A salmonella outbreak that has sickened hundreds of people in at least 37 states is being linked to onions from Mexico, the Centers for Disease Control and Prevention announced Wednesday.
Public health officials have been investigating the source of the salmonella oranienburg strain since first receiving reports of infections in June. Last month, the agency appeared to have narrowed its focus on onions after the strain was found in a sample taken from a takeout condiment cup containing cilantro, lime and onions. The sick person had reportedly eaten all of the onions in the container.
As of Wednesday, the CDC has identified 652 people who became sick from an infection, with at least 129 hospitalized. There have been no deaths associated with the outbreak.
The agency noted that the true number of sick people may be much higher because most people recover without medical care and are not tested for Salmonella.
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Which onions are linked to the salmonella outbreak?
The impacted products include fresh whole red, white and yellow onions imported from Chihuahua, Mexico and distributed by ProSource Inc.
They were distributed nationwide and sold to restaurants and grocery stores throughout the United States. They may have a sticker or packaging with the brand name ProSource Inc. noting they were imported from Mexico.
ProSource officials said the onions were last imported on Aug. 27. However, these onions can last up to three months in storage, meaning some may still be in home kitchens and businesses.
In interviews with sick people, public health officials learned that 75% of those infected ate raw onions or dishes likely containing raw onions before they became ill. Several of the sick reported eating at the same restaurants, indicating to officials that they may be part of illness clusters.
The Food and Drug Administration conducted a traceback investigation and identified ProSource as a common supplier of imported onions to many of the restaurants where sick people ate.
Investigators are working to determine if other onions and suppliers may also be linked to the outbreak.
What to do if you have these contaminated onions
Consumers should thrown out onions that have stickers or packaging identifying the brand ProSource and Mexico. The CDC says if you cannot determine where the onions are from, throw them away, do not buy or eat them.
The agency also recommends washing surfaces and containers these onions may have touched with hot soapy water or in a dishwasher.
What do businesses do if they have these onions?
Businesses should not sell or serve these onions. The CDC says to check storage coolers for them. If you can't confirm where the onions are from, discard them.
Also, wash and sanitize any surfaces that may have come in contact with the onions.
What are the symptoms of salmonella?
Symptoms of salmonella include diarrhea, fever higher than 102 degrees Fahrenheit, stomach cramps, excessive vomiting and signs of dehydration. Symptoms can start six hours and up to six days after ingesting the bacteria.
In most cases, people recover without medical care after four to seven days. Some people – especially children younger than 5 years old, adults 65 years and older, and people with weakened immune systems – may experience more severe illnesses that require medical treatment or hospitalization.
Every year, salmonella causes about 1.35 million illnesses, 26,500 hospitalizations, and 420 deaths in the United States, according to the CDC.
To avoid getting sick with salmonella, the CDC recommends four safety measures when preparing food: washing hands, utensils and surfaces, separating raw food, using a food thermometer and refrigerating perishables within two hours.
Check out the CDC's salmonella Q&A page for more information.
How did raw onions get contaminated with salmonella?
It is not clear how the ProSource onions were contaminated with salmonella. Generally, salmonella outbreaks are linked to contamination from post-harvest handling when products come into contact with the bacteria during cutting, washing, packing and preparation processes.
But with this outbreak linked to whole raw onions, the contamination likely occurred pre-harvest. Researchers have found pre-harvest contamination happens when the plant is fertilized with contaminated manure or irrigated with contaminated water.