Salmonella outbreaks in Minnesota: What you need to know

Salmonella bacteria
This colorized scanning electron micrograph depicts a colony of Salmonella Typhimurium bacteria.
Janice Haney Carr | Centers for Disease Control and Prevention

Minnesota has experienced a rash of salmonella infections in recent weeks linked to grocery stores and restaurants. The latest involves a number of Minnesota Chipotle locations.

Here's what you need to know about salmonella and the recent infections.

What do we know about the latest outbreak involving Chipotle?

It appears to be a big outbreak. In just a week's time, 58 salmonella cases were reported to the Minnesota Department of Health. That's an unusually high number of cases for such a short amount of time.

When disease investigators interviewed many of these people, they learned that at least 41 of the victims ate, or likely ate, at one of 21 different Chipotle locations in the Twin Cities metro area, St. Cloud, Rochester and Mankato.

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What food item caused the outbreak?

Investigators suspect it is linked to a particular type of produce, but they aren't disclosing which kind until they have laboratory confirmation.

The health department says Chipotle has changed its supplier of that item, so the agency is confident that the transmission of salmonella stopped. But it expects the size of the outbreak to grow, considering the number of restaurants involved.

Based on experience, officials suspect some people who got sick from salmonella after eating at Chipotle didn't seek medical care. Those people may still not need care, but the health department would like them to report their illness to their health care providers anyway.

What other salmonella outbreaks are going on in Minnesota?

State health officials are also investigating a separate cluster that has sickened a dozen people here and more than 300 elsewhere in the United States. That outbreak is associated with dark green slicer cucumbers found in some grocery stores and restaurants. So far, 70 people have been hospitalized and there have been two deaths. A Minnesota woman who was made ill has sued the California produce distributor linked to the cucumbers.

There was a salmonella outbreak in Minnesota tied to frozen, raw tuna in June. And another outbreak that month was linked to frozen, pre-packaged chicken entrees.

How common are salmonella outbreaks in Minnesota?

Pretty common. Each year, about 700 infections are confirmed in the state, but that's likely a small fraction of the total number of people who get sick from eating food contaminated with the bacteria.

Among food-borne disease experts, there is a general consensus that for every case of salmonella reported in the United States, 29 cases go unreported. So, by that measure, we could have 21,000 cases of salmonella in Minnesota each year.

What is salmonella and how do we become exposed to it?

It's a bacterium that lives in the intestinal tract of humans, birds and other animals. So, most of the time, animal feces is the culprit. It can get in the food supply if fruits or vegetables are washed or irrigated in the field with contaminated water. In the case of raw meat, contamination is often spread during the slaughtering process. And with raw eggs, they can become contaminated if the laying chicken is already infected with the bacteria.

What can people do to minimize their exposure to salmonella?

It's challenging if you're eating at a restaurant because you don't know how the food was prepared. There are standards for cooking meat thoroughly and for keeping work surfaces separate to avoid cross-contamination. But raw fruits and vegetables present a problem; it's hard to decontaminate a product if you can't cook it.

If you're preparing food at home, you have better control over the cooking process. You can use a thermometer to make sure that your meat is cooked properly. Same with eggs — you can completely cook the yolk. But again, with raw fruits and vegetables, it's hard to eliminate salmonella.

Food irradiation is one technique that kills the bacteria. However, that technology hasn't been popular with the U.S. public. It is used to treat imported spices and some fruits, such as mangoes and papayas.

What food safety efforts are happening at the farm or manufacturing level?

The FDA issued a new rule Thursday requiring manufacturers to prevent food contamination, rather than just respond to it. They will have to create food safety plans that show how they handle and process food and monitor for dangerous bacteria.

Next month, the government is expected to issue another rule requiring farmers to do the same. They'll be expected to make sure that their irrigation water is clean and that workers wash their hands and keep animals out of produce fields.

More FDA inspections are also in the works.