By Katia Hetter, CNN

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As a salmonella outbreak linked to eggs has sickened 79 people across seven states as of June 5, a California-based company has recalled 1.7 million dozen eggs because of potential contamination, according to the US Food and Drug Administration.

This rash of illnesses follows a separate outbreak of salmonella infections tied to recalled cucumbers and the US Department of Agriculture’s Food Safety and Inspection Service issuing a public health alert for raw ground beef products that could be contaminated with E. coli.

As summer approaches, I wanted to understand more about these foodborne infections. What are common causes and symptoms? What are possible consequences of salmonella and E. coli infections? Why are foodborne infections more common in the summer, and what are food safety practices that everyone should follow?

To help me with these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct clinical associate professor at George Washington University. She previously served as health commissioner of Baltimore, where her responsibilities included overseeing food safety.

CNN: What are the most common causes of foodborne infections? What symptoms do people experience?

Dr. Leana Wen: Foodborne infections are caused by pathogens, including viruses, bacteria and parasites.

Norovirus is the leading cause of foodborne illness in the United States. The virus is implicated in about half of all food-related illnesses, according to the US Centers for Disease Control and Prevention. The pathogen can spread through contaminated food and drink or from person to person when someone touches objects that have been handled by an infected individual and then touches their mouth, or through sharing cups, bowls and utensils.

A number of bacteria can also cause foodborne illness. Infections can occur from eating raw or undercooked food. Other illnesses occur due to bacterial contamination in food. Common bacteria implicated in foodborne illness include campylobacter, listeria, salmonella and E. coli.

Symptoms of foodborne infections include nausea, vomiting, diarrhea and abdominal cramping. Depending on the cause and on the health of the individual, other symptoms may develop such as fevers, bloody diarrhea and dehydration that worsens underlying health problems.

CNN: What are possible consequences of salmonella and E. coli infections? How are they treated?

Wen: Salmonella most often spreads to people through contaminated food. While most people who fall ill recover quickly with no long-term consequences, some can become very ill. In the current outbreak involving the California-based egg distributor, 21 people have been hospitalized out of the 79 people sickened, according to the CDC.

The key to treatment is hydration. Individuals with diarrhea should keep up fluid intake to prevent dehydration. Those who are vomiting and unable to keep fluids down may need to take anti-nausea medications. Most people will get better without using antibiotics, but they may be needed for individuals at risk of severe illness.

E. coli lives in the intestines of humans and many animals. A specific type of E. coli is known to cause a serious infection. This strain, called O157:H7, produces a toxin that can damage the intestinal wall and lead to bloody diarrhea. This is the strain implicated in the recent ground beef recall. The specific danger of O157:H7 is that some people who fall ill from it could develop a complication called hemolytic uremic syndrome, or HUS. This syndrome can lead to permanent health problems such as kidney failure, and in some cases, it is fatal.

Individuals who develop an O157:H7 infection should also drink plenty of fluids to prevent dehydration from diarrhea. Antibiotics are specifically not given for these infections because they may increase the risk of developing HUS.

Most foodborne infections can be treated at home. Reasons to contact your doctor include inability to keep down fluids, persistent diarrhea over three days, high fevers and bloody stools. Babies, older people and individuals with chronic medical conditions should have a lower threshold for seeking help.

CNN: Why are foodborne infections more common in the summer?

Wen: The risk of foodborne illness is higher during summer months because bacteria grow more quickly in warmer weather. In addition, people are more likely to have barbecues and outdoor events that involve food. Inadequate preparation or leaving out food for too long can lead to foodborne illnesses.

CNN: What are food safety practices that everyone should follow?

Wen: It’s important to abide by recall notices. If you have purchased a product that is now recalled, do not consume it. Follow other instructions as directed by health authorities. Keep an eye on not only federal advisories but your local health department, which will inform you of possible foodborne illnesses associated with local stores and restaurants.

Follow best practices in food preparation. That includes washing produce such as vegetables and fruits, even if they end up getting peeled. Make sure to cook meat and fish to the recommended temperature. Be aware of what utensils and plates you are using with raw meat and fish, and don’t use them for other food items.

Remember that bacteria multiply quickly at room temperature. Two hours is the limit for leaving food out before throwing it away or storing it in a refrigerator or freezer. If you are outdoors and the ambient temperature is very warm, reduce the limit to one hour.

It’s also a good idea to avoid unpasteurized or “raw” milk and uncooked eggs. Of course, be sure to wash your hands often and well with soap and water. People who have diarrhea, vomiting and stomach cramps should not prepare food. Those most vulnerable to severe illness, including older adults, babies, and those who are pregnant or have serious underlying conditions, should be especially careful of foodborne illness as they are of other infections.

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