Bacterial Causes of Foodborne Illness
Resources for Ensuring Food Safety in your Home
Botulinum toxin (produced by Clostridium botulinum bacteria)
Symptoms: Neurotoxic symptoms, including double vision, inability to swallow, speech difficulty, and progressive weakness of the eyes, face, mouth, and throat. Get medical help immediately. Botulism can be fatal.
Onset: Generally 4-36 hours after eating.
Source of Foodborne Illness: These bacteria produce toxins only in an anaerobic (oxygen-less) environment of little acidity. The spores are heat resistant and can survive in foods that are unsafely processed. Few outbreaks are reported annually in the U.S.; most are associated with inadequately processed, home-canned foods, but occasionally commercially-produced foods have been involved in outbreaks. Assume contamination if the food container is cracked, damaged, leaking, bulging, or swollen, oozes liquid upon opening, or if the food inside appears or smells abnormal. Sausages, meat products, canned vegetables and seafood products have been vehicles for human botulism.
Campylobacter jejuni
Symptoms: Diarrhea, abdominal cramping, fever, and sometimes bloody stools. Lasts 7-10 days.
Onset: Generally 2-5 days after eating.
Source of Foodborne Illness: Campylobacter jejuni are prevalent in the gastrointestinal system of healthy birds, cows, and other livestock. Bacteria on poultry, cattle, and sheep can contaminate meat and milk of these animals. The main food sources are: raw poultry, raw meat, and unpasteurized milk. Cross-contamination (ie. from an unwashed cutting board) is also common.
Escherichia coli O157:H7
Symptoms:Severe bloody diarrhea and abdominal cramps; sometimes the infection causes non-bloody diarrhea or no symptoms. Usually little or no fever is present, and the illness resolves in 5 to 10 days. In some persons, particularly children under 5 years of age and the elderly, the infection can also cause a complication called hemolytic uremic syndrome (HUS), in which the red blood cells are destroyed and the kidneys fail. About 2-7% of infections lead to this complication. In the United States, hemolytic uremic syndrome is the principal cause of acute kidney failure in children, and most cases of hemolytic uremic syndrome are caused by E. coli O157:H7.
Onset: Generally 2-5 days after eating.
Source of Foodborne Illness: The bacterium E. coli O157:H7 is a rare but dangerous type of E. coli. The organism can be found on a small number of cattle farms and can live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow’s udders or on equipment may get into raw milk. Main food vehicles are inadequately cooked meat (particularly ground beef), sprouts, lettuce, salami, and unpasteurized milk and juice. Contact with these foods can cross-contaminate surfaces and other foods. Individuals can also become infected by swimming in or drinking sewage-contaminated water or bacteria present in stools of infected persons, which can be transferred through deficient hygiene and handwashing practices. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected. Young children typically shed the organism in their feces for a week or two after their illness resolves.
Listeria monocytogenes
Symptoms:Fever, headache, nausea, vomiting, and muscle aches. In pregnant women, can cause fetal and infant death. Primarily affects pregnant women and their fetuses, newborns, the elderly, people with cancer, and those with impaired immune systems.
Onset: From 7-30 days after eating, but most symptoms have been reported 48-72 hours after consumption of contaminated food.
Source of Foodborne Illness: Main food vehicles include soft cheese, unpasteurized milk, ready-to-eat processed meat (hot dogs and deli meats), cooked seafood and shellfish products, fresh fruits and vegetables, and prepared, stored, deli salads.. Compared to other microorganisms, L. monocytogenes is relatively resistant to heat, salt, and acidity. It can also grow at refrigeration temperatures.
Clostridium perfringens
Symptoms: Abdominal pain, diarrhea, and occasionally nausea and vomiting. Symptoms up to a day and are usually mild. Can be more serious in older or debilitated people.
Onset: Generally 8-12 hours after eating.
Source of Foodborne Illness: C. perfringens is unique as it can survive cooking and multiplies rapidly when food is held at temperatures between 120 and 130˚F, as during cool down and storage of prepared foods. Meats and meat products are the foods most frequently implicated. Foods like gravies and stuffing must be kept above 140° F to prevent contamination.
Salmonella bacteria
Symptoms: Diarrhea, fever, abdominal cramps, vomiting.
Onset: Generally 8-12 hours after eating.
