Raw milk cheese is tied to E. coli outbreak: What to know, according to a doctor

By Katia Hetter, CNN

(CNN) — Federal health officials are investigating a multistate outbreak of an especially dangerous type of E. coli infection linked to raw cheddar cheese, according to an alert from the US Food and Drug Administration. Nine people have become ill and three have been hospitalized, prompting food safety experts to renew warnings about the risks associated with raw milk and cheeses made from it.

At the same time, a growing number of consumers are seeking out raw milk for perceived health benefits, despite longstanding warnings from public health authorities about its safety.

The tension is rising about whether raw milk is safe, who should be especially careful and what consumers should know when choosing dairy products. To help make sense of it all, I spoke with CNN wellness expert Dr. Leana Wen, an emergency physician and clinical associate professor at George Washington University. She previously served as Baltimore’s health commissioner.

CNN: What is this type of E. coli, and why is it particularly problematic?

Dr. Leana Wen: E. coli refers to a very common group of bacteria, many of which live harmlessly in people’s intestines. Certain strains can cause severe disease. One of the most concerning is E. coli O157:H7, which produces a toxin that can damage the lining of the intestines. People may develop severe abdominal cramps and diarrhea that is often bloody. In some patients, infection from this strain can lead to a complication called hemolytic uremic syndrome, which can cause kidney failure and death. This complication can occur in people of any age but is especially common in children between 6 months and 4 years old.

CNN: What is known about this current outbreak?

Wen: According to the FDA, this outbreak has been linked to raw, or unpasteurized, cheddar cheese. From September 2025 to February 2026, nine people were infected with E. coli O157:H7 after consuming raw milk cheddar made by a company in California. Three people have been hospitalized, and one of them developed hemolytic uremic syndrome. Over half of the illnesses were in children younger than 5.

The epidemiological investigation links the illnesses to consuming a specific brand of raw milk cheddar cheese. The FDA alert states that the agency has recommended that the producer voluntarily remove the product from the market, and the firm has declined.

Situations like this are not new. Raw milk and products made from it have been associated with outbreaks of multiple type of bacteria, including E. coli, salmonella, campylobacter and listeria. What we are seeing in this situation is a reminder that these products can carry real risks.

CNN: How do people become infected with E. coli from unpasteurized dairy products?

Wen: The source of infection is typically contamination. E. coli and other bacteria are present in the intestines of healthy cattle and in the environment. During milking and processing, bacteria can enter the milk if strict hygiene measures are not maintained.

Pasteurization is the process designed to eliminate these pathogens. When milk is not pasteurized, any bacteria present can remain in the final product. Even careful farming practices cannot eliminate the risk, because contamination can occur at multiple points during production. For example, milk can be contaminated by manure or environmental filth, infections of the udder such as mastitis or from surfaces during the milking process. There can also be contamination from improperly cleaned equipment or accidental cross contamination by humans handling the milk.

CNN: How does pasteurization reduce risk, and what does it actually do?

Wen: Pasteurization is a process that heats milk to a specific temperature for a set period and then cools it rapidly. The most common method in the United States heats milk to at least 161 degrees Fahrenheit (nearly 72 degrees C) for at least 15 seconds before cooling it back to its original temperature. These steps are designed to kill harmful bacteria while preserving the nutritional value of the milk.

The process is named after Louis Pasteur, the 19th century French scientist who demonstrated that heat could be used to kill microorganisms that cause disease and spoilage. His work laid the foundation for modern food safety practices.

Pasteurization has been one of the most effective public health interventions in reducing foodborne illness. Before it became widespread, milk was a major source of infection, with some estimates showing that as many as 1 in 4 cases of foodborne illness were linked to contaminated milk.

CNN: Is raw milk or raw milk cheese safe to consume? Who is most at risk from consuming raw milk products?

Wen: In my view, the answer is no — it is not safe to consume. Raw milk and its products carry the risk of harmful bacterial contamination as has been borne out in numerous outbreak investigations such as the current one.

Anyone can become ill from contaminated raw milk, but certain groups are more likely to develop severe disease. These categories include young children, older adults, pregnant women and people with weakened immune systems. Because of these risks, public health agencies strongly advise that individuals in these groups avoid raw milk and products made from it.

CNN: Some people claim raw milk has health benefits. What does the evidence show?

Wen: Claims about the health benefits of raw milk often center on ideas that it contains beneficial bacteria, supports the immune system and can cure a variety of diseases including asthma and autoimmune illnesses. These claims are not backed by scientific evidence.

It is not at all clear that raw milk provides health advantages over pasteurized milk. At the same time, consistent evidence exists that consuming raw milk products increases the risk of serious infections.

CNN: What is the key takeaway for consumers in light of this latest outbreak?

Wen: The main takeaway should be that raw milk and products made from it can carry dangerous bacteria, and that choosing pasteurized dairy products is a simple and effective way to reduce risk.

In addition, consumers should also pay attention to outbreak alerts and avoid products that have been linked to illness. If someone develops symptoms such as severe abdominal pain, high fevers or bloody diarrhea after consuming a high-risk food, they should seek medical care.

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