most important foodborne bacterial, protozoal, and viral diseases. Methods and Findings We synthesized data on the number of foodborne illnesses, sequelae, deaths, and Disability Adjusted Life Years (DALYs), for all diseases with sufficient data to support global and regional estimates, by age and region. The data sources included varied by pathogen and included systematic reviews, cohort studies, surveillance studies and other burden of disease assessments. We sought relevant data circa 2010, and included sources from 1990–2012. The number of studies per pathogen ranged from as few as 5 studies for bacterial intoxications through to 494 studies for diarrheal pathogens. To estimate mortality for Mycobacterium bovis infections and morbidity and mortality for invasive non-typhoidal Salmonella enterica infections, we excluded cases attributed to HIV infection. We excluded stillbirths in our estimates. We estimate that the 22 diseases included in our study resulted in two billion (95% uncertainty interval [UI] 1.5–2.9 billion) cases, over one million (95% UI 0.89–1.4 million) deaths, and 78.7 million (95% UI 65.0–97.7 million) DALYs in 2010. To estimate the burden due to contaminated food, we then applied proportions of infections that were estimated to be foodborne from a global expert elicitation. Waterborne transmission of disease was not included. We estimate that 29% (95% UI 23–36%) of cases caused by diseases in our study, or 582 million (95% UI 401–922 million), were transmitted by contaminated food, resulting in 25.2 million (95% UI 17.5–37.0 million) DALYs. Norovirus was the leading cause of foodborne illness causing 125 million (95% UI 70–251 million) cases, while Campylobacter spp. caused 96 million (95% UI 52–177 million) foodborne illnesses. Of all foodborne diseases, diarrheal and invasive infections due to non-typhoidal S. enterica infections resulted in the highest burden, causing 4.07 million (95% UI 2.49–6.27 million) DALYs. Regionally, DALYs per 100,000 population were highest in the African region followed by the South East Asian region. Considerable burden of foodborne disease is borne by children less than five years of age. Major limitations of our study include data gaps, particularly in middle- and high-mortality countries, and uncertainty around the proportion of diseases that were foodborne. Conclusions Foodborne diseases result in a large disease burden, particularly in children. Although it is known that diarrheal diseases are a major burden in children, we have demonstrated for the first time the importance of contaminated food as a cause. There is a need to focus food safety interventions on preventing foodborne diseases, particularly in low- and middle-income settings.

World Health Organization Global Estimates and Regional Comparisons of the Burden of Foodborne Disease in 2010

Illness and death from diseases caused by contaminated food are a constant threat to public health and a significant impediment to socio-economic development worldwide. To measure the global and regional burden of foodborne disease (FBD), the World Health Organization (WHO) established the Foodborne Disease Burden Epidemiology Reference Group (FERG), which here reports their first estimates of the incidence, mortality, and disease burden due to 31 foodborne hazards. We find that the global burden of FBD is comparable to those of the major infectious diseases, HIV/AIDS, malaria and tuberculosis. The most frequent causes of foodborne illness were diarrheal disease agents, particularly norovirus and Campylobacter spp. Diarrheal disease agents, especially non-typhoidal Salmonella enterica, were also responsible for the majority of deaths due to FBD. Other major causes of FBD deaths were Salmonella Typhi, Taenia solium and hepatitis A virus. The global burden of FBD caused by the 31 hazards in 2010 was 33 million Disability Adjusted Life Years (DALYs); children under five years old bore 40% of this burden. The 14 subregions, defined on the basis of child and adult mortality, had considerably different burdens of FBD, with the greatest falling on the subregions in Africa, followed by the subregions in South-East Asia and the Eastern Mediterranean D subregion. Some hazards, such as non-typhoidal S. enterica, were important causes of FBD in all regions of the world, whereas others, such as certain parasitic helminths, were highly localised. Thus, the burden of FBD is borne particularly by children under five years old–although they represent only 9% of the global population–and people living in low-income regions of the world. These estimates are conservative, i.e., underestimates rather than overestimates; further studies are needed to address the data gaps and limitations of the study. Nevertheless, all stakeholders can contribute to improvements in food safety throughout the food chain by incorporating these estimates into policy development at national and international levels.

Estimating the Burden of Acute Gastroenteritis, Foodborne Disease, and Pathogens Commonly Transmitted by Food: An International Review

The burden of foodborne disease is not well defined in many countries or regions or on a global level. The World Health Organization (WHO), in conjunction with other national public health agencies, is coordinating a number of international activities designed to assist countries in the strengthening of disease surveillance and to determine the burden of acute gastroenteritis. These data can then be used to estimate the following situations: (1) the burden associated with acute gastroenteritis of foodborne origin, (2) the burden caused by specific pathogens commonly transmitted by food, and (3) the burden caused by specific foods or food groups. Many of the scientists collaborating with the WHO on these activities have been involved in quantifying the burden of acute gastroenteritis on a national basis. This article reviews these key national studies and the international efforts that are providing the necessary information and technical resources to derive national, regional, and global burden of disease estimates.

