- What is food poisoning
- Food poisoning signs and symptoms
- What Causes Food Poisoning
- Clostridium perfringens
- Staphylococcus aureus (Staph)
- Listeria (Listeriosis)
- Risk factors for food poisoning
- Complications of food poisoning
- Prevention of food poisoning
- Food poisoning diagnosis
- How to treat food poisoning
What is food poisoning
Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.
- The Centers for Disease Control and Prevention 1) estimates that each year 48 million people get sick from a foodborne illness, 128,000 are hospitalized, and 3,000 die. CDC estimates that 1 in 6 Americans get sick from eating contaminated food every year.
If you have food poisoning you’ll probably have gastroenteritis symptoms such as nausea, abdominal cramps, diarrhea or vomiting or flu-like symptoms, which can start within hours of eating contaminated food. Most people have only mild illnesses, lasting a few hours to several days. However, some develop severe illness requiring hospitalization, and some illnesses result in long-term health problems and occasionally people die from food poisoning. Infections transmitted by food can result in chronic arthritis, brain and nerve damage and hemolytic uremic syndrome, which causes kidney failure. But most often, food poisoning is mild and resolves without treatment.
Some wild mushrooms, including the death cap, are extremely poisonous. You should not eat wild-harvested mushrooms unless they have been definitely identified as safe. Seek immediate medical treatment If you think you may have eaten poisonous mushrooms.
Large fish, such as shark, swordfish and marlin, may accumulate relatively high levels of mercury. You should limit your consumption of these fish, especially if you are a child, are pregnant or planning pregnancy.
Drink plenty of liquids to replace fluids that are lost from throwing up and diarrhea.
If diarrhea is severe, oral rehydration solution such as Ceralyte, Pedialyte or Oralyte, should be drunk to replace the fluid losses and prevent dehydration. Sports drinks such as Gatorade do not replace the losses correctly and should not be used for the treatment of diarrheal illness. Sports drinks may not replace important nutrients and minerals. Oral rehydration fluids that you can get over the counter are most helpful for mild dehydration.
If you think you or someone you are caring for is severely dehydrated, see a doctor.
Food poisoning signs and symptoms
Food poisoning symptoms may range from mild to severe and may differ depending on the germ and toxin you swallowed. Most types of food poisoning cause one or more of the following signs and symptoms:
- Watery or bloody diarrhea
- Abdominal pain and cramps
Signs and symptoms may start within hours after eating the contaminated food, or they may begin days or even weeks later. Sickness caused by food poisoning generally lasts from a few hours to several days.
What Causes Food Poisoning
Contamination of food can happen at any point of production: growing, harvesting, processing, storing, shipping or preparing. Cross-contamination — the transfer of harmful organisms from one surface to another — is often the cause. This is especially troublesome for raw, ready-to-eat foods, such as salads or other produce. Because these foods aren’t cooked, harmful organisms aren’t destroyed before eating and can cause food poisoning.
Many bacterial, viral or parasitic agents cause food poisoning. The following table shows some of the possible contaminants, when you might start to feel symptoms and common ways the organism is spread.
