A cyclospora parasite outbreak has spread to at least 34 states, with nearly 7K cases confirmed or under investigation nationwide as of mid-July, according to the CDC.

Michigan has been hit hardest, with over 3.3K confirmed cases and 44 hospitalizations. Nationally, 141 people have been hospitalized since illnesses first appeared in May. No deaths have been reported.

The CDC says this is one of the largest foodborne illness outbreaks in the US in years. A typical year sees roughly 2.7K cyclospora cases. Cases span ages 2 to 95, and more than half of those infected are women.

Michigan health officials flagged lettuce and salad greens as a possible source after interviewing more than 1.7K infected people, about half of whom reported eating leafy greens before getting sick. But no single product, grower, retailer, or distributor has been formally implicated, and no recalls have been issued.

The industry's financial exposure

The uncertainty is already hitting the produce sector. The US lettuce industry moved 1.36 billion pounds of fresh lettuce last year, generating $3.79B in retail sales. Fresh spinach added another $1.26B.

Producers say orders are being pulled even from suppliers with no known connection to the outbreak.

Leafy greens have a short shelf life, so canceled orders translate almost immediately into lost revenue. When demand falls fast, growers often till unharvested crops back into the soil rather than pay to harvest produce that won't sell.

The damage can linger long after an outbreak is resolved. A 2006 E. coli outbreak traced to a single California spinach farm dragged down spinach sales across the category for months. Consumers rarely distinguish between brands or suppliers when a food group makes headlines.

Taco Bell confirmed it had voluntarily removed some ingredients at select locations as a precaution, though public health officials have not linked the chain to the outbreak.

What shoppers are doing

Behavior is already shifting. New York diners reported avoiding salad orders at chains like Sweetgreen and Just Salad. NYC has logged at least 374 cases since May 1, above typical levels.

Experts recommend avoiding bagged salad kits and opting for whole head lettuce, discarding the outer two to three leaves, and washing inner leaves under running water. Cooking vegetables to 158 degrees Fahrenheit kills the parasite entirely.

Chlorine and household soaps won't neutralize cyclospora and may leave harmful residues, so plain running water and physical scrubbing remain the recommended method.

The CDC expects additional cases to emerge through August, meaning the pressure on the fresh produce market is unlikely to lift soon.