Onions are one of the most commonly consumed vegetables in the United States. Grown in more than 170 countries, they are also one of the most important horticultural crops worldwide. Bulb onions are characterized by having hollow, tubular, blue-green leaves and can be purchased fresh or frozen to use in cooked dishes or consumed raw as an ingredient or garnish. Bulb onions are typically dried or cured to reduce decay and increase shelf life.
In 2020 and 2021, Salmonella outbreaks associated with the consumption of bulb onions produced in the U.S. and Mexico caused more than 2,100 confirmed cases of foodborne illness in the United States. The 2020 outbreak in the U.S. cost an estimated $203 million in consumer health-related losses. The 2021 outbreak in the U.S. cost an estimated $188 million in consumer health-related losses. 
Overview of Salmonellosis Outbreaks Associated with Bulb Onions
In 2020, the FDA’s Coordinated Outbreak Response & Evaluation (CORE) Network, in collaboration with the Centers for Disease Control and Prevention (CDC) and state and local partners, investigated a multistate outbreak of Salmonella Newport infections linked to the consumption of domestically grown red bulb onions. While no conclusive root cause could be identified, the agency’s investigation report identified several plausible opportunities for contamination including irrigation water, sheep grazing on adjacent land, and signs of animal intrusion, such as scat and large flocks of birds that may spread contamination.
In 2021, the FDA led investigations of a multistate outbreak of Salmonella Oranienberg infections linked to the consumption of red, white, and yellow bulb onions imported from the State of Chihuahua, Mexico. The FDA worked closely with Mexican competent authorities through the established Food Safety Partnership to investigate potential source(s) of contamination within the implicated region. However, the agency was unable to conduct an on-farm investigation at the time, and no conclusive root-cause was determined.
Summary of FDA’s Strategy to Help Prevent Future Outbreaks of Salmonellosis linked to Bulb Onions
Food safety is a shared responsibility. The bulb onion industry is responsible for meeting applicable food safety requirements. In addition, the FDA believes it is imperative that we share data, knowledge, and information and work collaboratively with industry and state regulators to enhance food safety and advance the goals and objectives of FDA’s Strategy for the Safety of Imported Food. Based on review of the outbreak investigational findings, historical data, and engagements with industry and other stakeholders, the agency has identified several measures that can be taken to reduce future incidences of foodborne illness related to bulb onions, including:
- Engaging domestic and foreign industry and government partners to promote a broad understanding of the outbreak investigation findings, applicable Produce Safety Rule requirements, and the importance of root cause analysis after outbreaks.
- Prioritizing inspections of bulb onion farms in the United States and Mexico that are covered by the FDA’s Produce Safety Rule.
- Identifying and assessing practices and conditions associated with onion curing.
- Supporting research efforts to better understand bulb onion production practices, including the impact of different soil conditions and curing practices on the safety of bulb onions.
- Supporting industry-led efforts to develop and implement best practices for bulb onion production.
The agency has also identified the following additional actions specific to imported bulb onions:
- Prioritizing Foreign Supplier Verification Program inspections of bulb onion importers to ensure that onion importers are verifying that foreign suppliers follow processes and procedures that provide the same level of public health protection as U.S. food safety requirements.
- Increasing strategic and targeted sample collection and testing of imported bulb onions from the State of Chihuahua, Mexico.
- Continuing to collaborate with Mexican competent authorities through the established Food Safety Partnership to help ensure the safe production of bulb onions in the State of Chihuahua, Mexico.
By implementing these activities, the FDA seeks to:
- Encourage high rates of compliance with the applicable FDA food safety requirements across the bulb onion supply chain through education, outreach, and technical assistance to the growers, distributers, and importers of bulb onions.
- Verify and measure the rate of industry compliance through inspections and sampling.
- Broaden scientific knowledge about production methods that can reduce future incidences of foodborne illness related to bulb onions.
 The estimated consumer health losses were calculated using information and methods in the following documents:
Minor, T., Lasher, A., Klontz, K., Brown, B., Nardinelli, C. and Zorn, D. (2015), The Per Case and Total Annual Costs of Foodborne Illness in the United States. Risk Analysis, 35: 1125-1139. https://doi.org/10.1111/risa.12316
Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson M-A, Roy SL, et al. Foodborne illness acquired in the United States—major pathogens. Emerg Infect Dis [serial on the Internet]. 2011 Jan [date cited]. http://dx.doi.org/10.3201/eid1701.P11101
 FDA started developing these strategies in Fall 2020 and began implementing them in Summer 2021. The strategies were subsequently updated in Winter 2021 to account for the 2021 bulb onion outbreak.