The top five germs that cause illnesses from food eaten in the United States are:
- Clostridium perfringens
- Staphylococcus aureus (Staph)
Some other germs don’t cause as many illnesses, but when they do, the illnesses are more likely to lead to hospitalization. Those germs include:
|Contaminant||Onset of symptoms||Foods affected and means of transmission|
|Campylobacter||2 to 5 days||Meat and poultry. Contamination occurs during processing if animal feces contact meat surfaces. Other sources include unpasteurized milk and contaminated water.|
|Clostridium botulinum||12 to 72 hours||Home-canned foods with low acidity, improperly canned commercial foods, smoked or salted fish, potatoes baked in aluminum foil, and other foods kept at warm temperatures for too long.|
|Clostridium perfringens||8 to 16 hours||Meats, stews and gravies. Commonly spread when serving dishes don’t keep food hot enough or food is chilled too slowly.|
|Escherichia coli (E. coli) O157:H7||1 to 8 days||Beef contaminated with feces during slaughter. Spread mainly by undercooked ground beef. Other sources include unpasteurized milk and apple cider, alfalfa sprouts, and contaminated water.|
|Giardia lamblia||1 to 2 weeks||Raw, ready-to-eat produce and contaminated water. Can be spread by an infected food handler.|
|Hepatitis A||28 days||Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.|
|Listeria||9 to 48 hours||Hot dogs, luncheon meats, unpasteurized milk and cheeses, and unwashed raw produce. Can be spread through contaminated soil and water.|
|Noroviruses (Norwalk-like viruses)||12 to 48 hours||Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.|
|Rotavirus||1 to 3 days||Raw, ready-to-eat produce. Can be spread by an infected food handler.|
|Salmonella||1 to 3 days||Raw or contaminated meat, poultry, milk, or egg yolks. Survives inadequate cooking. Can be spread by knives, cutting surfaces or an infected food handler.|
|Shigella||24 to 48 hours||Seafood and raw, ready-to-eat produce. Can be spread by an infected food handler.|
|Staphylococcus aureus||1 to 6 hours||Meats and prepared salads, cream sauces, and cream-filled pastries. Can be spread by hand contact, coughing and sneezing.|
|Vibrio vulnificus||1 to 7 days||Raw oysters and raw or undercooked mussels, clams, and whole scallops. Can be spread through contaminated seawater.|
Norovirus is a very contagious virus that can infect anyone. You can get it from an infected person, contaminated food or water, or by touching contaminated surfaces 3). The virus causes your stomach or intestines or both to get inflamed. This leads you to have stomach pain, nausea, and diarrhea and to throw up. These symptoms can be serious for some people, especially young children and older adults.
Noroviruses were previously called Norwalk-like viruses. They are a group of non-enveloped, single-stranded RNA viruses that cause acute gastroenteritis. Noroviruses belong to the family Caliciviridae that includes sapoviruses, which also causes acute gastroenteritis.
Currently, there are six recognized norovirus genogroups. Three of the genogroups (GI, GII, and GIV) affect humans. More than 25 different genotypes have been identified within these three genogroups. Since 2002, variants of the GII.4 genotype have been the most common cause of norovirus outbreaks. Since there are many different types of noroviruses, people can get infected many times during their lifetime. It is possible to develop immunity to specific types. But, it is not known how long immunity lasts. This may explain why so many people of all ages get infected during norovirus outbreaks. Also, whether someone is susceptible to norovirus infection or not may be determined in part by his or her genes.
Norovirus is the leading cause of illness and outbreaks from contaminated food in the United States. Most of these outbreaks occur in the food service settings like restaurants. Infected food workers are frequently the source of the outbreaks, often by touching ready-to-eat foods, such as raw fruits and vegetables, with their bare hands before serving them. However, any food served raw or handled after being cooked can get contaminated with norovirus.
Norovirus outbreaks can also occur from foods, such as oysters, fruits, and vegetables, that are contaminated at their source.
Noroviruses can be found in your vomit or stool even before you start feeling sick. The virus can stay in your stool for 2 weeks or more after you feel better. So, it is important to continue washing your hands often during this time.
Norovirus is a highly contagious virus. Anyone can get infected with norovirus and get sick. Also, you can get norovirus illness many times in your life. One reason for this is that there are many different types of noroviruses. Being infected with one type of norovirus may not protect you against other types.
Norovirus can be found in your stool (feces) even before you start feeling sick. The virus can stay in your stool for 2 weeks or more after you feel better.
You are most contagious:
- when you are sick with norovirus illness, and
- during the first few days after you recover from norovirus illness.
You can become infected with norovirus by accidentally getting stool or vomit from infected people in your mouth. This usually happens by:
- eating food or drinking liquids that are contaminated with norovirus,
- touching surfaces or objects contaminated with norovirus then putting your fingers in your mouth, or
- having contact with someone who is infected with norovirus (for example, caring for or sharing food or eating utensils with someone with norovirus illness).
