Recently, outbreaks of E. coli, listeria, and salmonella have been in the news for causing illness among Americans. So what are these harmful bacteria?

Identifying these bacteria can be challenging without specialized tools and knowledge in microbiology.

Health authorities are closely monitoring outbreaks to protect public health. In the past few months, numerous consumers became sick from E. coli after eating McDonald’s Quarter Pounders, resulting in one death; meanwhile, 59 people were hospitalized and 10 died due to a listeria outbreak tied to deli meats; in addition, 93 individuals in multiple states were infected with salmonella from eggs.

It’s crucial to understand that food recalls and safety warnings, while alarming, are quite common. You can find updates on such incidents via the Food and Drug Administration’s list.

Here are the important details regarding the bacteria involved in these recent food recalls:

Understanding the Bacteria

E. coli: Various strains of Escherichia coli, or E. coli, exist in food, water, and the intestines of humans and animals, according to the U.S. Centers for Disease Control and Prevention (CDC). This bacteria is often spread through food or water that has been tainted with fecal matter from humans or animals.

Some E. coli types can cause illness, with Shiga toxin-producing E. coli being the most prevalent form associated with disease.

Listeria: Listeria infections come from contaminated food and it ranks as the third leading cause of fatalities from foodborne illnesses in the U.S., according to the CDC.

What makes listeria distinct is its ability to thrive in cold, wet environments, meaning it can grow even in refrigerated conditions, as stated by the U.S. Department of Agriculture.

Salmonella: This bacteria is a leading cause of foodborne illness-related deaths.

Salmonella can be found in the digestive tracts of humans and animals. Out of more than 2,500 known salmonella types, less than 100 typically lead to illness. Infection occurs through consuming contaminated food or drink, contact with contaminated water, or interacting with feces, animals, or their living environments.

What Are the Symptoms?

E. coli: Symptoms generally develop three to four days after ingestion of contaminated food or water. The strain linked to the McDonald’s outbreak, the Shiga toxin-producing type, can cause severe abdominal pain, diarrhea often mixed with blood, and vomiting. In some cases, individuals may experience serious kidney complications requiring medical attention.

Listeria: There are two categories of listeria-related illnesses: intestinal and invasive.

Intestinal listeria is often misdiagnosed since tests for it aren’t commonly conducted in labs, according to the CDC. Symptoms such as diarrhea and vomiting can surface within a day after eating contaminated food and last for up to three days. While intestinal symptoms may be mild, invasive listeria infections can occur, leading to more severe complications starting about two weeks after ingestion.

Those not pregnant may experience fever, body aches, fatigue resembling flu symptoms, headaches, a stiff neck, confusion, balance issues, and seizures, with an approximate one-in-six mortality rate for invasive cases.

Pregnant individuals may experience mild flu-like symptoms. However, severe cases of invasive listeria during pregnancy can result in miscarriage, stillbirth, premature delivery, or life-threatening infections for newborns, according to the CDC.

Salmonella: Symptoms typically emerge between six hours and six days after exposure. Most individuals report abdominal cramps and watery diarrhea, which may contain blood or mucus, along with potential headaches, nausea, vomiting, and loss of appetite. Recovery usually occurs without medical intervention within four to seven days.

However, certain groups—children under five, adults over 65, and those with weakened immune systems—face heightened risks for severe illness that may necessitate hospitalization.

Seek medical help if you experience prolonged diarrhea or vomiting lasting over two days, bloody stool or urine, a fever exceeding 102 degrees, signs of dehydration, or any long-term complications.

Preventing Foodborne Illness

Consumers can take straightforward measures to minimize their risk of illness. First, stay informed about food safety notifications and recalls.

Washing your hands with warm, soapy water regularly—before and after meal prep or after handling animals or potentially contaminated items like diapers—can significantly reduce your risk, as advised by the USDA. Additionally, make sure to clean and thoroughly sanitize areas or items that have come into contact with raw food or waste. Also, avoid cross-contaminating food and surfaces.

It is also important to note that salmonella thrives in warmer conditions. Therefore, refrigerate or freeze perishable items, prepared meals, and leftovers within two hours, or sooner if temperatures are high outdoors.

The FDA has indicated that Listeria can grow in refrigerators. To minimize the risk, keep refrigerator temperatures at 40°F (4°C) or lower, while freezers should be set to 0°F (-18°C). It’s important to consume ready-to-eat refrigerated foods before the “Use By” date printed on their packaging, as the chances of listeria growth increase the longer these foods are stored in the fridge. Regular cleaning of refrigerators is also essential for safety.