Trucks to tables
Cyclosporiasis outbreak draws scrutiny to path of lettuce from Mexico
SPOTLIGHT| PUBLIC HEALTH
Don't blame your salad if you got sick in the outbreak of cyclosporiasis, an intestinal illness linked to contaminated iceberg lettuce. Instead, blame what's on it.
Cyclospora cayetanensis is a tough microscopic parasite that can give you frequent, watery diarrhea. It can be found on produce and isn't easily removed by washing or common sanitizers.
At least 12,218 cyclosporiasis cases were confirmed, and an additional 12,255 reported to the U.S. Centers for Disease Control and Prevention but not yet laboratory confirmed, as of Aug. 5. Cases were recorded in 45 states. Two deaths were reported.
A Food and Drug Administration investigation linked the outbreak to iceberg lettuce served at Taco Bell restaurants sourced from privately held Taylor Farms operations in central Mexico. Walmart, Sysco and Taco Bell removed potentially affected lettuce. Health officials are searching for other potential sources.
The connection to lettuce raised questions on how and where food is grown, processed and imported. Here's a closer look.
How does it get here?
1 The recalled lettuce was grown in central Mexico at a specific independent farm and was voluntarily recalled in the United States by Taylor Farms de Mexico in Guanajuato on July 17, the FDA said. The farm was not identified.
2 The lettuce was processed, including being chopped or shredded, in central Mexico, Taylor Farms said. It was packaged in 5-pound bags. Cases containing four 5-pound bags each were used for shipping.
3 The processed lettuce was shipped, likely in refrigerated trucks. Where it was loaded was not identified.
4 Fresh lettuce from Mexico typically arrives to a warehouse via what's called a cold chain. That's a system of refrigerated trucks, warehouses and transfer points used to keep the lettuce cold.
5 Trucks enter the U.S. via one of six points of entry. For lettuce coming from central Mexico, especially the BajÃo/Guanajuato region, the closest and most likely border gateways are in south Texas.
6 Specialized short-distance trucks cross the border into the U.S. On arrival, the produce passes through customs and border drayage — a specialized short-distance trucking route that bridges the gap between national borders.
7 Lettuce is transferred to U.S. distribution trucks. After clearing customs, it is taken to a cold-storage or cross-dock facility, where it's transferred from one refrigerated truck to another.
8 A U.S.-licensed carrier usually completes delivery. Imported food cleared by federal agencies and released for commerce can move through normal supply chains to a retail or wholesale distributor or other commercial buyer. Retailers include supermarkets, warehouse clubs or convenience stores. Food-service distributors like Sysco or US Foods can supply restaurants, hotels, schools or hospitals.
9 The lettuce ends up on tables across the country.
How does it get tainted?
The parasite comes mainly from people — "humans appear to be the only major host," according to the CDC. Field produce can be contaminated by people who carry cyclospora and may not be able to practice good hygiene.
The parasite can be shed in human feces and spread to fresh produce and irrigation water. Contamination can happen almost anywhere along the supply chain.
"And so there is really a wide potential for areas for contamination, which is why training, good hygiene practices, cleaning and sanitizing are so critical throughout that entire process," Kalmia Kniel, a professor of animal and food sciences at the University of Delaware, said in a July 28 briefing.
How much is imported?
Much of the produce consumed in the U.S. is produced domestically but the amounts vary depending on the vegetable. About 8% of the lettuce sold in the U.S. each year is imported, according to the FDA.
Mexico accounted for about 88% of the lettuce imported in 2024, and Canadian imports accounted for about 11%, Forbes reported.
California grows about two-thirds of the domestic lettuce supply, with peak season from April to October, while Arizona has peak harvesting seasons between November and March. Experts say imported lettuce from Mexico helps fill some of the off-season supply gap.
As domestic production hits its limits, the U.S. turned to imports to help meet year-round demand.
U.S. lettuce production overall stayed relatively flat, said James Sayre, agricultural trade economist at UC Davis, largely because domestic locations with ideal growing conditions for lettuce are maxed out.
In May, the U.S. imported almost 28,000 metric tons of lettuce from Mexico, based on the data from the U.S. Department of Agriculture. That's an increase of almost 50% compared to the same month last year. It also totaled a record import value, worth more than $50 million.
