What is Foodborne Illness?
Foodborne illness, also commonly called “food poisoning”, is an illness that results from eating foods or drinking liquids that are contaminated with certain types of bacteria, viruses, parasites, or toxins. While most foodborne illnesses resolve on their own and require no medical attention, some can require medications, hospitalization, or may even be life threatening and should be evaluated by a medical professional.
What are the signs and symptoms of foodborne illness?
The most common symptoms of foodborne illness are nausea, vomiting, abdominal pain, diarrhea and fevers. Some symptoms start within hours and others do not start until days to weeks after eating or drinking the offending item. More serious symptoms such as bloody bowel movements or bloody vomiting, chest pain, irregular heartbeat, headaches, confusion, changes in vision, weakness, muscle paralysis, or hallucinations can be a sign of a severe infection that should be evaluated immediately by a medical professional. Medical attention should be sought if your temperature is greater than 100.4°F (38°C) or if symptoms lead to an inability to eat, drink, or stay hydrated.
What are the potential long term effects of foodborne illness?
The majority of symptoms of foodborne illness go away in a few days. However symptoms can last for weeks to months, years or even for life. Certain types of infections can cause new long-term disease or can worsen pre-existing illnesses. Some people may experience ongoing abdominal pain, diarrhea, constipation, bloating, or cramping. Other long-term symptoms can involve skin, nerves and muscles, the heart, or joints. Any symptoms that last for more than 48 hours should be evaluated by a physician.
What are the causes of foodborne illness?
Although food allergies as well as toxic chemicals can cause symptoms similar to those described above, the focus of this paper will be on illness caused by bacteria, viruses and parasites.Bacteria
- Salmonella– Salmonella infection is the most common bacterium causing foodborne illness and leads to the highest number of hospitalizations and deaths in the United States. Foods most commonly contaminated by Salmonella include poultry, fresh produce (fruits and vegetables), eggs, meats such as beef and pork, and dairy products. This infection can cause symptoms of fever, diarrhea containing blood or mucous, and severe abdominal pain.
- Campylobacter – Campylobacter infections are common and can lead to serious short and long-term illnesses. Like Salmonella, Campylobacter can cause fever, bloody diarrhea and severe abdominal pain but can also have long-term complications that include inflammation/damage of joints or nerve damage leading to muscle weakness that can be life threatening. Like Salmonella, foods that are associated with Campylobacter infections include poultry, dairy, produce and meats such as pork and beef.
- Escherichia coli (also known as E. coli) – There are many different types of E. coli that can cause symptoms ranging from watery diarrhea and abdominal pain to bloody diarrhea that can be associated with a severe infection that involves injury to the kidneys, blood vessels / clotting, and nervous system. E. coli associated with these infections lives in the intestinal tract of cattle making beef, unprocessed milk, and contaminated produce the most common sources for E. coli infections.
- Listeria – Listeria infections are most significant in the very young, very old, pregnant women or immunosuppressed patients such as organ transplant recipients, or patients with cancer, diabetes, or HIV, and those who are on chronic immunosuppressive medications such as chemotherapy or steroids. While Listeria can cause watery bacteria in patients with a normal immune system, more severe symptoms to include infections of the brain can occur in very young, very old, or immunosuppressed patients. Pregnant women need to be particularly cautious as Listeria infection can lead to miscarriage or premature birth. Pregnant mothers may only experience mild symptoms of fever, chills, or back pain with this infection. Listeria can be transmitted through deli meats, undercooked pork and poultry, produce and seafood.
- Norovirus and Rotavirus – Both of these viruses tend to produce symptoms of nausea, vomiting, mild fevers, headache, and watery diarrhea. Rotavirus usually infects children more than adults. Norovirus is most common in adults but can affect any age group and is frequently associated with large outbreaks in restaurants/catered events, hospitals, schools, and vacation destinations including cruise ships. Infected individuals usually pass these viruses on to others by not properly washing their hands after going to the bathroom, and then preparing food or beverages.
- Hepatitis A – Hepatitis A is a virus that can cause injury to the liver and is most commonly transmitted through contamination of food or water by the feces of infected individuals. Hepatitis A infections usually appear with a mild flu-like illness with symptoms including fatigue, nausea, vomiting, fevers and abdominal pain. These infections can become more severe and include darkening of the urine, light colored bowel movements, itching, as well as yellowing of the skin and whites of the eyes.
- Cryptosporidium and Cyclospora – these two parasites can cause diarrhea, fevers, fatigue and can lead to infections of the liver, bile tract, gallbladder, and pancreas. Cryptosporidium is carried by cattle and typically infects immunosuppressed patients through contaminated water, produce, and unpasteurized milk. In contrast Cyclospora has been documented to be transmitted by fresh produce such as berries and basil as well as contaminated water sources. The infections tend to be short lived but can persist for weeks to months.
- Toxoplasma gondii – Toxoplasma is a parasite that can only reproduce in cats and causes infections when people ingest the parasite’s cysts usually through soil, food or water contaminated with cat feces. Similar to Listeria infections, it is important for pregnant females to be aware of toxoplasma as it can be transmitted from contaminated foods or litter box exposure to the mother and then to the fetus. The most common foods associated with toxoplasma contamination are beef, produce, poultry, dairy, and deli meats.
- Giardia Lamblia – This parasite may cause symptoms, including abdominal cramps, bloating and diarrhea. Individuals with immunoglobulin deficiencies (especially Immunoglobulin A) and low gastric acidity (as in elderly patients), are especially susceptible. Giardia Lamblia is usually transmitted by drinking contaminated water.
