Foodborne Illness by the Millions: What’s Changed (and What Hasn’t)

Just how much foodborne illness is there? (too much) And are we making progress? (Questionable. Not enough). It’s challenging to compare numbers, but about every decade, a team of public health experts does it. So, here’s the new number, with a caveat: 10 million cases (9.9 million, but it seems reasonable to round up), but this is limited to the seven major foodborne pathogens.

The latest version was published in April 2025, with 2019 set as the year of the evaluation. Previous highly cited studies were published in 1999 (Mead et al., yielding 76 million cases of foodborne illness annually), followed by  2011 (Scallan et al., giving us 48 million cases/ 1 in 6 Americans). The 1999 and 2011 studies included estimates of foodborne illness due to unknown causes. So, no, the number of annual illnesses has NOT dropped dramatically. In 2011, Dr. Scallan, who is also the lead author of the present study, published another paper focused on the 31 significant pathogens that caused, at the time, an estimated 9.4 million cases of illness. This makes for a better comparison to the present work.

Norovirus is still the leading cause of illness, accounting for over half of the 10 million cases. This is immensely frustrating. The food supply chain puts so much work into keeping food safe, and then you have someone sick with norovirus who doesn’t wash their hands, generally right at the point of food preparation. The AFDO-led Healthy People 2030 initiative has a group focused on norovirus at retail and food service. It feels like it should be easy to bring these numbers down, but they’ve held disappointingly consistent over the decades.

The next largest contributor is Campylobacter, which causes an estimated 1.87 million cases/year. Campylobacter had generally been on par with Salmonella spp, but it has pulled ahead. Salmonella spp is “only” responsible for 1.28 million cases. We hear of Salmonella outbreaks, but we rarely hear of Campylobacter outbreaks. It is a peculiar organism, but we should pay more attention to it.

Organisms that cause more serious health outcomes, such as Shiga toxin-producing E. coli (O157 and non-O157) and Listeria monocytogenes, are associated with fewer illnesses but higher hospitalization rates (43% of cases of O157 are hospitalized, and over 87% of non-pregnancy-related cases of Listeriosis are hospitalized).

Each of the studies has estimated the amount of underdiagnosis and underreporting. We know many people don’t seek medical attention, and this is factored into the estimates. One change between the 2011 and the present study is the use of Culture Independent Diagnostics (CIDT)—not needing a bacterial culture (which takes time) for a doctor to diagnose illness. Most CIDTs test for 20+ gastrointestinal pathogens and have become standard in most urgent care and emergency department care models - providing a much greater likelihood that a human pathogen of concern might be identified. The authors also suggest that CIDTs may give us new insights into the true burden of foodborne illness.

How can we use these data? For food safety professionals, this means we can’t get complacent. We can’t slow down and probably need to work even harder to keep up as population demographics change, consumer preferences change, the global supply chain changes (due to weather, tariffs, or other factors), etc.

In addition to these reports, I monitor the Healthy People data, which examines per capita rates of foodborne illness (and many other health metrics) and sets targets for each decade. We are halfway between 2020 and 2030, and I hope our continued efforts will eventually result in progress.