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.
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.
In this data synthesis, Martyn Kirk and colleagues estimate the global and regional disease burden of 22 foodborne bacterial, protozoal and viral diseases.
Foodborne diseases are responsible for a large burden of illness (morbidity) and death (mortality) in both resource-rich and resource-poor countries. More than 200 diseases can be transmitted to people through the ingestion of food contaminated with microorganisms (bacteria, viruses, and parasites) or with chemicals. Contamination of food can occur at any stage of food production—on farms where crops are grown and animals raised, in factories where food is processed, and during food storage and preparation in shops, restaurants and the home. Contamination can arise because of pollution of the water, soil or air or through poor food-handling practices such as failing to wash one’s hands before preparing food. Many foodborne diseases (for example, norovirus, Escherichia coli, and campylobacter infections) present with gastrointestinal symptoms—stomach cramps, diarrhea, and vomiting. However, some foodborne illnesses cause symptoms affecting other parts of the body and some have serious sequelae (abnormal bodily conditions or diseases arising from a pre-existing disease). For example, infection with some strains of E. coli can lead to kidney failure.
Why Was This Study Done?
Accurate regional and global estimates of the disease burden of foodborne illnesses are needed to guide governmental and international efforts to improve food safety. However, estimates of the number of cases of foodborne illness, sequelae, deaths, and disability adjusted life years (a DALY represents the disease-related loss of one year of full health because of premature death or disability; DALYs provide a measure of the burden of a disease) are only available for a few countries. Consequently, in 2007, the World Health Organization (WHO) established the Foodborne Disease Burden Epidemiology Reference Group (FERG) to estimate the global and regional burden of disease attributable to foodborne illnesses. Here, researchers involved in one of the constituent task forces of FERG—the Enteric Diseases Task Force—undertake a data synthesis (the combination of information from many different sources) to provide global and regional estimates of the disease burden of several important foodborne bacterial, protozoal (parasitic), and viral diseases.
What Did the Researchers Do and Find?
The researchers combined national estimates of foodborne diseases and data from systematic reviews (studies that identify all the research on a given topic using predefined criteria), national surveillance programs, and other sources to estimate the number of illnesses, sequelae, deaths and DALYs globally and regionally for 22 diseases with sufficient data to support such estimations. Together, these 17 bacterial infections, two viral infections, and three protozoal infections caused 2 billion cases of illness, more than 1 million deaths, and almost 80 million DALYs in 2010. Using information on the proportions of infections considered to be foodborne by expert panels, the researchers estimated that nearly a third of these cases of illness (582 million cases), resulting in 25 million DALYs, were transmitted by contaminated food. Notably, 38% of the cases of foodborne illness, 33% of deaths from these diseases, and 43% of the disease burden from contaminated food (11 million DALYs) occurred in children under 5 years old. The leading cause of foodborne illness was norovirus (125 million cases), closely followed by campylobacter (96 million); diarrheal and invasive infections caused by non-typhoidal Salmonella enterica infections caused the largest burden of disease (4.07 million DALYs). Finally, the burden of foodborne illness was highest in WHO’s African region.
What Do These Findings Mean?
The lack of reliable data on the 22 illnesses considered in this analysis for many regions of the world, including some of the most populous regions, and uncertainty about the proportion of the cases of each illness that is foodborne may limit the accuracy of these findings. Nevertheless, these results provide new information about the regional and global disease burden caused by foodborne illnesses. In particular, these estimates reveal an unexpectedly high disease burden caused by foodborne illnesses among young children. Thus, although children under the age of 5 years represent only 9% of the global population, nearly half of the disease burden from contaminated food may occur in this age group. Overall, the findings of this study suggest that governments and international agencies should prioritize food safety to prevent foodborne illness, particularly among young children, and highlight the need to identify effective food hygiene interventions that can be implemented in low- and middle-income countries.
This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001921.
The World Health Organization provides information about foodborne diseases, food safety and the estimation of the global burden of foodborne diseases (available in several languages)
The US National Institute of Allergy and Infectious Diseases provides detailed information about several foodborne illnesses
The US Centers for Disease Control and Prevention provides information about foodborne disease outbreaks in the US and elsewhere and information about food safety in the US
The UK National Health Service Choices website provides information about food poisoning (another name for foodborne illness) and about food safety
STOP Foodborne Illness STOP Foodborne Illness, a US non-profit public-health organization, provides personal stories about foodborne illness