Estimating Foodborne Gastroenteritis, Australia

An estimated 4.0–6.9 million episodes of foodborne gastroenteritis occur in Australia each year.

Health effects of exposure to cyanobacteria (blue–green algae) during recreational water–related activities

Abstract: The aim of this study was to investigate effects on health of exposure to cyanobacteria as a result of recreational water activities. Participants, who were aged six years and over, were interviewed at water recreation sites in South Australia, New South Wales and Victoria on selected Sundays during January and February 1995. Telephone follow–up was conducted two and seven days later to record any subsequent diarrhoea, vomiting, flu–like symptoms, skin rashes, mouth ulcers, fevers and eye or ear irritations. On the Sundays of interview, water samples from the sites were collected for cyanobac–terial cell counts and toxin analysis. There were 852 participants, of whom 75 did not have water contact on the day of interview and were considered unexposed. The 777 who had water contact were considered exposed. No significant differences in overall symptoms were found between the unexposed and exposed after two days. At seven days, there was a significant trend to increasing symptom occurrence with duration of exposure (P = 0.03). There was a significant trend to increasing symptom occurrence with increase in cell count (P = 0.04). Participants exposed to more than 5000 cells per mL for more than one hour had a significantly higher symptom occurrence rate than the unexposed. Symptoms were not correlated with the presence of hepatotoxins. These results suggest symptom occurrence was associated with duration of contact with water containing cyanobacteria, and with cyanobacterial cell density. The findings suggest that the current safety threshold for exposure of 20 000 cells per mL may be too high. (Aust N Z J Public Health 1997; 21: 562–6)

The global burden of listeriosis: a systematic review and meta-analysis

BACKGROUND Listeriosis, caused by Listeria monocytogenes, is an important foodborne disease that can be difficult to control and commonly results in severe clinical outcomes. We aimed to provide the first estimates of global numbers of illnesses, deaths, and disability-adjusted life-years (DALYs) due to listeriosis, by synthesising information and knowledge through a systematic review. METHODS We retrieved data on listeriosis through a systematic review of peer-reviewed and grey literature (published in 1990-2012). We excluded incidence data from before 1990 from the analysis. We reviewed national surveillance data where available. We did a multilevel meta-analysis to impute missing country-specific listeriosis incidence rates. We used a meta-regression to calculate the proportions of health states, and a Monte Carlo simulation to generate DALYs by WHO subregion. FINDINGS We screened 11,722 references and identified 87 eligible studies containing listeriosis data for inclusion in the meta-analyses. We estimated that, in 2010, listeriosis resulted in 23,150 illnesses (95% credible interval 6061-91,247), 5463 deaths (1401-21,497), and 172,823 DALYs (44,079-676,465). The proportion of perinatal cases was 20·7% (SD 1·7). INTERPRETATION Our quantification of the global burden of listeriosis will enable international prioritisation exercises. The number of DALYs due to listeriosis was lower than those due to congenital toxoplasmosis but accords with those due to echinococcosis. Urgent efforts are needed to fill the missing data in developing countries. We were unable to identify incidence data for the AFRO, EMRO, and SEARO WHO regions. FUNDING WHO Foodborne Diseases Epidemiology Reference Group and the Université catholique de Louvain.

World Health Organization Estimates of the Global and Regional Disease Burden of 11 Foodborne Parasitic Diseases, 2010: A Data Synthesis.

Background Foodborne diseases are globally important, resulting in considerable morbidity and mortality. Parasitic diseases often result in high burdens of disease in low and middle income countries and are frequently transmitted to humans via contaminated food. This study presents the first estimates of the global and regional human disease burden of 10 helminth diseases and toxoplasmosis that may be attributed to contaminated food. Methods and Findings Data were abstracted from 16 systematic reviews or similar studies published between 2010 and 2015; from 5 disease data bases accessed in 2015; and from 79 reports, 73 of which have been published since 2000, 4 published between 1995 and 2000 and 2 published in 1986 and 1981. These included reports from national surveillance systems, journal articles, and national estimates of foodborne diseases. These data were used to estimate the number of infections, sequelae, deaths, and Disability Adjusted Life Years (DALYs), by age and region for 2010. These parasitic diseases, resulted in 48.4 million cases (95% Uncertainty intervals [UI] of 43.4–79.0 million) and 59,724 (95% UI 48,017–83,616) deaths annually resulting in 8.78 million (95% UI 7.62–12.51 million) DALYs. We estimated that 48% (95% UI 38%-56%) of cases of these parasitic diseases were foodborne, resulting in 76% (95% UI 65%-81%) of the DALYs attributable to these diseases. Overall, foodborne parasitic disease, excluding enteric protozoa, caused an estimated 23.2 million (95% UI 18.2–38.1 million) cases and 45,927 (95% UI 34,763–59,933) deaths annually resulting in an estimated 6.64 million (95% UI 5.61–8.41 million) DALYs. Foodborne Ascaris infection (12.3 million cases, 95% UI 8.29–22.0 million) and foodborne toxoplasmosis (10.3 million cases, 95% UI 7.40–14.9 million) were the most common foodborne parasitic diseases. Human cysticercosis with 2.78 million DALYs (95% UI 2.14–3.61 million), foodborne trematodosis with 2.02 million DALYs (95% UI 1.65–2.48 million) and foodborne toxoplasmosis with 825,000 DALYs (95% UI 561,000–1.26 million) resulted in the highest burdens in terms of DALYs, mainly due to years lived with disability. Foodborne enteric protozoa, reported elsewhere, resulted in an additional 67.2 million illnesses or 492,000 DALYs. Major limitations of our study include often substantial data gaps that had to be filled by imputation and suffer from the uncertainties that surround such models. Due to resource limitations it was also not possible to consider all potentially foodborne parasites (for example Trypanosoma cruzi). Conclusions Parasites are frequently transmitted to humans through contaminated food. These estimates represent an important step forward in understanding the impact of foodborne diseases globally and regionally. The disease burden due to most foodborne parasites is highly focal and results in significant morbidity and mortality among vulnerable populations.

