ATLANTA – Progress toward controlling certain foodborne pathogens has stalled, the Centers for Disease Control and Prevention (CDC) said in a recent Morbidity and Mortality Weekly Report (MMWR).

A review of Foodborne Diseases Active Surveillance Network (FoodNet) data for 2019 found that, compared with the previous three years, the incidence of infections caused by foodborne pathogens increased for Campylobacter, Cyclospora, STEC, Vibrio, Yersinia, while incidence of infections was unchanged for Listeria, Salmonella and Shigella.

FoodNet identified 25,866 cases of infection, 6,164 hospitalizations, and 122 deaths in 2019. The overall incidence per 100,000 population was highest for Campylobacter (19.5), followed by Salmonella (17.1), STEC (6.3), Shigella (4.8), Cyclospora (1.5), Yersinia (1.4), Vibrio (0.9), and Listeria (0.3).

“Serotype Enteritidis has been the most common cause of Salmonella infections at FoodNet sites since 2007 and incidence has not decreased,” the report said. “Eggs were the major source of Enteritidis infections in the 1980s. Chicken was recognized as another important source during the late 1990s.

“Infantis moved from the ninth most common Salmonella serotype among infected persons during 1996–1998 to the sixth most common in 2019. Many infections are now caused by a new, highly resistant strain found in chicken.”

The CDC noted that laboratory diagnosed non-O157 STEC infections continue to increase, although STEC O157 infections appear to be decreasing. Outbreaks have been linked to leafy greens. Produce also is a significant source for Cyclospora, Listeria, and Salmonella, the report said.

However, the incidence of some Salmonella serotypes has declined. Typhimurium moved from the most common serotype during 1996–1998 to the third most common in 2019, and Salmonella Heidelberg is no longer among the top 20.

“These decreases might be partly related to the widespread practice of vaccinating chickens against Typhimurium, which shares antigens with Heidelberg,” the CDC said. “This observation, combined with a marked decline in Enteritidis infections in the United Kingdom after implementation of widespread chicken vaccination and improved farm hygiene, suggests that targeting other serotypes through poultry vaccination could be one way to reduce human illnesses in the United States.”

Furthermore, the data shows that the United States will not meet foodborne illness reduction targets established 10 years ago with the launch of Healthy People 2020, which is a national agenda of the US Department of Health and Human Services aimed at improving public health and preventing disease.

Food safety objectives HHS had hoped to achieve by 2020 include:

  • increasing the proportion of consumers who follow key food safety practices;
  • reducing the number of outbreak-associated infections due to Shiga toxin-producing E. coli O157, or Campylobacter, Listeria, or Salmonella associated with food commodity groups; and
  • increasing the proportion of fast-food and full-service restaurants that follow food safety practices that prevent foodborne illness outbreaks, among other goals.

“The landscape of foodborne disease continues to change, as do the methods to determine the incidence and sources of these infections,” the CDC said. “FoodNet surveillance data indicate that progress in controlling major foodborne pathogens in the United States has stalled.

“To better protect the public and achieve forthcoming Healthy People 2030 foodborne disease reduction goals, more widespread implementation of known prevention measures and new strategies that target particular pathogens and serotypes are needed.”

The CDC noted that the increase in incidence is likely due to increased use of tests that identify previously unrecognized infections along with changes in ordering practices and varying test sensitivities and specificities might also contribute to the increase in incidence.

Also, access to health services and individuals seeking care may have changed. Finally, year-to-year changes in incidence might not reflect sustained trends.