Norovirus can spread quickly in closed places like daycare centers, nursing homes, schools, and cruise ships. Most norovirus outbreaks happen from November to April in the United States.
Norovirus Infection Symptoms
Norovirus causes inflammation of the stomach or intestines or both. This is called acute gastroenteritis.
The most common symptoms:
- throwing up
- stomach pain
- body aches
A person usually develops symptoms 12 to 48 hours after being exposed to norovirus. Most people with norovirus illness get better within 1 to 3 days.
If you have norovirus illness, you can feel extremely ill and throw up or have diarrhea many times a day. This can lead to dehydration, especially in young children, older adults, and people with other illnesses.
Symptoms of dehydration:
- decrease in urination
- dry mouth and throat
- feeling dizzy when standing up
Children who are dehydrated may cry with few or no tears and be unusually sleepy or fussy.
Norovirus Infection Treatment
There is no specific medicine to treat people with norovirus illness. Norovirus infection cannot be treated with antibiotics because it is a viral (not a bacterial) infection.
If you have norovirus illness, you should drink plenty of liquids to replace fluid lost from throwing up and diarrhea. This will help prevent dehydration.
Sports drinks and other drinks without caffeine or alcohol can help with mild dehydration. But, these drinks may not replace important nutrients and minerals. Oral rehydration fluids that you can get over the counter are most helpful for mild dehydration.
Dehydration can lead to serious problems. Severe dehydration may require hospitalization for treatment with fluids given through your vein (intravenous or IV fluids). If you think you or someone you are caring for is severely dehydrated, see the doctor.
Preventing Norovirus Infection
Practice proper hand hygiene
Wash your hands carefully with soap and water:
- especially after using the toilet and changing diapers, and
- always before eating, preparing, or handling food.
- Alcohol-based hand sanitizers can be used in addition to hand washing. But, they should not be used as a substitute for washing with soap and water.
Wash fruits and vegetables and cook seafood thoroughly
Carefully wash fruits and vegetables before preparing and eating them. Cook oysters and other shellfish thoroughly before eating them.
Be aware that noroviruses are relatively resistant. They can survive temperatures as high as 140°F and quick steaming processes that are often used for cooking shellfish.
Food that might be contaminated with norovirus should be thrown out.
Keep sick infants and children out of areas where food is being handled and prepared.
When you are sick, do not prepare food or care for others who are sick
You should not prepare food for others or provide healthcare while you are sick and for at least 2 days after symptoms stop. This also applies to sick workers in settings such as schools and daycares where they may expose people to norovirus.
Many local and state health departments require that food workers and preparers with norovirus illness not work until at least 48 hours after symptoms stop. If you were recently sick, you can be given different duties in the restaurant, such as working at a cash register or hosting.
Clean and disinfect contaminated surfaces
After throwing up or having diarrhea, immediately clean and disinfect contaminated surfaces. Use a chlorine bleach solution with a concentration of 1000–5000 ppm (5–25 tablespoons of household bleach [5.25%] per gallon of water) or other disinfectant registered as effective against norovirus by the Environmental Protection Agency 4).
Wash laundry thoroughly
Immediately remove and wash clothes or linens that may be contaminated with vomit or stool (feces).
- handle soiled items carefully without agitating them,
- wear rubber or disposable gloves while handling soiled items and wash your hands after, and
- wash the items with detergent at the maximum available cycle length then machine dry them.
Salmonella is a bacteria that makes people sick. It was discovered by an American scientist named Dr. Salmon, and has been known to cause illness for over 125 years. The illness people get from a Salmonella infection is called salmonellosis. There are many different kinds of Salmonella bacteria. Salmonella serotype Typhimurium 5) and Salmonella serotype Enteritidis 6) are the most common in the United States 7). Salmonella infections are more common in the summer than winter.
