This year's cyclospora outbreak has put a spotlight on foodborne illness, but public health experts say cyclospora is far from the only pathogen worth watching.

Five other foodborne pathogens—listeria, shigella, enterohemorrhagic E. coli, vibrio and yersinia—have all seen documented increases in the U.S. in recent years, according to Dr. Jill Roberts, a professor of public health at the University of South Florida.

Roberts told Newsweek that while some of the rise reflects better laboratory detection, the pathogens are having a greater impact than previously understood, and each one spreads through different routes that require different fixes.

"We should consider how they are spreading and what to do about it," Roberts said.

The professor is most concerned about Listeria, given the strain on the surveillance systems meant to catch outbreaks early.

"Listeria is the pathogen I am most worried about currently," she said, noting that Listeria has caused two of the deadliest foodborne outbreaks in U.S. history, tied to cantaloupe and queso fresco.

She said the Centers for Disease Control and Prevention's (CDC) PulseNet network was critical to detecting and stopping both outbreaks, but that the network—and the state laboratories that feed it data—are now under-resourced. And listeria surveillance under the CDC's FoodNet program was discontinued last year, she said.

Here is what to know about each pathogen.

Listeria

Listeria monocytogenes is a bacterium that can contaminate ready-to-eat foods, soft cheeses and deli meats.

Symptoms include fever, muscle aches, and gastrointestinal issues, and the infection can be especially dangerous for pregnant women, newborns, older adults and people with weakened immune systems, sometimes leading to miscarriage, meningitis or death.

A 2025 Listeria outbreak linked to prepared pasta meals sold at Walmart, Kroger and Trader Joe's sickened 28 people across 19 states, hospitalizing 27 and killing seven, with one pregnancy resulting in fetal loss. The CDC closed that investigation in February. A separate outbreak tied to soft cheese, including requesón, has sickened at least eight people in three states since June.

Shigella

Shigella causes shigellosis, an infection marked by diarrhea that can be bloody, fever and stomach cramps. It spreads easily between people and through contaminated food, requiring only a small number of organisms to cause infection.

The CDC has warned of a rise in extensively drug-resistant Shigella strains, which climbed from zero percent of cases between 2011 and 2015 to 8.5 percent in 2023, with no FDA-approved oral antibiotics available to treat them.

Roberts said Shigella's low infectious dose allows it to spread in populations without reliable access to clean food and water, including people experiencing homelessness.

Enterohemorrhagic E. Coli

This strain of E. coli, including O157:H7, produces toxins that can cause severe stomach cramps, bloody diarrhea and, in serious cases, hemolytic uremic syndrome, a form of kidney failure. Symptoms also include fever, nausea and vomiting.

A 2026 outbreak linked to raw cheddar cheese and raw milk from Raw Farm sickened nine people in three states. Roberts said the pathogen is spreading through raw produce and raw milk, and called for stronger regulations on irrigation water and a ban on the sale of raw milk and raw milk products.

Vibrio

Vibrio bacteria, including Vibrio vulnificus, live in warm coastal and brackish water and can cause severe gastrointestinal illness or, through open wounds, dangerous skin and tissue infections often described as "flesh-eating."

About one in five people with a Vibrio vulnificus infection die.

Florida recorded 12 cases and one death from Vibrio vulnificus this year as of late July, following 33 cases and five deaths in 2025. Louisiana logged 34 infections and six deaths last year, several tied to raw oysters.

Roberts said most cases are linked to raw oysters and that at-risk people should avoid raw seafood.

Yersinia

Yersinia enterocolitica causes yersiniosis, with symptoms including fever, diarrhea and abdominal pain from inflamed lymph nodes. Young children and older adults face the highest risk. It is most commonly linked to raw or undercooked pork but has also been tied to contaminated raw milk.

Roberts said proper cooking temperatures and a ban on raw milk products could help reverse the pathogen's rise.

Roberts said norovirus remains the leading cause of foodborne illness overall, accounting for more than half of all cases, with its seasonal surge typically beginning in October and continuing through winter.

Contact Newsweek editors on this story: Kara Dolman and Gray R. Thomas