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An outbreak of infections linked to McDonald’s Quarter Pounders has many people in the United States concerned about their exposure to dangerous E. coli bacteria.

It is not yet known which specific food ingredient in the burgers was contaminated, but as of Tuesday, dozens of people in at least 10 states have fallen ill with E. coli infections, including one death, according to the U.S. Centers for Disease. Control and prevention.

The type of bacteria involved in this outbreak is E. coli O157:H7.

“With this particular type of E coli that has been in the news — it’s called O157:H7 — the most vulnerable groups tend to be older adults and very young children,” said Dr. James Gaensbauer, an infectious disease pediatrician at Mayo Clinic. Children’s Center in Rochester, Minnesota.

Although E. coli is very common and can cause a number of health problems, including urinary tract infections and stomach flu, “this particular strain mainly causes gastrointestinal complaints, including abdominal cramps, vomiting and especially painful diarrhea that can sometimes become bloody.” Dr. Marcus Pereira, an assistant clinical professor of medicine at Columbia University College of Physicians, said in an email.

“Some people can also develop a fever and end up becoming dehydrated because they don’t eat or drink much while they have diarrhea,” he said. “The good news is that although it can sometimes be serious, most people with E. coli O157:H7 recover on their own.”

McDonald’s customers are encouraged to seek medical care if they have eaten a Quarter Pounder and developed symptoms of an E. coli infection.

What are the symptoms and how is it treated?

E. coli, or Escherichia coli, is a common type of bacteria that lives in the intestines of people and animals, but some E. coli can make people sick. People can become infected after ingesting E. coli through contaminated food or water or through contact with animals, environments, or other people where the bacteria are present.

“It also occurs in clusters that may involve some exposure or some risk, and that might happen maybe every few years,” Gaensbauer says. “It’s relatively common and something I probably deal with a few times a year.”

According to the U.S. Food and Drug Administration, people infected with the harmful E. coli may begin to notice symptoms several days to as long as nine days after exposure to the bacteria. A person can be tested for the presence of E. coli in the stool.

Symptoms of infection include diarrhea, especially that lasting more than three days, and fever higher than 102 degrees Fahrenheit. Some people may also experience severe stomach cramps and vomiting.

Most healthy people may not develop symptoms, Gaensbauer said.

But “the symptoms people should look out for are, for the most part, diarrhea,” he said. “The severe forms of diarrhea caused by E. coli can often start with loose stools, a watery form of diarrhea, but can then occasionally progress to bloody diarrhea.”

Most people recover after about a week without treatment, but some may develop serious health problems and require hospitalization.

“There is a particular type of E. coli, known as Shiga toxin-producing E. coli, or STEC, that has been implicated in serious outbreaks of foodborne illness. Exposed individuals may develop bloody diarrhea and even kidney failure,” said Dr. Leana Wen, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health, last year.

The CDC estimates that approximately 265,000 infections with Shiga toxin-producing E. coli occur annually in the United States.

“Treatment consists of supportive care for symptoms and fluids for hydration,” Wen added.

Infection with STEC can lead to a serious health condition called hemolytic uremic syndrome, which can lead to kidney failure or even death. And O157:H7 is one of these types of bacteria.

“For the initial stages of an E coli infection, where diarrhea occurs, hydration is the most important treatment, so infected individuals should drink enough fluids if they can tolerate it. Children are at the greatest risk for dehydration and products such as Pedialyte are often recommended in this situation,” Pereira wrote in the email.

“Sometimes patients need IV hydration in a medical facility if they are more severely dehydrated. For E. coli O157:H7, antibiotics are controversial and generally not recommended based on any evidence that they may actually increase the risk of hemolytic uremic syndrome,” he said.

For this reason, the CDC warns against the use of antibiotics for STEC infections.

“The other thing we’re very careful about here is that sometimes there are medications that people take to slow down their bowels when they have diarrhea, and those medications are not recommended,” Gaensbauer said. “The idea is that you might not want to keep the bacteria and poison down – maybe it’s better to have diarrhea. So people should always consult their doctor before taking anti-diarrheal medications if they are concerned that they have an E. coli infection.”

The best ways to prevent E. coli infections are to keep your hands clean by washing them regularly, preparing safe foods and drinking safe water, according to the CDC.

“Undercooking meat is a common and serious problem. Infectious organisms may not be killed at lower temperatures,” Wen said. Thoroughly cooking meat to an internal temperature of 160 degrees Fahrenheit kills E. coli O157:H7, according to the U.S. Department of Agriculture.

Another way to prevent diseases is to wash fruits and vegetables thoroughly before using them.

“Even if you are going to peel them, you must first wash them under running water. It is not necessary or advisable to use soap, detergent, disinfectants or other solutions,” Wen said.

“Be aware of which containers and utensils come into contact with raw meat. Do not put salads or cooked meats in these containers,” she said. “Also, don’t wash other uncooked meat or raw seafood in the sink. That could spread bacteria, and you could unintentionally contaminate other food.”

The CDC also notes that choosing pasteurized milk and juices can reduce the risk of exposure to E. coli because the pasteurization process kills harmful germs, including E. coli.