Every year, Salmonella is estimated to cause 1.2 million foodborne illnesses in the United States, with 19,000 hospitalizations and 450 deaths 8). Most people infected with Salmonella develop diarrhea, fever, and abdominal cramps between 12 and 72 hours after infection. The illness usually lasts 4 to 7 days, and most individuals recover without treatment. In some cases, diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites. In these cases, Salmonella can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness 9).
Children are at the highest risk for Salmonella infection. Children under the age of 5 10) have higher rates of Salmonella infection than any other age group 11). Young children, older adults, and people with weakened immune systems are the most likely to have severe infections 12).
How people get Salmonella
Salmonella live in the intestinal tracts of humans and animals. You can get Salmonella infection from a variety of sources, including:
- Eating contaminated food or drinking contaminated water.
- Touching infected animals and not washing your hands afterwards.
Contaminated Food or Water
Salmonella is usually transmitted to humans by eating foods contaminated with small amounts of animal feces. Contaminated foods usually look and smell normal. They are often foods of animal origin, such as beef, poultry, milk, fish, or eggs, but any food, including vegetables and fruit or processed foods, may become contaminated.
Foods can also be contaminated in the kitchen. Drippings from raw meat or poultry can contaminate surfaces and other foods in the refrigerator or shopping cart. When raw meat or poultry are prepared with a cutting board and knife without being washed thoroughly between uses, they can contaminate other foods.
When preparing raw meat or poultry, food handlers can transfer Salmonella on their hands to other foods if they do not wash their hands between food preparation steps. Food handlers who do not wash their hands with soap after using the bathroom can also contaminate food with Salmonella.
Contact with Infected Animals
Salmonella live in the intestinal tracts of humans and other animals, including poultry and other birds, amphibians, and reptiles. Salmonella may be found in the feces of some animals, and people can become infected if they do not wash their hands after contact with animals or animal feces.
Many animals can carry Salmonella germs but appear perfectly healthy and clean. Animals’ bodies, whether covered with fur, feathers, or scales, can be contaminated with germs. Reptiles, such as turtles, lizards, and snakes, are particularly likely to harbor Salmonella. Many chicks, ducks, and other poultry including those in backyard flocks can carry Salmonella in their feces. You cannot look at an animal and tell if it is infected with Salmonella.
The area where an animal lives, such as its cage or water in its tank or the places where an animal roams, may be contaminated with Salmonella, which can cause illness in people who come into direct contact with the animal area, cage, or tank water.
Long-Term Consequences to a Salmonella Infection?
People with diarrhea due to a Salmonella infection usually recover completely, although it may be several months before their bowel habits are entirely normal.
A small number of people with Salmonella develop pain in their joints. This is called reactive arthritis. Reactive arthritis can last for months or years and can lead to chronic arthritis, which can be difficult to treat 13). Antibiotic treatment of the initial Salmonella infection does not make a difference in whether or not the person develops arthritis 14). People with reactive arthritis can also develop irritation of the eyes and painful urination 15).
How Can Salmonella Infections Be Diagnosed?
Diagnosing salmonellosis requires testing a clinical specimen (such as stool or blood) from an infected person to distinguish it from other illnesses that can cause diarrhea, fever, and abdominal cramps. Once Salmonella is identified in the specimen, additional testing can be done to further characterize the Salmonella.
Salmonella Infection Prevention
There is no vaccine to prevent salmonellosis. Because foods of animal origin may be contaminated with Salmonella, people should not eat raw or undercooked eggs, poultry, or meat. Raw eggs may be unrecognized in some foods, such as homemade Hollandaise sauce, Caesar and other homemade salad dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie dough, and frostings. Poultry and meat, including hamburgers, should be well-cooked, not pink in the middle. Persons also should not consume raw or unpasteurized milk or other dairy products. Produce should be thoroughly washed.
