The World Health Organization (WHO) estimates that 33 million years of healthy lives are lost globally each year because of eating unsafe food, and this number is likely an underestimation. See WHO's Estimating the Burden of Foodborne Diseases.
For the global estimates, WHO assessments include 31 foodborne hazards causing 32 diseases: 11 diarrheal disease agents (1 virus, 7 bacteria, 3 protozoa), 7 invasive infectious disease agents (1 virus, 5 bacteria, 1 protozoon), 10 helminths, and 3 chemicals. Together, the 31 global hazards caused approximately 600 million foodborne illnesses and 420,000 deaths in 2010. The most frequent causes of foodborne illness were diarrheal disease agents, particularly norovirus and Campylobacter spp. Foodborne diarrheal disease agents—particularly nontyphoidal Salmonella enterica (NTS)—caused approximately 230,000 deaths. Other major causes of foodborne deaths were Salmonella Typhi, Taenia solium, hepatitis A virus, and aflatoxin. The global burden of foodborne disease by these 31 hazards was 33 million disability-adjusted life years (DALYs) in 2010; 40% of the foodborne disease burden was among children under 5 years old. Worldwide, 18 million DALYs were attributed to foodborne diarrheal disease agents, particularly NTS and enteropathogenic Escherichia coli.
In the US, foodborne diseases are not generally reportable, so their burden likely is grossly underestimated. Contributing to this underestimation is that many foodborne illnesses lack the severity, duration, and specific diagnosis required for definitive identification and intervention. The CDC estimates that foodborne pathogens cause approximately 48 million illnesses, 128,000 hospitalizations, and 3,000 deaths each year in the US. (See CDC's Foodborne Germs and Illnesses.)
In an effort to maintain awareness of foodborne disease events and trends, CDC conducts the Foodborne Diseases Active Surveillance Network (FoodNet), which monitors the incidence of nine foodborne pathogens in ten US cities, covering approximately 15% of the American population. See, for example, Preliminary Incidence and Trends of Infections with Pathogens Transmitted Commonly Through Food—Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2015–2018.
Trends in Foodborne Illness in Epidemiology
In 2019, compared with the previous 3 years, the incidence of infections caused by pathogens transmitted commonly through food increased (for Campylobacter, Cyclospora, Shiga toxin–producing E coli [STEC], Vibrio, Yersinia) or remained unchanged (for Listeria, Salmonella, Shigella). These data indicate that Healthy People 2020 targets for reducing foodborne illness will not be met. Better implementation of known prevention approaches and new strategies is needed to overcome the continued challenges to reducing foodborne illnesses.
Pathogenic organisms that contaminate food and result in foodborne illness are dynamic in that they adapt to new foods, processes, and human behaviors. The following categorical factors contribute to foodborne illness trends.
Human Demographics and Behavior
The proportion of the US population that is immunocompromised is increasing because of factors such as advancing age, underlying disease, and therapeutic drug regimens. In addition, humans consume more fresh fruits and vegetables, which may be more contaminated than processed or prepared foods, and they consume an increasing number of meals outside the home. Foods with minimal processing have not necessarily been shown to be microbiologically safer and in some cases may even increase the risk from certain foodborne pathogens (eg, raw milk).
Technologies Within the Food Industry
Increasing concentration and vertical integration of many food production sectors have resulted in foods of higher quality and greater consistency but with certain inherent vulnerabilities. Foods (and constituent ingredients) are transported in larger batches, over longer distances, and are processed into an increasing number of end products. Therefore, refrigeration breakdowns and cross-contamination incidents can result in more widespread effects of food recalls and illness outbreaks.
International Travel and Commerce
Increasingly, bulk food shipments cross international borders, allowing humans to contract foodborne illnesses acquired from foreign foods. In addition, when people travel, they frequently take cultural foods with them to share with extended family. Despite prohibitions against such importation practices, ~1.8 metric tonnes of meat products are confiscated each month from people traveling from Haiti to the US. Undoubtedly, this represents only a fraction of the amount actually crossing the border.
New and emerging bacteria, toxins, and antimicrobial resistance present food safety challenges. Foodborne pathogens have inexorably adapted to traditional preservation techniques. Others may even be selected for by various techniques. Finally, antimicrobial resistance patterns change constantly, requiring correspondingly dynamic interventions.
Economic Development and Land Use
USDA reports a continuing decrease in the number of farms in the US, with the number of production animals on remaining farms increasing. Such consolidation concentrates the number of animals that may be affected, both by infectious pathogens and by interventions such as quarantines and depopulation efforts. Increases in ocean water temperature have been associated with increases in the number and scope of foodborne illnesses from certain seafood products, such as oysters.