FDA Traces a Salmonella Outbreak to Imported Whole Onions (2021)

Table of Contents

1. What the FDA Announced on October 20, 2021
2. How Investigators Linked the Illnesses to Onions
3. Salmonella Oranienburg and Salmonellosis, per the FDA
4. The Two Recalls and the Downstream Lists
5. How the Case Count Grew
6. Import Screening, Importer Inspections and Work With Mexico
7. What the FDA Page Tells Readers Now
8. What the Investigation Did Not Establish
9. Dates and Status as of October 18, 2026
10. How It Fits Other FDA Onion and Produce-Safety Actions
11. Primary Documents
12. Key Research Papers
13. Connections
14. Featured Videos

1. What the FDA Announced on October 20, 2021

The FDA’s outbreak page, “Outbreak Investigation of Salmonella Oranienburg: Whole, Fresh Onions (October 2021),” opened with an update dated October 20, 2021. It stated that the FDA, “along with CDC and state and local partners, is investigating a multistate outbreak of Salmonella Oranienburg infections linked to whole, fresh onions.”

The same update reported that the FDA’s traceback investigation, though still ongoing, had identified an Idaho produce supplier as a source of potentially contaminated whole, fresh onions imported from the State of Chihuahua, Mexico. That supplier agreed to voluntarily recall red, yellow and white onions imported from Chihuahua with import dates from July 1 through August 27, 2021.

A traceback, as the FDA’s outbreak-investigations page describes it, is used “to identify the source and distribution of the implicated food and remove the contaminated product from the marketplace,” to tell apart two or more suspected foods, and to find possible routes or sources of contamination. The FDA describes the investigation as carried out “in cooperation with the Mexican competent authorities” — Mexico’s food-safety regulators.

This was an outbreak investigation, not a rule. No Federal Register document (the U.S. government’s daily publication of rules and official notices) was issued for it; the record is the FDA outbreak page and its dated updates.

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2. How Investigators Linked the Illnesses to Onions

The FDA’s October 20 update set out three lines of evidence:

• Restaurant clusters. Epidemiological data collected by CDC and state and local investigators identified 20 illness clusters at restaurants where onions were served. A cluster here means a group of sick people who ate at the same place. The FDA wrote that information from these clusters “shows that many ill people ate raw onions,” and that investigators worked to find a common food eaten by all of the sick people.
• One positive food sample. State officials collected food items from some of the restaurants. The outbreak strain was found in a sample from a takeout condiment cup containing cilantro and lime. The sick person reported that the cup had also contained onions, but none were left in it when it was tested. In the FDA’s words, because several foods were in the container and in the sample, “it is not possible to know which food item was contaminated.”
• A common supplier. The traceback identified the Idaho supplier as a common supplier for many of the restaurants where sick people reported eating, including the restaurant where the condiment-cup sample was collected.

On October 21, 2021, the FDA reported that its traceback had identified a second supplier of onions from Chihuahua as “an additional common supplier” for many of the restaurants where sick people ate.

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3. Salmonella Oranienburg and Salmonellosis, per the FDA

Salmonella is a group of bacteria. Oranienburg is the name of one serotype, a subtype of Salmonella told apart by laboratory testing. The site’s Salmonella Typhimurium page covers a different serotype; this outbreak was serotype Oranienburg.

The FDA’s Salmonella page, linked from the outbreak page, describes the illness these bacteria cause:

• The illness. Salmonella “can cause gastrointestinal illness and fever called salmonellosis.”
• Timing. Most people infected begin to develop symptoms 12 to 72 hours after infection; the illness usually lasts four to seven days, and most people recover without treatment.
• Symptoms. Most people with salmonellosis develop diarrhea, fever and abdominal cramps. More severe cases may include a high fever, aches, headaches, lethargy, a rash, or blood in the urine or stool, and in some cases may become fatal.
• Who is at higher risk. Children younger than five, the elderly and people with weakened immune systems are more likely to have severe infections.
• How it spreads. The page lists food handlers who do not wash hands, surfaces or tools between food-preparation steps, eating raw or undercooked foods, and contact with certain animals.

The FDA’s 2022 bulb-onion strategy (section 10) notes that bulb onions can be “consumed raw as an ingredient or garnish,” which matches the outbreak page’s finding that many ill people ate raw onions. Bacterial infections in general are covered on the site’s Bacterial Infections page.