Cross-contamination of foods should be avoided. Uncooked meats should be kept separate from produce, cooked foods, and ready-to-eat foods. Hands, cutting boards, counters, knives, and other utensils should be washed thoroughly after touching uncooked foods. Hand should be washed before handling food, and between handling different food items.
Tips for Preventing Salmonella
- Cook poultry, ground beef, and eggs thoroughly. Do not eat or drink foods containing raw eggs, or raw (unpasteurized) milk.
- If you are served undercooked meat, poultry or eggs in a restaurant, don’t hesitate to send it back to the kitchen for further cooking.
- Wash hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry.
- Be particularly careful with foods prepared for infants, the elderly, and the immunocompromised.
- Wash hands with soap after handling reptiles, birds, or baby chicks, and after contact with pet feces.Avoid direct or even indirect contact between reptiles (turtles, iguanas, other lizards, snakes) and infants or immunocompromised persons.
- Don’t work with raw poultry or meat, and an infant (e.g., feed, change diaper) at the same time.
- Mother’s milk is the safest food for young infants. Breastfeeding prevents salmonellosis and many other health problems.
- People who have salmonellosis should not prepare food or pour water for others until their diarrhea has resolved. Many health departments require that restaurant workers with Salmonella infection have a stool test showing that they are no longer carrying the Salmonella bacterium before they return to work.
People should wash their hands after contact with animal feces. Because reptiles are particularly likely to have Salmonella, and it can contaminate their skin, everyone should immediately wash their hands after handling reptiles. Reptiles (including turtles) are not appropriate pets for small children and should not be in the same house as an infant. Salmonella carried in the intestines of chicks and ducklings contaminates their environment and the entire surface of the animal. Children can be exposed to the bacteria by simply holding, cuddling, or kissing the birds. Children should not handle baby chicks or other young birds. Everyone should immediately wash their hands after touching birds, including baby chicks and ducklings, or their environment.
How Can Salmonella Infections Be Treated?
Salmonella gastrointestinal infections usually resolve, or get better, in 5-7 days. Most do not require treatment other than oral fluids. People with severe diarrhea may require rehydration with intravenous fluids.
Antibiotics are recommended only for patients who:
- Have a serious illness (such as severe diarrhea, high fever, bloodstream infection, or condition requiring hospitalization).
- Are considered at high risk for serious disease or complications (such as infants, adults over 65 years old, and people with weakened immune systems).
Some Salmonella bacteria are resistant to antibiotics. Sometimes the bacteria that cause infections are resistant to the drug of choice, and this drug doesn’t work. Physicians must then recommend second- or third-choice drugs for treatment, but these drugs might be less effective, more toxic, or more expensive. Choices for antibiotic therapy for severe infections often include fluoroquinolones, third-generation cephalosporins, or ampicillin.
Resistance to antimicrobial agents is not uncommon in Salmonella. Data from the National Antimicrobial Resistance Monitoring System show that 5% of non-typhoidal Salmonella are resistant to five or more antimicrobial agents 16).
Clostridium perfringens (C. perfringens) is a spore-forming gram-positive bacterium that is found in many environmental sources as well as in the intestines of humans and animals. C. perfringens is commonly found on raw meat and poultry. It prefers to grow in conditions with very little or no oxygen, and under ideal conditions can multiply very rapidly. Some strains of C. perfringens produce a toxin in the intestine that causes illness.
C. perfringens can survive high temperatures. During cooling and holding of food at temperatures from 54°F–140°F (12°C–60°C), the bacteria grows. It can grow very rapidly between 109°F–117°F (43°C–47°C). If the food is served without reheating to kill the bacteria, live bacteria may be eaten. The bacteria produce a toxin inside the intestine that causes illness.
Centers for Disease Control and Prevention estimates Clostridium perfringens (C. perfringens) causes nearly 1 million cases of foodborne illness each year 17).
Everyone is susceptible to food poisoning from C. perfringens. The very young and elderly are most at risk of C. perfringens infection and can experience more severe symptoms that may last for 1 to 2 weeks. Complications, including dehydration, may occur in severe cases.
