Types of Germs That Cause Food Poisoning
Food poisoning is a general term for gastrointestinal illness linked to consuming contaminated food or drinks, but it can be caused by a number of germs.
Salmonella
Most people are familiar with the term salmonella, but they may not know that there are more than 2,000 types of the bug. It’s usually associated with animal products like chicken, eggs, and milk, but raw vegetables and even water can carry salmonella, too.
Salmonella is usually introduced to foods at a processing plant or when the foods are handled. It’s a common diagnosis of infectious diarrhea in the United States.
“Symptoms of salmonellosis vary from a mild gastroenteritis [stomach and intestinal inflammation] to more severe and prolonged diarrhea,” says Kristina D. Mena, PhD, the El Paso dean for the UTHealth Houston School of Public Health.
E. Coli
While most E. coli is harmless and part of a healthy gut, this bacteria can sometimes cause infections like pneumonia and gastrointestinal illness. In the past, E. coli infections were commonly associated with undercooked ground beef, but the germ can show up in other places, as well.
“Outbreaks of E. coli have involved a wide variety of food, including fresh produce, beef, nuts, water, and cookie dough, to name a few,” Dr. Mena says. Symptoms can include nausea and vomiting, watery diarrhea, or sometimes bloody diarrhea, depending on the E. coli type.
Cyclosporiasis
Cyclosporiasis, an infection caused by the cyclospora parasite, isn’t typically life-threatening. However, it can cause severe diarrhea that may start from two days to two weeks after infection. Symptoms often resolve on their own in days but may persist or come and go for over a month.
Outbreaks in the United States have been linked to fresh produce, including leafy vegetables and berries. Mena notes that water is often cited as a way this parasite impacts food, but she says this refers to water used in crop irrigation. It doesn’t refer to tap water, which is treated at a drinking water treatment facility.
Campylobacter
It’s not as well known as salmonella and E. coli, but campylobacter can be pretty nasty in its own right. “Campylobacter is identified more often than any other causative agent of gastroenteritis in the United States and Europe,” Mena says. This bacteria may also cause high fever, arthritis, and Guillain-Barré syndrome (a severe, progressive muscle weakness, she says. “Most often, infections and subsequent illnesses result from the consumption of contaminated poultry or poultry products,” Mena says.
Shigella
Though meat is commonly thought of as the transmitter of food poisoning germs, shigella can be passed along via vegetables, often related to breakdowns in food safety. “Transmission is most often associated with infected food handlers who pass the bacteria from person to person due to poor hygiene practices,” Mena says. “It has also been suggested that flies may have a role in its transmission.”
Symptoms typically include abdominal cramps and bloody stool. This infection can also cause fevers and tenesmus, which is the feeling that you need to pass stool, even though your bowels are already empty.
Listeria
Listeria outbreaks in the United States have been linked to produce; raw, unpasteurized milk and cheese; ice cream; and raw or undercooked poultry and seafood. Similar to other foodborne illnesses, a listeria infection can cause diarrhea and fever. These infections can be especially dangerous for certain people. For those with compromised immune systems, listeria infection could lead to bloodstream infections or meningitis, and for pregnant people, it could lead to stillbirth, miscarriage, premature birth, or life-threatening infection in the newborn.
Botulism
Although rare, botulism is one of the most serious causes of food poisoning; it is most commonly associated with improperly canned vegetables and cured pork and ham.
“This bacterium produces a neurotoxin that results in paralysis,” Mena says. “Besides paralysis, symptoms may include body aches, nausea, vomiting, weakness, and an inability to swallow. People who are not treated immediately have a much higher chance of dying.”
Enteric Viruses
Enteric, or intestinal, viruses like norovirus and hepatitis A are tied to an increasing number of food poisoning outbreaks, Mena says. “Noroviruses are the viruses that have been implicated in the string of cruise ship outbreaks,” she says. “Besides diarrhea, people also typically experience vomiting. Norovirus outbreaks have been associated with a variety of food, including shellfish.”
Hepatitis A outbreaks can typically be traced back to poor food safety during food handling. “Hepatitis A infections may result in nausea, malaise, and jaundice, with the more severe illnesses occurring in older individuals,” Mena says.
Staphylococcus Aureus
Staphylococcal food poisoning is caused by eating foods contaminated with toxins produced by the bacterium Staphylococcus aureus. Food handlers carrying the bacteria can contaminate food through improper handling and inadequate temperature controls, allowing more toxins to be ingested.
Symptoms start fairly quickly (30 minutes to 8 hours) after eating contaminated food. Mayonnaise and cream pies are frequent culprits, although meat, eggs, and produce can be contaminated as well. The main symptom is vomiting that usually lasts less than 24 hours. Abdominal cramping and diarrhea are common symptoms as well.
Bacillus Cereus
This bacteria can grow when cooked rice is unrefrigerated too long. Other foods that can cause this illness include cheese and starchy foods like pasta, potatoes, and sushi. Symptoms of B. cereus food poisoning include vomiting and diarrhea. Symptoms often resolve within hours but may last about two days.