Who is at risk for acquiring foodborne illness?
Everyone is at risk for and will probably have a foodborne illness at one time in their lives. However, these illnesses typically only require medical attention when the symptoms described above become severe. There are certain populations that are at increased risk for severe illness with foodborne infections for whom medical attention should be sought if any concern exists. These include the very young, very old, pregnant women, immunosuppressed patients such as organ transplant recipients, or patients with cancer, diabetes, or HIV, and those who are on chronic immunosuppressive medications such as chemotherapy or steroids. Patients that suffer from chronic liver disease, alcoholism, or have decreased stomach acid production through surgery or chronic acid suppressing medications (such as proton pump inhibitors, for example esomeprazole, rabeprazole, or omeprazole) are also at increased risk.
How is foodborne illness diagnosed?
Foodborne illness is usually diagnosed based on your symptoms and the circumstances surrounding the start of your illness. Often the cause of the illness is not determined, particularly if symptoms are short lived. Common questions your medical provider may ask you that can help in determining the cause of your illness may include:
- What are your symptoms? Have you ever had similar symptoms before?
- Have you had any bloody bowel movements or bloody vomit, chest pain, irregular heartbeat, headaches, confusion, changes in vision, weakness, muscle paralysis, or hallucinations?
- What foods did you eat at or around the time these symptoms began?
- Did you eat any new or unusual foods? Did you eat in a new or unusual location/restaurant?
- Have you traveled recently? Have you been campling?
- Do you have pets?
- How long prior to the onset of symptoms did you eat the food in question?
- Did anyone eating with you also become ill? What symptoms did they have?
Beyond the history of illness, your provider may order blood or urine tests, imaging (X-rays or CT scan), or even an endoscopy. If you are having diarrhea a very important part of the diagnosis includes evaluating a sample of your bowel movement for the type of infection causing your symptoms. Collecting your stool is important not only for determining treatment but also allows public health officials to recognize if there is an outbreak of foodborne illness that needs to be further investigated.
How can I prevent getting a foodborne illness?
Perhaps the most important part of avoiding foodborne illness is ensuring food safety:
- Clean – Washing hands and food preparation surfaces frequently can decrease the risk of infections. Proper hand washing should include soap and warm, running water for at least 20 seconds after handling food, using the bathroom, changing diapers, or handling pets and their waste. Wash knives/utensils, cutting boards, and counter tops with warm soapy water preparing each food item before continuing with food preparation. Washing fruits and vegetables, even those with peels, with running water can prevent the spread of infections.
- Separate – Bacteria, viruses and parasites can spread illness if they cross contaminate the foods being prepared which often results from foods that are not properly separated. This is best done through using separate cutting boards and plates for fruits/vegetables and meat/poultry/seafood/eggs. These items should also be physically separated in your shopping cart and in storage/refrigerators in your home.
- Cook – Cooking all foods to a proper internal temperature can ensure the killing of bacteria, viruses and parasites. Using a food thermometer ensures proper internal food temperatures are achieved. Relying on color and texture is not sufficient to ensure food safety. Reheated/microwaved foods should be heated to at least 165°F / 74°C.
- Chill – Perishable foods should be refrigerated in 2 hours or less in a refrigerator set no higher than 40°F and a freezer at no higher than O°F. All thawing and marinating should be done in the refrigerator as bacteria can rapidly multiply on foods left at room temperature. Guidelines for storage times for refrigerated foods can be found at www.foodsafety.gov/keep/charts/storagetimes.html.
More recommended food safety information can be found online at www.foodsafety.gov.
What foods should high risk individuals avoid?
High risk individuals (very young, very old, pregnant women, immunosuppressed patients such as organ transplant recipients, or patients with cancer, diabetes, or HIV, and those who are on chronic immunosuppressive medications such as chemotherapy or steroids) should avoid the following foods:
- Raw or smoked fish/shellfish, meat, or poultry
- Raw or unpasteurized cheeses or milk or juices, soft cheeses (feta, Brie, Camembert), Mexican style cheese (queso blanco, queso fresco)
- Raw or undercooked eggs or foods containing them such as certain salad dressings, sauces, and beverages
- Hot dogs/dry or fermented sausages, pâtés , meat spreads, luncheon meats (cold cuts, deli meats)
- How are foodborne illnesses treated?
The treatment of foodborne illness is primarily supportive. Supportive treatment includes drinking adequate fluids/ensuring proper hydration, eating small, low fat meals, and resting as needed. Because these illnesses can be passed from person to person, ensuring proper hygiene (hand washing, care with diaper changing) as well as staying home from work or school are important in preventing the spread of these infections.
Antibiotics are not usually necessary, although they may be required in certain types of bacterial or parasitic infections. Anti-diarrheal medications such as loperamide are not generally recommended and should typically be avoided unless recommended by a physician.
As mentioned above, more serious symptoms such as bloody bowel movements or bloody vomit, chest pain, irregular heartbeat, headaches, confusion, changes in vision, weakness, muscle paralysis, or hallucinations can be a sign of a severe infection that should be evaluated immediately by a medical professional. Furthermore, medical attention should be sought if your temperature is greater than 100.4°F (38°C) or if symptoms lead to an inability to eat, drink, or stay hydrated.
Author(s) and Publication Date(s)
Ryan M. Kwok, MD, MAJ MC USA, and Mark S. Riddle, MD, PhD, CMDR, National Naval Medical Center, Bethesda, MD – Updated August 2013.
James A. Butler, MD, FACP, CAPT MC USN, and Greg Martin, MD, National Naval Medical Center, Bethesda, MD – Published June 2004.