HelloFresh ground beef may be contaminated with E. coli. Here’s what you need to know.

Ground beef shipped out to customers in HelloFresh meal kits over the summer could be contaminated with E. coli, according to a public health alert issued on the weekend by the U.S. Department of Agriculture's Food Safety and Inspection Service.

The meal kits in question were shipped to customers between July 2 and July 21 and are no longer available for purchase, but officials are concerned the product might still be in people’s freezers.

The affected ground beef is described as 10-ounce plastic vacuum-packed packages containing 85% lean ground beef, with the following codes on the side of the packaging: “EST#46841 L1 22 155” or “EST#46841 L5 22 155.” The agency noted that the packages also show the code “EST.46841” inside the USDA mark of inspection.

In the alert, issued Saturday, the FSIS said it was working with the Centers for Disease Control and Prevention, as well as state public health partners, on investigating a larger outbreak of E. coli O157:H7, a strain of E. coli that can cause severe illness. During that investigation, the FSIS said it discovered that multiple consumers who were affected by the E. coli outbreak had consumed the raw ground beef.

The CDC had been investigating an E. coli outbreak since August. According to the agency, it seems to have originated in the Midwest and it has affected six states, including New York, Kentucky, Indiana, Michigan, Ohio and Pennsylvania.

Although the agency's website still says that the food source causing the outbreak is unknown, earlier this month, the CDC said that a lettuce sandwich served at the fast-food chain Wendy's was a possible source. As a precautionary measure, the company immediately removed the lettuce at restaurants in four states.

Per the latest data, which has not been updated since Sept. 1, 97 cases have been reported to the CDC, but the agency said on its website that the true number of people who have been infected with the bacteria is likely higher and may include other states that have not yet reported cases.

Yahoo News spoke to Catherine Troisi, an infectious disease epidemiologist at the University of Texas School of Public Health in Houston, on questions that people may have about E. coli and how people can avoid getting sick.

What is E. coli?

Formally known as Escherichia coli, E. coli are bacteria that normally live in the intestines of people and animals. In humans, the bacteria actually play an important role in keeping the digestive system healthy.

“E. coli is around all the time,” Troisi said, adding that most strains are harmless and don’t cause disease. However, some are pathogenic and can cause severe illness and even death in some circumstances, she said. One of these is a type called Shiga toxin-producing E. coli (STEC).

The most commonly identified STEC in North America is E. coli O157:H7. This is the type driving the most recent U.S. outbreak and the one connected to the HelloFresh ground beef. It is also one “most commonly” connected to food-borne outbreaks, according to the CDC.

How do these infections spread, and how can you prevent getting sick?

Troisi said humans can get it from contaminated cattle feces or from humans infected with E. coli. This typically happens when coming into contact with trace amounts of feces, which are usually invisible.

“This is a food-borne or water-borne pathogen, so you can get it from water that's contaminated, or you can get it from food, either meat that has not been cooked to a proper temperature, or it's pretty common with things like lettuce and spinach — things that we don't cook all the time and so the bacteria isn't killed,” Troisi said.

People can also get infected by swallowing contaminated water from pools or a lake while swimming. They can also get sick eating food prepared by infected people who did not wash their hands before making the meal.

Troisi said that the best way to avoid getting sick with E. coli O157:H7 is by cooking meat thoroughly. Washing hands after using the bathroom, before eating or preparing food, and after you’ve had any contact with animals or visited a farm where you can be exposed to animal feces, are also good ways to prevent illness.

In addition, certain foods that are unpasteurized, such as raw milk, apple juice and soft cheeses made from raw milk should be avoided, as they carry a high risk of infection with E. coli O157:H7, Troisi said.

Are these E. coli outbreaks common? What is unique about the recent outbreak?

Troisi told Yahoo News that food-borne E. coli outbreaks are very common. According to the CDC, an estimated 265,000 STEC infections occur each year in the United States. This number, however, is likely to be higher because not all STEC infections are diagnosed, for several reasons — including the fact that some people recover without needing medical care and are often not tested for it.

From 2017 to 2020, the CDC estimates that multistate outbreaks linked to contaminated food have caused 7,659 illnesses, 2,044 hospitalizations and 41 deaths.

The reason why any outbreak of E. coli O157:H7 is relevant, Troisi said, is because this strain “can lead to a condition called hemolytic uremic syndrome (HUS), which can kill.”

Symptoms of HUS include fever, extreme fatigue, abdominal pain, shortness of breath, decreased urination, small unexplained bruises or bleeding, and pallor.

The latest CDC data shows that in the most recent outbreak, 43 people have been hospitalized and 10 developed HUS, but no deaths have been reported. However, the epidemiologist said that “given this burden of disease, we all need to be aware of how to prevent infections in our homes and where to avoid eating when there are concerns about outbreaks at commercial establishments.”

What are the symptoms and when to seek medical care?

Troisi explained that it usually takes about four to five days after you’ve ingested the infected food or water to develop symptoms, and that some people do not develop symptoms.

Symptoms vary from person to person but can include high fever, vomiting and diarrhea, which is often bloody, Troisi said. “They'll have severe stomach cramping, and it can lead to serious kidney failure,” she explained.

Most people recover in a few days, but in some cases people have died, usually from kidney failure, Troisi said.

Those who are more likely to develop severe illness and hemolytic uremic syndrome (HUS) are very young children and the elderly, according to the CDC.

There are no specific treatments to treat people sickened with E. coli O157:H7, and antibiotics, Troisi said, are not effective. In fact, she said, there’s some evidence that taking them may increase the risk of HUS. Antidiarrheal medicines like Imodium may also increase that risk, according to the CDC.

Finally, for those who do get infected with E. coli O157:H7, staying hydrated is key, the epidemiologist said.

Signs of dehydration can include urinating less frequently than usual, dry mouth and throat, as well as feeling dizzy when standing up.

“If there are issues with hydration … that's when you should consider calling your health care provider, because it may be that you need intravenous fluids,” Troisi said.