Source of Foodborne Illness: Salmonella are present in human and animal digestive systems and can contaminate food or water. Raw meats, poultry, eggs, milk and other dairy products, shrimp, frog legs, yeast, coconut, pasta and chocolate are most frequently involved. Children under 5 are the most frequently infected and adults over 65 manifest the disease most severely.
Shigella bacteria
Symptoms: Abdominal cramps, diarrhea, fever, sometimes vomiting, and blood, pus, or mucus in stool.
Onset: 1-7 days after eating.
Source of Foodborne Illness: Shigella bacteria are found in the stool of humans infected with diarrheal illness. Food becomes contaminated when a human carrier does not wash hands and then handles liquid or food that is not thoroughly cooked afterwards. Organisms multiply when contaminated food is left at room temperature. Commonly implicated food vehicles are milk and dairy products, poultry, and potato salad.
Staphylococcal enterotoxin (produced by Staphylococcus aureus bacteria)
Symptoms: Diarrhea, vomiting, nausea, abdominal pain, cramps, and prostration. Lasts 24-48 hours. Rarely fatal.
Onset: Generally 30 minutes to 8 hours after eating.
Source of Foodborne Illness: Approximately one-fourth of people and animals naturally carry Staph; they can contaminate food through improper handwashing. When contaminated food is left too long at room temperature, toxins are produced. Meats, poultry, egg products, tuna, potato and macaroni salads, and cream-filled pastries are good environments for these bacteria to produce toxins.
Vibrio vulnificus
Symptoms:Chills, fever, and/or prostration. Those with liver conditions, low gastric (stomach) acid, and weakened immune systems are at high risk.
Onset: Within 24 hours of ingestion.
Source of Foodborne Illness: The bacteria live in coastal waters and can infect humans either through open wounds or through consumption of contaminated seafood, particularly raw or undercooked shellfish and oysters. The bacteria are most numerous in warm weather.
Protozoa Causes of Foodborne Illness
Entamoeba histolytica
Symptoms: Merely 10-20% of those infected experience symptoms, which can include severe stomach cramping, tenderness over the colon or liver, loose morning stools, recurrent diarrhea, weight loss, fatigue, and sometimes anemia.
Onset: 2-4 weeks after exposure.
Source of Foodborne Illness: E. histolytica exist in the intestinal tract of humans and are expelled in feces. Water and vegetables grown in contaminated soil spread the infection. Amebiases is most common in individuals who live or travel in tropical areas with inadequate sanitation.
Giardia lamblia
Symptoms: Sudden onset of explosive watery stools, abdominal cramps, gas, anorexia, nausea, and vomiting. Especially infects hikers, children, travelers, and institutionalized patients.
Onset: 1-3 weeks.
Source of Foodborne Illness: G. lamblia is a parasite passed in the stools of those infected. Giardiasis occurs when one consumes these bacteria, most frequently from contaminated water or surfaces. It may also be transmitted by uncooked foods that become contaminated while growing or after cooking by infected food handlers. Cool, moist conditions favor the organism’s survival.
Viral Causes of Foodborne Illness
Symptoms: Nausea, vomiting, diarrhea, abdominal pain. Headache and low-grade fever may also accompany this infection. Lasts for 24 to 60 hours.
Onset: Generally 12-48 hours after exposure.
Source of Foodborne Illness: Norovirus is an extremely common cause of foodborne illness, and the leading cause of acute gastroenteritis. However, it is rarely diagnosed because the laboratory test is not widely available. Norwalk-like virus spreads primarily from one infected person to another. Infected persons can contaminate foods such as salads and sandwiches as they prepare it if they have the virus on their hands.
Symptoms: Begins with malaise, appetite loss, nausea, vomiting, and fever. After 3-10 days patient develops jaundice with darkened urine. Severe cases can cause liver damage and death.
Onset: 1-10 days, can last up to 2 months.
Source of Foodborne Illness: Hepatitis A can be spread person-to-person, or contaminate food during growing, harvesting, processing, handling, or after cooking. Mollusks (oysters, clams, mussels, scallops, and cockles) become carriers when their beds are polluted by untreated sewage. Raw shellfish are especially potent carriers, although cooking does not always kill the virus. Fortunately, there is a vaccine for this disease.