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4. The Two Recalls and the Downstream Lists

A voluntary recall is one a company carries out itself, here after meeting with the FDA, rather than under a court or agency order. The FDA outbreak page records two:

• October 20, 2021 — the Idaho supplier. A voluntary recall of red, yellow and white whole, fresh onions imported from the State of Chihuahua, Mexico, with import dates from July 1, 2021 through August 31, 2021 (the FDA’s October 20 update had given August 27).
• October 22, 2021 — the second supplier. The FDA’s October 21 update reports that when the FDA met with this firm, it agreed to recall all red, yellow and white onions imported from Chihuahua from July 1 through August 31, 2021. Its recall, issued October 22, covered onions imported from July 1 through August 25, 2021, “when the last shipment of onions from the State of Chihuahua, Mexico was received by the firm.”

The recalls then spread down the supply chain. On October 29, 2021, the FDA posted a list of additional recalls by retailers that may have received the recalled onions, including companies that “further processed the onions by using them as ingredients in new products or by repackaging them.” The FDA also published lists of retail establishments that received recalled product: one for the Idaho supplier’s onions on October 29 and one for the second supplier’s on November 2, 2021.

The FDA attached a caution to those store lists: they “represent the best information currently available to the FDA; however, they may not include all retail establishments that have received the recalled product or may include retail establishments that did not actually receive the recalled product.” The page pointed readers to the product details in each firm’s recall announcement alongside the lists.

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5. How the Case Count Grew

All case figures below are CDC’s counts as the FDA outbreak page reports them.

• October 29, 2021: 808 illnesses across 37 states and Puerto Rico.
• November 12, 2021: 892 illnesses in 38 states and Puerto Rico.
• Final count (outbreak declared over as of February 2, 2022): 1,040 illnesses, 260 hospitalizations and no deaths, in 39 states, Washington, D.C. and Puerto Rico. The last illness began on January 1, 2022. The FDA lists product distribution as nationwide.

The onions also reached Canada. As of October 29, 2021, the FDA reported that the Canadian Food Inspection Agency had issued an advisory for recalled onions imported into Canada, and that there were no illnesses in Canada linked to the outbreak.

For scale, the FDA’s 2022 bulb-onion strategy states that the 2020 and 2021 Salmonella outbreaks linked to bulb onions grown in the U.S. and Mexico together caused “more than 2,100 confirmed cases of foodborne illness in the United States,” and estimates that the 2021 outbreak cost “$188 million in consumer health-related losses.”

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6. Import Screening, Importer Inspections and Work With Mexico

The FDA outbreak page describes three steps beyond the recalls:

• Enhanced import screening (September 2021). While the source was still being sought, FDA import operations put in place enhanced screening for Salmonella in onions imported into the United States. No samples were collected, the FDA wrote, “because the growing season had ended and onions were no longer being imported from the State of Chihuahua, Mexico.”
• Inspections of U.S. importers. After the outbreak the FDA began onsite domestic investigations and Foreign Supplier Verification Program (FSVP) inspections of U.S. firms that had imported onions from Chihuahua. The FDA’s FSVP rule page explains that an FSVP is a program covered importers must have in place to verify that their foreign suppliers produce food with “the same level of public health protection as the preventive controls or produce safety regulations,” and that the food is not adulterated. By inspecting importers, the outbreak page says, the FDA can check whether they are “performing certain risk-based activities to verify that imported foods meet U.S. safety standards.”
• Work with Mexican authorities. The FDA continued to work with Mexican competent authorities through the established Food Safety Partnership to look for possible sources of contamination in the implicated region and to put prevention measures in place before the next growing season. It also said it intended to consider “additional tools, such as import screening and sampling,” for onions grown and harvested in Chihuahua during the next season.

The FDA’s partnership page explains that the FDA-SENASICA-COFEPRIS Food Safety Partnership was set up in September 2020 between the FDA and two Mexican agencies: the National Service of Agro-Alimentary Health, Safety and Quality (SENASICA) and the Federal Commission for Protection against Sanitary Risk (COFEPRIS). It states that roughly one third of all FDA-regulated human food imported into the U.S. comes from Mexico, including 60% of fresh produce imports. Among the partnership’s reported work, the page (current as of March 12, 2026) lists a virtual technical workshop for bulb-onion producers in Chihuahua with 70 participants, and visits by the Mexican agencies to 45 farms and 15 packinghouses in Chihuahua using an FDA bulb-onion information-collection tool; the page does not date these steps.

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7. What the FDA Page Tells Readers Now

The final version of the FDA outbreak page, content current as of February 2, 2022, reads: “CDC has announced the outbreak is over. There are no recommendations for consumers, retailers, or suppliers.”