Common food sources of C. perfringens
Beef, poultry, gravies, and dried or pre-cooked foods are common sources of C. perfringens infections. C. perfringens infection often occurs when foods are prepared in large quantities and kept warm for a long time before serving. Outbreaks often happen in institutions, such as hospitals, school cafeterias, prisons, and nursing homes, or at events with catered food.
Prevention of C. perfringens food poisoning
- Cook and keep food at the correct temperature
- Food, especially roasts of beef or poultry, should be cooked to a safe internal temperature, and then kept at 140°F (60°C) or warmer or 40°F (4.4°C) or cooler. These temperatures prevent the growth of C. perfringens spores that might have survived cooking. Meat dishes should be served hot, within 2 hours after cooking.
- Refrigerate leftovers and reheat them properly. Leftover foods should be refrigerated at 40°F or colder as soon as possible and within 2 hours of preparation. It is OK to put hot foods directly into the refrigerator. However, large amounts of food, such as soups, stews, and big cuts of meats, such as roasts, should be divided into small quantities for refrigeration. Leftovers should be reheated to at least 165°F (74°C) before serving.
- When in doubt, throw it out. Foods that have dangerous bacteria in them may not taste, smell, or look different. Any food that has been left out too long may be dangerous to eat, even if it looks OK.
Symptoms of C. perfringens food poisoning
People infected with C. perfringens develop diarrhea and abdominal cramps within 6 to 24 hours (typically 8 to 12 hours). The illness usually begins suddenly and lasts for less than 24 hours. People infected with C. perfringens usually do not have fever or vomiting. The illness is not passed from one person to another.
How is C. perfringens diagnosed and treated?
Laboratories diagnose C. perfringens food poisoning by detecting a type of bacterial toxin in feces or by tests to determine the number of bacteria in the feces. A count of at least 106 C. perfringens spores per gram of stool within 48 hours of when illness began is required to diagnose infection. Oral rehydration or in severe cases, intravenous fluids and electrolyte replacement can be used to prevent or treat dehydration. Antibiotics are not recommended.
Campylobacter are bacteria that can make people and animals sick. Most human illness is caused by one species, called Campylobacter jejuni, but other species also can cause human illness 18). Campylobacter infection, or campylobacteriosis, is an infectious disease caused by Campylobacter bacteria. It is one of the most common causes of diarrheal illness in the United States. The Foodborne Diseases Active Surveillance Network 19) indicates that about 14 cases are diagnosed each year for every 100,000 people. Many more cases go undiagnosed or unreported. The Centers for Disease Control and Prevention estimates Campylobacter infection affects more than 1.3 million people every year. Most cases are not part of recognized outbreaks, and more cases occur in summer than in winter.
Most illnesses likely occur due to eating raw or undercooked poultry, or to eating something that touched it. Some are due to contaminated water, contact with animals, or drinking raw (unpasteurized) milk.
Most people with a Campylobacter infection recover completely within a week, although they may shed (get rid of) Campylobacter bacteria in their stool for several weeks after recovery, which might result in person-to-person transmission. Campylobacter infection rarely results in long-term consequences. Some studies have estimated that 5–20% of people with Campylobacter infection develop irritable bowel syndrome for a limited time and 1–5% develop arthritis.
About 1 in every 1,000 reported Campylobacter illnesses leads to Guillain-Barré syndrome. Guillain-Barré syndrome happens when a person’s immune system is triggered by an earlier infection, such as Campylobacter infection. Guillain-Barré syndrome can lead to muscle weakness and sometimes paralysis that can last for a few weeks to several years, and often requires intensive medical care. Most people recover fully, but some have permanent nerve damage, and some have died of Guillain-Barré syndrome. As many as 40% of Guillain-Barré syndrome cases in the United States may be triggered by Campylobacter infection.
