One Step Ahead: Investigating Salmonella in the United States

In order to control and prevent outbreaks of Salmonella, public health scientists and officials work tirelessly to ensure the farm to table chain remains free of contamination. They employ a variety of methods, technologies, and collaborations to remain one step ahead.

Most recently, the Center for Disease Control and Prevention (CDC) collaborated with public health officials in several states, along with, the US Food and Drug Administration (FDA) to investigate a multi-state outbreak of Salmonella Reading and Salmonella Abony infections. In order to identify illnesses that may be part of this outbreak, public health investigators utilized the PulseNet System.

“PulseNet compares the DNA fingerprints of bacteria from patients to find clusters of disease that might represent unrecognized outbreaks,” according to the CDC. Laboratorians throughout the United States submit samples to the CDC; when there is a match an investigation can be launched to detect the source.

According to officials at the CDC, “Thirty people infected with the [multi-state] outbreak strains have been reported from nine states. Of those ill people, 24 were infected with Salmonella Reading, 1 was infected with Salmonella Abony, and 5 were infected with both. A list of the states and the number of cases in each can be found on the Case Count Map page.” The investigation continues and the CDC plans to update their website as more information becomes available.

Salmonella, it is estimated, causes one million food-borne illnesses, 19,000 hospitalizations, and 380 deaths annually, in the United States. Public health scientists have been tracing Salmonella infections since 1962. Identifying structures on the bacteria’s surface, have allowed scientists to classify the many types of Salmonella into serotypes.

In 2013, the CDC released a first-of-its-kind report, available for download. It charts over 40 years of laboratory-confirmed surveillance data on 32 Salmonella serotypes. An Atlas of Salmonella in the United States, 1968-2011 includes analysis by age, sex, season, and geography down to the county level. The goal is to help users understand Salmonella and trends in order to develop more informed solutions to reduce contamination.

Along-side tracking and surveillance, the CDC's Outbreak Response and Prevention Branch (ORPB) “collaborates with epidemiologists and other public health officials who investigate clusters of food-borne, waterborne, zoonotic, and other enteric (gastrointestinal) illnesses in the United States.”

The CDC’s ORPB “works to ensure rapid and coordinated surveillance, detection, and response to multistate outbreaks caused by enteric bacteria, including Salmonella and Escherichia coli infections.

Salmonella, Shiga-toxin producing Escherichia coli (STEC, including O157 and other serogroups), Listeria, Shigella, Vibrio, and hepatitis A virus, as well as botulism are reportable almost anywhere in the United States through the National Notifiable Diseases Surveillance System (NNDS). The system tracks contagious diseases that laboratory professionals and doctors report to the state or territorial public health agency. In most cases health care professionals should report food-borne illness to their governing health agency, including the CDC. For guidelines around confirming a food-borne illness, health care professionals can reference, the Guide to Confirming an Etiology in Foodborne Disease Outbreak.

For more information and data regarding tracking and reporting Salmonella contact the CDC via their website or call 800-232-4696.