The page’s contact section states that consumers who have symptoms are directed to their health care provider “to report their symptoms and receive care,” and that complaints or adverse events, including illness, can be reported to the FDA through its Industry and Consumer Assistance pages. These are the FDA’s statements; questions about any illness belong with a clinician.

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8. What the Investigation Did Not Establish

• The outbreak strain was not found in an onion. The only positive food sample described on the FDA page was the mixed condiment cup of cilantro and lime, and the FDA states that it is not possible to know which food in it was contaminated.
• No root cause was found. The FDA’s 2022 bulb-onion strategy states that the agency “was unable to conduct an on-farm investigation at the time, and no conclusive root-cause was determined.”
• No import samples were taken. The September 2021 import screening collected no samples because the Chihuahua growing season had ended.
• The recalls were limited. They covered whole red, yellow and white onions from Chihuahua imported in July and August 2021 (and products made with them), not onions in general.
• It was not a rule. The investigation set no new legal requirement for growers or importers.

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9. Dates and Status as of October 18, 2026

• September 2021: FDA import operations begin enhanced Salmonella screening of imported onions; no samples are collected.
• October 20, 2021: the FDA announces the investigation; the Idaho supplier begins its voluntary recall.
• October 21–22, 2021: the traceback identifies a second common supplier, which recalls its Chihuahua onions.
• October 29 and November 2, 2021: the FDA posts lists of downstream recalls and of retail establishments that received recalled onions.
• November 12, 2021: 892 illnesses in 38 states and Puerto Rico.
• February 2, 2022: CDC declares the outbreak over: 1,040 illnesses, 260 hospitalizations, no deaths.
• July 2022: the FDA posts its strategy to help prevent salmonellosis outbreaks associated with bulb onions (section 10).

Status as of October 18, 2026: closed. The FDA page states, “FDA investigation has ended; CDC has declared outbreak over.” A check of the Federal Register for FDA documents on onions and Salmonella from 2021 through October 18, 2026 found no document about this outbreak. The three documents it returned are the December 2021 agricultural water proposed rule, the agricultural water final rule published May 6, 2024 (89 FR 37448, effective July 5, 2024), and the November 2022 traceability final rule (section 10).

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10. How It Fits Other FDA Onion and Produce-Safety Actions

• Summer 2020 — red onions and Salmonella Newport. The FDA’s report on that outbreak, posted in 2021 (content current as of May 13, 2021), describes 1,127 reported U.S. illnesses and 515 Canadian cases linked to red onions grown in California, and calls it “the largest Salmonella outbreak in over a decade.” It notes that whole red onions, a raw agricultural commodity, “had not been previously associated with a foodborne illness outbreak.” No conclusive root cause was found; the report’s leading hypothesis was contaminated irrigation water used in one growing field.
• Fall 2021 — this outbreak. Onions from a different country, a different serotype, and a second year in a row of a large onion-linked Salmonella outbreak.
• December 2021 — farm water. In the same season the FDA proposed new rules for the water used on produce farms before harvest, reported on the site’s Agricultural Water Proposed Rule page.
• July 2022 — the bulb-onion prevention strategy. The FDA’s strategy page says the agency began developing these measures in fall 2020, began carrying them out in summer 2021, and updated them in winter 2021 “to account for the 2021 bulb onion outbreak.” The measures it lists include prioritizing inspections of bulb-onion farms in the U.S. and Mexico covered by the FDA’s Produce Safety Rule, studying onion curing and soil conditions, supporting industry best practices, prioritizing FSVP inspections of bulb-onion importers, increasing “strategic and targeted sample collection and testing of imported bulb onions from the State of Chihuahua, Mexico,” and continuing the Food Safety Partnership with Mexico.
• November 2022 — traceability records. The FDA’s food traceability final rule requires additional records for certain foods; it is reported on the Food Traceability Final Rule page. This page does not state whether onions are among the foods that rule covers.
• 2023 — another produce outbreak. The FDA’s investigation of a cantaloupe-linked Salmonella outbreak is reported on the Cantaloupe Salmonella Outbreak page.

The other major FDA actions of the year are collected on the FDA Actions of 2021 hub.