Symptoms of Campylobacter infection
People with Campylobacter infection usually have diarrhea (often bloody), fever, and abdominal cramps. The diarrhea may be accompanied by nausea and vomiting. These symptoms usually start within two to five days after exposure and last about a week. Some infected people do not have any symptoms. In people with weakened immune systems, such as people with the blood disorders thalassemia and hypogammaglobulinemia, AIDS, or people receiving some kinds of chemotherapy, Campylobacter occasionally spreads to the bloodstream and causes a life-threatening infection.
How does food and water get contaminated with Campylobacter?
Many chickens, cows, and other birds and animals that show no signs of illness carry Campylobacter. Campylobacter can be carried in the intestines, liver, and giblets of animals and can be transferred to other edible parts of an animal when it’s slaughtered. In 2014, National Antimicrobial Resistance Monitoring System 20) testing found Campylobacter on 33% of raw chicken bought from retailers.
Milk can become contaminated when a cow has a Campylobacter infection in her udder or when milk is contaminated with manure. Other foods, such as fruits and vegetables, can be can become contaminated through contact with soil containing feces from cows, birds, or other animals. Animal feces can also contaminate lakes and streams. Pasteurization of milk, washing or scrubbing of fruits and vegetables, and disinfection of drinking water helps prevent illness.
How do people get infected with Campylobacter bacteria?
Most Campylobacter infections are associated with eating raw or undercooked poultry or from contamination of other foods by these items. People can get infected when a cutting board that has been used to cut and prepare raw chicken isn’t washed before it is used to prepare foods that are served raw or lightly cooked, such as salad or fruit. People also can get infected through contact with the feces of a dog or cat. Campylobacter does not usually spread from one person to another.
Outbreaks of Campylobacter infections have been associated most often with poultry, raw (unpasteurized) dairy products, untreated water, and produce.
Campylobacter infection is common in the developing world, and people who travel abroad have a greater chance of becoming infected. About 1 in 5 Campylobacter infections reported to the Foodborne Diseases Active Surveillance Network 21) are associated with international travel.
Even more rarely, people may become infected through contaminated blood during a transfusion.
How is Campylobacter infection diagnosed and treated?
Campylobacter infection is diagnosed when a laboratory test detects Campylobacter bacteria in stool, body tissue, or fluids. The test could be a culture that isolates the bacteria or a rapid diagnostic test that detects genetic material of the bacteria.
Most people with Campylobacter infection recover without specific treatment. Patients should drink extra fluids as long as the diarrhea lasts. Antibiotics are needed only for patients who are very ill or at high risk for severe disease, such as people with severely weakened immune systems, such as people with the blood disorders thalassemia and hypogammaglobulinemia, AIDS, or people receiving chemotherapy.
Staphylococcus aureus (Staph)
Staphylococcal food poisoning is a gastrointestinal illness caused by eating foods contaminated with toxins produced by the bacterium Staphylococcus aureus (Staph). Staph is found on the skin and in the nose of about 25% of healthy people and animals. It usually does not cause illness in healthy people, but Staph has the ability to make toxins that can cause food poisoning.
Patients with this illness are not contagious because the toxins are not transmitted from one person to another.
Toxin-producing Staph can be identified in stool or vomit using specialized techniques. The toxins can also be detected in foods. Suspicion of staphylococcal food poisoning is generally based only on the signs and symptoms of the patient. Testing for the toxin-producing bacteria or the toxin is not usually done in individual patients, but can be done for outbreaks. If you think you may have food poisoning, see your doctor.
How do people get staphylococcal food poisoning?
People who carry Staph can contaminate food if they don’t wash their hands before touching it. Staph can also be found in unpasteurized milk and cheese products. Because Staph is salt tolerant, it can grow in salty foods like ham. As it multiplies in food, Staph produces toxins. Although Staph bacteria are easily killed by cooking, the toxins are resistant to heat and so cannot be destroyed by cooking.