Case-control studies of sporadic cryptosporidiosis in Melbourne and Adelaide, Australia.

Few studies have assessed risk factors for sporadic cryptosporidiosis in industrialized countries, even though it may be numerically more common than outbreaks of disease. We carried out case-control studies assessing risk factors for sporadic disease in Melbourne and Adelaide, which have water supplies from different ends of the raw water spectrum. In addition to examining drinking water, we assessed several other exposures. 201 cases and 795 controls were recruited for Melbourne and 134 cases and 536 controls were recruited for Adelaide. Risk factors were similar for the two cities, with swimming in public pools and contact with a person with diarrhoea being most important. The consumption of plain tap water was not found to be associated with disease. This study emphasizes the need for regular public health messages to the public and swimming pool managers in an attempt to prevent sporadic cryptosporidiosis, as well as outbreaks of disease.

Internationally Distributed Frozen Oyster Meat Causing Multiple Outbreaks of Norovirus Infection in Australia

BACKGROUND Between November 2003 and January 2004, outbreaks of norovirus in 3 Australian jurisdictions involving 83 cases of illness were associated with imported oyster meat. METHODS Cohort studies were conducted in 2 jurisdictions to identify relative risks of illness for the consumption of oysters. A case series was conducted in the third jurisdiction. RESULTS The cohort studies conducted in the first 2 jurisdictions identified relative risks of illness of 17 (95% confidence interval, 5-51) and 35 (95% confidence interval, 5-243), respectively, for the consumption of oysters. Multiple strains of norovirus were detected in fecal specimens from 8 of 14 patients and in 1 of the 3 batches of implicated oyster meat using seminested reverse-transcriptase polymerase chain reaction methods. Traceback investigations revealed that all oyster meat was harvested from the same estuary system in Japan within the same month. CONCLUSIONS These outbreaks demonstrate the potential of foodborne disease to spread internationally and the need for national and international collaboration to investigate such outbreaks. Foodborne illness related to norovirus is underestimated because of underreporting of human cases and challenges in laboratory detection of viruses in foods, both of which can delay public health action.

Global Incidence of Human Shiga Toxin–Producing Escherichia coli Infections and Deaths: A Systematic Review and Knowledge Synthesis

OBJECTIVES Shiga toxin-producing Escherichia coli (STEC) are an important cause of foodborne disease, yet global estimates of disease burden do not exist. Our objective was to estimate the global annual number of illnesses due to pathogenic STEC, and resultant hemolytic uremic syndrome (HUS), end-stage renal disease (ESRD), and death. MATERIALS We searched Medline, Scopus, SIGLE/OpenGrey, and CABI and World Health Organization (WHO) databases for studies of STEC incidence in the general population, published between January 1, 1990 and April 30, 2012, in all languages. We searched health institution websites for notifiable disease data and reports, cross-referenced citations, and consulted international knowledge experts. We employed an a priori hierarchical study selection process and synthesized results using a stochastic simulation model to account for uncertainty inherent in the data. RESULTS We identified 16 articles and databases from 21 countries, from 10 of the 14 WHO Sub-Regions. We estimated that STEC causes 2,801,000 acute illnesses annually (95% Credible Interval [Cr.I.]: 1,710,000; 5,227,000), and leads to 3890 cases of HUS (95% Cr.I.: 2400; 6700), 270 cases of ESRD (95% Cr.I.: 20; 800), and 230 deaths (95% Cr.I.: 130; 420). Sensitivity analyses indicated these estimates are likely conservative. CONCLUSIONS These are the first estimates of the global incidence of STEC-related illnesses, which have not been explicitly included in previous global burden of disease estimations. Compared to other pathogens with a foodborne transmission component, STEC appears to cause more cases than alveolar echinococcosis each year, but less than typhoid fever, foodborne trematodes, and nontyphoidal salmonellosis. APPLICATIONS Given the persistence of STEC globally, efforts aimed at reducing the burden of foodborne disease should consider the relative contribution of STEC in the target population.