McDonald’s E. coli outbreak – which has now sickened more than 100 people per reports – has drawn attention to the risk of food borne diseases.

The E. coli infections were linked to contaminated onions served on McDonald’s Quarter Pounder hamburgers, according to the US Centers for Disease and Prevention (CDC), which continues to investigate the outbreak.

Many other foods could potentially transmit dangerous bacteria if stored or prepared unsafely, experts say, with an estimated 48 million people (one in six) affected each year, according to the CDC.

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Fox News Digital spoke with food safety experts about some of the most common foodborne illnesses and how to prevent them.

1. E.coli

E. coli – officially known as Escherichia coli – is one type of bacteria found in the environment, food and intestines of humans and animals, according to the CDC.

E. coli – officially known as Escherichia coli – is a type of bacteria found in the environment, food and intestines of humans and animals. (iStock)

The bacterium can be spread through contaminated food or water or contact with animals, environments or other people, the same source said.

Eating meat that hasn’t been cooked enough to kill E. coli can cause infection, according to Mitzi D. Baum, CEO of Stop Foodborne Illness in Chicago.

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“Other known sources of infection include consumption of sprouts, lettuce, salami, unpasteurized milk (and milk products) and unpasteurized juice, and swimming in or drinking sewage contaminated water“, she told Fox News Digital.

“Bacteria in the diarrheal stools of infected people can be transmitted from one person to another if hygiene or hand-washing habits are inadequate,” Baum added.

Symptoms and treatment

Symptoms of E. coli disease include – but are not limited to – severe stomach cramps, diarrhea (often bloody), vomiting, respiratory diseaseurinary tract infections, fever and pneumonia, according to the CDC.

E. coli can become “dangerous or fatal” in very young people, older adults and those with compromised immune systems, who can develop a condition called hemolytic uremic syndrome (HUS), according to Baum.

Symptoms of E. coli disease can include severe stomach cramps, diarrhea (often bloody), vomiting, respiratory illness, urinary tract infections, fever, and pneumonia. (iStock)

Symptoms of HUS can include fever, abdominal pain, pale skin tone, fatigue, irritability, decreased urination, swelling and small, unexplained bruising or bleeding from the nose and mouth, the expert added.

“Nonspecific supportive therapy, including hydration, is important,” Baum said.

E. coli can become “dangerous or fatal” in very young people, older adults and those with compromised immune systems.

“There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of HUS.”

Treatment often consists of supportive careBaum said, with close monitoring of renal (kidney) function, hemoglobin and platelet counts.

2. Listeria

Listeria is the third leading cause of death food borne illness in the country, according to the CDC.

The bacterium is known to spread easily in delicatessens and in environments where food is prepared.

The listeria bacteria is known to spread easily in delicatessens and in environments where food is prepared. (iStock)

“The bacterium has been found in a variety of raw foods, such as raw meat and vegetables, as well as in foods that become contaminated after cooking or processing, such as soft cheeses, smoked seafood, and processed meats such as hot dogs and deli meats,” Baum said.

“Unpasteurized (raw) milk and cheeses and other foods made from unpasteurized milk are particularly likely to contain the bacteria.”

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Listeria is killed by pasteurization and cooking, Baum noted, but some prepared foods can become contaminated before they are packaged.

“Unlike most bacteria, Listeria can grow and multiply in certain foods in the refrigerator,” she warned.

Symptoms and treatment

The most common symptoms of listeria infection include fever, fatigue and muscle aches, according to the CDC.

“Someone with listeriosis usually has a fever and muscle aches, which are sometimes preceded by diarrhea or other things gastrointestinal symptomsBaum said.

“Almost everyone diagnosed with listeriosis has an ‘invasive’ infection where the bacteria spreads outside the gastrointestinal tract.”

Listeria is the third leading cause of death from foodborne illness in the country, according to the CDC. (BSIP/UIG via Getty Images)

Some people also experience a stiff neck, headaches, balance problems, seizures or disorientation.

Listeriosis is treated with antibiotics.

“A person in a high-risk category who experiences fever and other nonspecific symptoms, such as fatigue and aches, within two months of eating contaminated food should seek medical attention,” Baum advised.

3. Norovirus

Norovirus is a highly contagious virus that causes inflammation of the stomach or intestines, according to the CDC.

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“Norovirus, also known as Norwalk-like virus, is a leading cause of gastroenteritis in the United States,” Dr. Amber Charoen, a board-certified gastroenterologist with Gastro Health in Kennewick, Washington, told Fox News Digital.

“It can be spread with as few as 10 particles through contaminated food, vomit, feces and even person to person contact.”

