Hidden Threats Lurking: What Experts Fear After Cyclospora

Hot off the heels of the cyclospora outbreak, experts worry about what might come next, as they predict we are far from seeing the back of mass cases of foodborne illness. Listeria is the pathogen that keeps Jill Roberts up at night, though she has her eye on five others too.

"Listeria caused two of the deadliest foodborne outbreaks in the U.S., linked to cantaloupe and queso fresco," Roberts, a professor of public health at the University of South Florida, told Newsweek. "The Center for Disease Control and Prevention's (CDC) foodborne surveillance network, PulseNet, played a key role in detecting and stopping both outbreaks.

"However, with the laboratory currently under-resourced, and the state laboratories that send it data under-resourced, it is not clear if detection of the next Listeria outbreak will occur."

That uncertainty sits at the center of a growing alarm among public health experts.

After a cyclospora outbreak sickened thousands in the U.S., specialists warn that federal funding cuts have hollowed out the systems built to catch the next, deadlier pathogen before it spreads. Given the warming climate's impact on crops and infectious disease spread, they say, more foodborne outbreaks could be on the way—and the next could be far worse.

Central to the U.S.'s food safety system is FoodNet, a CDC program created after four children died from E. coli in the 1990s. Officially called the Foodborne Diseases Active Surveillance Network, it relies on participating states to contact laboratories for case data signaling emerging problems.

But under President Donald Trump's second term, the administration slashed billions of dollars in public health funding. It has also curtailed FoodNet, ending mandatory tracking of Cyclospora and other pathogens. Listeria surveillance under FoodNet, Roberts noted, was "discontinued" last year.

The Rise of Foodborne Illness

The stakes are steep as Listeria kills as many as 30 percent of people diagnosed with it, and infections can bring convulsions, miscarriage and organ-damaging sepsis.

Campylobacter, a bacteria tied to raw and undercooked poultry, which sickens roughly 1.5 million Americans a year, is also on the rise. About 60 people were sickened in an Idaho raw milk outbreak this year. A new study conducted by Ineos Oxford Institute researchers recently found that modern poultry farming practices have fueled a more than 100-fold rise in the spread of Campylobacter, making it the world's most common foodborne bacteria.

Meanwhile, the ongoing cyclospora outbreak remains unresolved.

As of July 13, more than 3,000 cyclosporiasis cases had been reported in Michigan and Ohio, with additional cases in West Virginia and Kentucky. Nationally, the CDC counts more than 7,000 confirmed or suspected cases across 34 states since May 1. Michigan officials suspect lettuce or salad greens, while federal officials expect the outbreak to persist through August as investigators trace the contamination.

Against this backdrop, Roberts says that several other pathogens are also on the rise.

"Shigella, enterohemorrhagic E. coli, Vibrio, and Yersinia have all increased in recent years," she said. "However, you must interpret this data with caution because laboratory testing has improved greatly."

Many infections, she said, likely went "undetected" for years but "are of greater impact than previously thought."

Shigella has a low infectious dose and is spreading in populations without access to clean food and water, she explained. Enterohemorrhagic E. coli, however, is spreading in raw milk, requiring stronger irrigation-water rules and a raw milk ban, in her view.

Vibrio "is spread in raw seafood," the professor added, mostly via raw oysters, while Yersinia "is spread in raw milk and undercooked pork"—both reversible through proper cooking and a raw milk ban, though Robert F. Kennedy Jr. continues to champion the consumption of raw dairy.

"Any pathogen could cause the next outbreak given the right circumstances," Roberts said. "But, statistically speaking, all roads lead to norovirus.

"It is the leading cause of foodborne illness, accounting for more than half of all sicknesses."

Norovirus season begins in October.

The Foodborne Illnesses That Could Make Headlines Next

• Norovirus: Roberts' top pick by far. Also called the winter vomiting bug, it is a stomach bug that causes vomiting and diarrhea.
• Listeria: The one the professor said she is "most worried about currently," given it is tied to two of the deadliest U.S. outbreaks on record and its mandatory FoodNet tracking was dropped last year, leaving detection capacity uncertain.
• Shigella: A group of bacteria that cause shigellosis, which is an infection of the intestines that often presents as diarrhea. It is rising in populations without reliable access to clean food or water, but it has a notably low infectious dose.
• Enterohemorrhagic E. coli: Spreading via raw produce; Roberts says it calls for stricter irrigation-water regulation and a ban on raw milk products.
• Vibrio: Linked mostly to raw oysters and other raw seafood; she recommends at-risk individuals avoid raw seafood altogether.
• Yersinia: Spread through raw milk and undercooked pork; she says proper cooking temperatures and a raw milk ban could reverse any harm.

Cyclospora is just one parasite among many capable of hiding in the foods Americans eat every day—and with surveillance weakened and a changing climate reshaping how food grows and disease spreads, experts like Roberts worry that conditions could ripen for something worse.

Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang