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Incidence and Impact of Foodborne Diseases

By Donald L. Noah, DVM, MPH, DACVPM, Midwestern University ; Stephanie R. Ostrowski, DVM, MPVM, DACVPM, Department of Pathobiology, College of Veterinary Medicine, Auburn University

The global burden of foodborne diseases is difficult to assess, because no overarching estimation has yet been performed. The World Health Organization has initiated this process but reports that efforts are limited by regional lack of funding, public health infrastructure, and political will. However, despite specific data, the burden seems obvious; diarrheal diseases, many of which are foodborne in origin, kill approximately 1.9 million children worldwide.

In the USA, the foodborne diseases are not generally reportable, so their burden likely is significantly underestimated. Contributing to this underestimation is that many foodborne illnesses lack the severity, duration, and specific diagnosis required for definitive identification and intervention. Recent estimates by the CDC indicate that foodborne pathogens cause approximately 9.6 million illnesses, 57,500 hospitalizations, and 1,500 deaths each year in the USA.

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 USA cities, covering approximately 15% of the American population (see Table: Foodborne Pathogens in Ten USA Cities).

Foodborne Pathogens in Ten USA Cities

Pathogen

Incidence of Illness per 100,000 Population

Salmonella

15.19

Campylobacter

13.82

Shigella

4.82

Cryptosporidium

2.48

Shigatoxin-producing E coli

2.32

Vibrio

0.51

Yersinia

0.36

Listeria

0.26

Cyclospora

0.03

CDC reports that this epidemiologic situation has not changed appreciably since 2006, suggesting that there are gaps in the current food safety system and a need for better, more effective interventions.

Factors in Emerging Foodborne Illness Trends

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 USA population that is immunocompromised is increasing because of factors such as advancing age, underlying disease, and therapeutic drug regimens. Additionally, people consume more fresh fruits and vegetables, which may be more contaminated than processed or prepared foods, and consume an increasing number of meals outside the home. Finally, “organic” foods have not been shown to be microbiologically safer and in some cases may even increase the risk from certain foodborne pathogens.

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 batch sizes, over longer distances, and are processed into an increasing number of end products. This means that refrigeration breakdowns and cross-contamination incidents can result in more widespread effects of food recalls and illness outbreaks.

International Travel and Commerce:

The concept of “traveler’s diarrhea” is expanding because, increasingly, bulk food shipments cross international borders at least as often as people. Therefore, foodborne illnesses acquired from foreign foods can be contracted without leaving home. Additionally, when people travel, they frequently take cultural foods with them to share with extended family. Despite prohibitions against such importation practices, ~4,000 pounds of meat products are confiscated from travelers each month from Haiti to the USA. Undoubtedly, this represents only a fraction of the amount actually crossing the border.

Microbial Adaptation:

Foodborne pathogens have inexorably adapted to traditional preservation techniques. Others may even be selected 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 USA, with the average number of livestock animals on remaining farms increasing. This concentrates the number of animals that may be affected, both by contagious 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.

Lack of Food Safety Education:

Health classes at the intermediate and high school levels rarely, if ever, cover food safety in favor of topics such as sexually transmitted diseases, drug abuse, and teen pregnancy. With the increasing fraction of two-worker and single-parent homes, time demands may also preclude education of children in food safety principles and further contribute to the lack of awareness.

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