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Salmonella 101: What you need to know
01:09 - Source: CNN
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Every so often, the food in your fridge winds up in the news when there’s an outbreak of illness linked to what we eat. A new US Centers for Disease Control and Prevention report details the foodborne illnesses that struck most often in 2018.

Researchers identified campylobacter, a bacteria most often found in chicken, raw milk and water, as the No. 1 cause of bacterial foodborne illness since 2013. In 2018, it was followed by salmonella, shiga toxin-producing E. coli, shigella and vibrio in the number of cases per 100,000 people.

The report included laboratory-diagnosed infections caused by eight pathogens at 10 US sites covering 15% of the population. In 2018, 25,606 illnesses, 5,893 hospitalizations and 120 deaths were identified.

The incidence of most infections is increasing, the report noted, but the research has some limitations. Testing changes might identify more cases, making trends hard to interpret, and large outbreaks might not indicate a sustained trend.

Here are some of the most common causes of foodborne illnesses last year.


Campylobacter causes more than a million illnesses throughout the United States every year, the CDC estimates. The bacteria is transferable to humans from animals that show no signs of infection. Poultry is a major source, the report says. In 2018, the US Department of Agriculture’s Food Safety and Inspection Service detected campylobacter in 18% of chicken carcasses and 16% of chicken parts sampled.

Campylobacter, which causes diarrhea, hospitalized 18% of patients, according to the report. The bacteria can also cause a rare neurological complication, Guillain-Barré syndrome.

Dr. Patricia Griffin, an author of the report and chief of the CDC’s Enteric Diseases Epidemiology Branch, said it was no surprise to see campylobacter at the top of the list.

“It is the most commonly isolated bacteria cause of foodborne illness in the United States, and it’s been that way for a long time,” Griffin said. “It doesn’t get a lot of respect and is not that well-known because it tends to not be found in a lot of multistate outbreaks.”


Salmonella is found in animal products such as pork, chicken and eggs, in addition to vegetables and fruits. The most common type of this bacteria that causes foodborne illness is salmonella enteritidis, and infections have not declined over 10 years, the report said.

“Salmonella causes more hospitalizations and deaths than campylobacter,” Griffin said.

“Approximately 450 deaths occur each year from the 1.2 million cases of salmonellosis that occur in the US. Individuals that are particularly susceptible to Salmonella infection include the very young, the very old and people with weakened immune systems,” said Catherine Donnelly, a professor of food science at the University of Vermont who was not involved in the new report.

Symptoms usually begin 12 to 72 hours after consuming the bacteria and can last four to seven days. They include diarrhea, fever and stomach cramps, according to the CDC. Most people recover on their own. Patients who experience severe diarrhea may require hospitalization. If severely ill patients are not treated, the illness can be deadly.


Compared to 2015-17, the incidence of of vibrio rose 109% in 2018, according to the report. Vibrio bacteria in raw oysters has emerged as a leading cause of illness in the United States and is associated with rising water temperatures, Donnelly said. Vibrio tends to be found in warmer coastal waters between May and October.

Humans can contract vibrio by consuming shellfish, such as oysters, that aren’t fully cooked. Symptoms range from mild intestinal problems to serious infections that result in amputation of limbs, the CDC said.

“Serious complications of vibrio illnesses are relatively uncommon,” Griffin said. “People who are at high risk of complications may want to think twice before eating raw oysters.”


There were 332 cases of the parasite cyclospora in 2018, an increase of 399% over 2015-17, the report said. Researchers said it was in part related to large outbreaks linked to produce.

People can develop the illness when they consume food or water contaminated with infected feces. Because cyclospora is more commonly found in tropical and subtropical parts of the world, outbreaks within the United States are mostly associated with produce imported from other countries.

Avoiding foodborne illnesses

The report notes that improved agricultural practices are needed to stop produce-related outbreaks, and the US Food and Drug Administration is implementing routine inspections of large produce farms and providing assistance to the produce industry to help outbreak investigations and prevent contamination.

“The CDC report shows that there has been progress made in areas in the battle against foodborne diseases, but there remains work to be done,” FDA representative Peter Cassell wrote in an email.

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Consumers can have a hand in this process, as well.

“Consumers may not realize how powerful they are,” Griffin said. “A lot of the major legislation for food safety has happened because consumers really demanded it. It’s important for consumers to be informed about sources of foodborne illnesses so they can be part of advocating for safer foods.”

At home, proper handwashing, thoroughly cooking food, cleaning cooking spaces and avoiding contaminated water and produce reduce your chance of encountering bacteria or parasites. If you think you have a foodborne illness, talk to a health care provider.