Symptoms and treatment

Although often referred to as a “stomach flu” or “stomach bug,” it is not norovirus related to influenza.

“The symptoms of norovirus vary, but those infected tend to have a mix of low-grade fever, chills, vomiting, headache, muscle aches and fatigue,” Baum said.

Norovirus is a highly contagious virus that causes inflammation of the stomach or intestines, according to the CDC. (iStock)

“In addition, outbreaks of norovirus usually cause nausea (more often in children), watery diarrhea (more common in adults) and stomach cramps.”

There is no specific medication to treat norovirus, according to Baum.

“If you have norovirus illness, drink plenty of fluids to replace fluids lost from vomiting and diarrhea,” she advised.

4. Salmonella

Salmonella is a bacteria that is often linked to poultry, eggs, dairy products and other foods such as fresh produce, meat and nuts, according to Charoen.

Infections can be caused by consuming contaminated chicken, pork, fruit, seed vegetables, other produce, beef and turkey, the CDC states on its website. Bacteria can spread to other foods through cross-contamination.

Salmonella is a bacteria that is often linked to poultry, eggs, dairy products and other foods such as fresh produce, meat and nuts. (iStock)

Symptoms and treatment

Most people who are infected get diarrhea, stomach cramps and fever, according to the CDC. Headache, vomiting and nausea may also occur.

Most patients notice symptoms within six hours to six days of being infected, and they usually last four to seven days.

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“Most people recover without specific treatment,” Baum said. “Antibiotics are usually only used to treat people with severe disease.”

Patients should drink extra fluids as long as diarrhea persists, she advised.

5. Campylobacter

Campylobacteriosis is a bacteria most often associated with eating raw or undercooked poultry or from cross-contamination of other foods by these items, according to Baum.

Campylobacteriosis is a bacteria most often associated with eating raw or undercooked poultry or from cross-contamination of other foods. (iStock)

“Many chicken flocks are infected with Campylobacter but show no signs of disease,” she noted.

“Campylobacter can easily spread from bird to bird through a common water source or through contact with infected feces.”

Symptoms and treatment

Typical symptoms of Campylobacteriosis disease include diarrhea, cramps, abdominal pain and fever.

“Diarrhea caused by this infection can be either watery or bloody, depending on which area of ​​the intestines is affected, and usually begins two to five days after exposure,” says Charoen.

In addition to gastrointestinal symptoms, Campylobacter infection has also been linked to long-term problems such as reactive arthritis and Guillain-Barré syndrome, which can affect the joints and nervous system, Charoen added.

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Almost all people infected with Campylobacter recover without any specific treatment, according to Baum.

“Patients should drink extra fluids for the duration of the diarrhea,” she advised.

“In more severe cases, antibiotics such as azithromycin or erythromycin can shorten the duration of symptoms if given early in the disease.”

Typical symptoms of Campylobacteriosis disease include diarrhea, cramps, abdominal pain and fever. (iStock)

In addition to the five listed above, there are other bacteria that can cause foodborne illness.

These include Staphylococcus aureus (Staph), Clostridium perfringens, toxoplasma and others.

Preventing foodborne illnesses

Dr. Benjamin Barlow, an emergency physician and Chief Medical Officer of American Family Care – a provider of urgent care, accessible primary care and occupational medicine in Alabama – provided the following guidance to prevent food contamination.

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“You can prevent foodborne illness by washing your hands after touching any animal or their food, or being in their environment,” Barlow, former senior The White House physician to Presidents Obama and Trump, told Fox News Digital.

“Avoid eating poorly cooked foods such as minced meat, poultry or eggs and raw/unpasteurized milk, including cheeses made with it,” he added.

Experts say to wash all fruits and vegetables before cooking and to keep raw meat separate from other foods. (iStock)

Before you start food preparation, wash your hands for 20 seconds with soap and water, advises Barlow.

“Also wash your hands between touching raw meat and other foods before eating,” he said. “If you can, wear gloves when cooking.”

It is also best practice to wash all fruits and vegetables before cooking and to keep raw meat separate from other foods.

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When cooking, use a thermometer to make sure it reaches the safe minimum internal temperature, Barlow stressed.

Safe temperatures are 165°F for chicken and 145°F for beef, pork and seafood.

Safe temperatures are 165°F for chicken and 145°F for beef, pork and seafood.

It’s also important to check expiration dates and discard expired items, experts agree.

“Make sure food is chilled within two hours of cooking – this is especially important as we head into the off season holiday parties“, Barlow said.

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“In the summer heat, food should be cooled after an hour.”

Anyone experiencing any gastrointestinal symptoms, such as diarrhea or vomiting, should not prepare any food to avoid transmitting the bacteria or virus, the doctor added.