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11. Primary Documents

1. U.S. Food and Drug Administration. Outbreak Investigation of Salmonella Oranienburg: Whole, Fresh Onions (October 2021). Outbreak investigation page with dated updates of October 20, 21, 27 and 29 and November 2 and 12, 2021; final update, content current as of February 2, 2022 — fda.gov onion outbreak investigation
2. U.S. Food and Drug Administration. Summary of FDA’s Strategy to Help Prevent Salmonellosis Outbreaks Associated with Bulb Onions. Posted July 2022, content current as of September 26, 2022 — fda.gov bulb onion strategy
3. U.S. Food and Drug Administration. Factors Potentially Contributing to the Contamination of Red Onions Implicated in the Summer 2020 Outbreak of Salmonella Newport. Report, content current as of May 13, 2021 — fda.gov 2020 red onion report
4. U.S. Food and Drug Administration. Salmonella (Salmonellosis). Foodborne pathogens page, content current as of March 29, 2019 — fda.gov Salmonella page
5. U.S. Food and Drug Administration. FSMA Final Rule on Foreign Supplier Verification Programs (FSVP) for Importers of Food for Humans and Animals. Program page, content current as of May 1, 2026 — fda.gov FSVP rule page
6. U.S. Food and Drug Administration. FDA-SENASICA-COFEPRIS Food Safety Partnership. Program page, content current as of March 12, 2026 — fda.gov Food Safety Partnership page
7. U.S. Food and Drug Administration. Investigations of Foodborne Illness Outbreaks (definitions of outbreak-investigation terms, including traceback) — fda.gov outbreak investigations page
8. The two suppliers’ recall announcements and the FDA’s list of related downstream recalls are linked from the FDA outbreak page above. Their addresses carry the firms’ names, so they are not linked here.

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Key Research Papers

1. Mitchell MR Jr, Kirchner M, Schneider B, McClure M, Neil KP, Madad A, Jemaneh T, Tijerina M, et al. (2024). Multistate outbreak of Salmonella Oranienburg infections linked to bulb onions imported from Mexico - United States, 2021. Food Control 160:110325 — PubMed PMID: 39493539
2. McCormic ZD, Patel K, Higa J, Bancroft J, Donovan D, Edwards L, Cheng J, Adcock B, et al. (2022). Bi-national outbreak of Salmonella Newport infections linked to onions: the United States experience. Epidemiology and Infection 150:e199 — PubMed PMID: 36382397
3. Denich L, Cheng JM, Smith CR, Taylor M, Atkinson R, Boyd E, Chui L, Honish L, et al. (2024). A multi-provincial outbreak of Salmonella Newport infections associated with red onions: A report of the largest Salmonella outbreak in Canada in over 20 years. Epidemiology and Infection 152:e106 — PubMed PMID: 39344903
4. Graham-Glover B, Pereira E, Jefferson S, Blessington T, Armstrong M, Schwensohn C, Wilson C, Cromwell A, et al. (2026). Multistate Outbreak of Salmonella Thompson Infections Linked to Diced Onions-2023. Foodborne Pathogens and Disease 23(10):693-700 — PubMed PMID: 40956677
5. Racine J, Nerney A, Kilgore S, Darner J, Spets M, Critzer F, Harris LJ, Reitz S, et al. (2024). Irrigation Method Matters: Contamination and Die-off Rates of Escherichia coli on Dry Bulb Onions After Overhead and Drip Irrigation in Washington State (2022-2023). Journal of Food Protection 87(9):100326 — PubMed PMID: 38977079
6. Khajanchi BK, Grocholl J, Alam MS, Hasan NA, Wang H, Hughes S (2026). Colonization of Salmonella Newport and Microbiome Analyses of Bulb Onions Grown in Artificially Contaminated Soil at Lab-Scale Under a Controlled Environment. Journal of Food Protection 89(5):100769 — PubMed PMID: 41921618

The first paper is the published report of this 2021 outbreak investigation. The second and third describe the 2020 red-onion Salmonella Newport outbreak in the United States and in Canada, and the fourth a 2023 outbreak linked to diced onions. The last two are field and laboratory studies of bacterial contamination of bulb onions from irrigation water and from soil.

PubMed Topic Searches

1. PubMed: Salmonella outbreaks linked to onions
2. PubMed: Salmonella Oranienburg
3. PubMed: bulb onions and irrigation water contamination

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Connections

• FDA Actions of 2021
• FDA and Regulation
• Onions
• Vegetables
• Salmonella Typhimurium (a different serotype)
• Bacteria
• Bacterial Infections
• Agricultural Water Proposed Rule (2021)
• Food Traceability Final Rule (2022)
• Cantaloupe Salmonella Outbreak (2023)
• Closer to Zero Action Plan (2021)
• Voluntary Sodium Reduction Targets (2021)

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