Effective efforts to prevent foodborne illnesses require expanded and improved collaboration throughout the food safety system to ensure that emerging pathogens can be spotted and addressed as early as possible. Increased coordination among industry and public sector stakeholders, along with dissemination of identifying information and other surveillance data that can provide critical warnings, is crucial to enhancing the United States’ response to new or growing food safety risks.
Without such steps, Americans’ food supply will remain unacceptably vulnerable to contamination by new strains of bacteria and other pathogens.
The recent spread of the Salmonella Infantis strain across the nation illustrates the need for broad coordination among key stakeholders and highlights the importance of reducing foodborne illness to protect the public’s health. Historically, the Infantis serotype has caused a small proportion of the estimated 1 million foodborne Salmonella infections in the U.S. each year. Over the last decade, however, the rate of human infections caused by this strain increased by about 50%.
At the same time, food producers and regulators have struggled to mobilize effective defenses against Infantis, despite the warning signs. In 2011, for example, a World Health Organization study presented evidence that illnesses from this strain of Salmonella were increasing in developed countries around the globe. The authors noted that nations may have to “develop and implement novel control strategies” for such emerging strains because food safety interventions for certain Salmonella serotypes do not work for others.
A report by the Centers for Disease Control and Prevention echoed the WHO concerns in the U.S., finding that the nation’s foodborne infection rate for Salmonella Infantis rose significantly in 2014 compared with the 2006-08 average.
Also in 2014, a federal program that monitors bacterial resistance to antibiotics detected a multidrug-resistant strain of Infantis in retail chicken products. Researchers later realized that the same strain had caused a foodborne infection in 2012, and that strain was similar to one causing illnesses and poultry contamination in other countries. But food safety officials did not connect the signals until later, possibly because federal agencies did not begin to routinely analyze and compare the DNA of bacterial samples from different surveillance systems until 2014.
Without access to on-farm or production-level surveillance tools that could identify and correlate emerging strains, researchers could not determine exactly when or how the multidrug-resistant Infantis strain was introduced into poultry stock in the U.S. Still, their work suggested that shipments of infected breeder stock and contaminated agricultural products such as chicken feed could quickly spread pathogens around the world.
Pathogens can quickly proliferate throughout the food supply, and bacteria can infect many people before surveillance data indicates that they have become a widespread problem. Experts estimate that for every confirmed Salmonella infection, there may be 29 illnesses that surveillance systems do not capture. This means that Salmonella Infantis was likely already spreading widely in the U.S. in 2014 and more people became sick from consuming food contaminated with the bacterium than surveillance data had revealed.
By 2018, the drug-resistant Salmonella strain had spread throughout the U.S. chicken supply, causing a major outbreak that sickened people in 32 states. At least 129 people were infected between January 2018 and February 2019; one person died.
Federal investigators linked the illnesses to various chicken products from multiple companies. Samples taken from live birds and 76 slaughter and processing facilities tested positive for the outbreak strain, leading CDC to report that the pathogen was likely widespread in the nation’s poultry industry.
The emergence of Salmonella Infantis, its broad spread among domestic chicken producers, and the multistate outbreak linked to chicken demonstrate the importance of improved coordination and data-sharing to identify emerging foodborne pathogens. Effective approaches would build on existing stakeholder collaboration and data-sharing efforts and expand communication networks that include industry, regulators, and consumer and public health groups.
A more robust data-coordination model would integrate evidence from multiple surveillance systems. This could include international networks and producer data that could provide early warnings of new potential threats. Policymakers also should support expanding the animal protein industry’s capacity to develop more efficient methods for alerting growers and operators, food safety regulators, and public health officials when new serotypes appear in herds or flocks.
The next emerging threat, whether from Salmonella or another bacterium, is likely just around the corner. The nation needs to be better prepared for these events to ensure that authorities and food companies can act quickly to keep consumers safe.
Sandra Eskin directs The Pew Charitable Trusts’ work on food safety.