Foods at highest risk of transmitting Staph toxins are those that people handle and then do not cook. Examples are sliced meat, puddings, pastries, and sandwiches. Food contaminated with Staph toxin may not smell bad or look spoiled.
Staphylococcal food poisoning prevention
Staphylococcal food poisoning can be prevented by preventing the contamination of food with Staph. The following food safety tips can help protect you and your family:
- Wash hands and under fingernails thoroughly with soap and water before handling and preparing food.
- Do not prepare food if you are ill.
- If you have wounds or infections on your hands or wrists, wear gloves while preparing food.
- Keep kitchens and food serving areas clean.
- If food is to be stored longer than two hours, keep hot foods hot (warmer than 140°F) and cold foods cold (40°F or colder).
- Store cooked food in a wide, shallow container and refrigerate as soon as possible.
What are the symptoms of staphylococcal food poisoning?
Staphylococcal toxins are fast-acting, symptoms usually develop within 30 minutes to 6 hours. Patients typically experience vomiting, nausea, stomach cramps, and diarrhea. The illness cannot be passed to other people and typically lasts for only 1 day. Severe illness is rare.
How is staphylococcal food poisoning treated?
For most patients, staphylococcal food poisoning is a brief illness. The most important treatment is plenty of fluids. Medicines may be given to decrease vomiting and nausea. Patients with severe illness may require intravenous fluids in a hospital.
Antibiotics are not useful in treating this illness because the toxin is not affected by antibiotics.
Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes. An estimated 1,600 people get listeriosis each year, and about 260 die. The disease primarily affects pregnant women, newborns, older adults, and people with weakened immune systems. It’s rare for people in other groups to get sick with Listeria infection.
- Listeriosis is usually caused by eating food contaminated with Listeria monocytogenes. If infection occurs during pregnancy, Listeria bacteria can spread to the baby through the placenta.
- Outbreaks of Listeria infections in the 1990s were primarily linked to deli meats and hot dogs. Now, Listeria outbreaks are often linked to dairy products and produce. Investigators have traced recent outbreaks to soft cheeses, celery, sprouts, cantaloupe, and ice cream.
Listeriosis is usually a mild illness for pregnant women, but it causes severe disease in the fetus or newborn baby 22). Some people with Listeria infections, most commonly adults 65 years and older and people with weakened immune systems, develop severe infections of the bloodstream (causing sepsis) or brain (causing meningitis or encephalitis). Listeria infections can sometimes affect other parts of the body, including bones, joints, and sites in the chest and abdomen.
Food sources of Listeria
Queso fresco and other soft cheeses
Soft cheeses made with unpasteurized milk (also called raw milk) are estimated to be 50 to 160 times more likely to cause Listeria infection than when they are made with pasteurized milk.
Although pasteurization of milk kills Listeria, products made from pasteurized milk can still become contaminated if they are produced in facilities with unsanitary conditions.
Recommendations for everyone:
- Make sure the label says, “Made with pasteurized milk.”
- Be aware that Hispanic-style cheeses made from pasteurized milk, such as queso fresco, have caused Listeria infections, most likely because they were contaminated during cheese-making.
Recommendations for people at higher risk, including pregnant women, older adults, and people with weakened immunity:
- Avoid eating soft cheese, such as queso fresco, queso blanco, panela (queso panela), brie, Camembert, blue-veined, or feta, unless it is labeled as made with pasteurized milk.
Sprouts need warm and humid conditions to sprout and grow. These conditions are also ideal for the growth of bacteria, including Listeria, Salmonella, and E. coli.
Recommendations for people at higher risk, including pregnant women, older adults, and people with weakened immunity:
- Do not eat raw or lightly cooked sprouts of any kind (including alfalfa, clover, radish, and mung bean sprouts).
- Cook sprouts thoroughly to reduce your risk for getting sick. Thorough cooking kills the harmful bacteria.
- When you’re eating out, ask that raw sprouts not be added to your food. If you buy a ready-made sandwich, salad, or Asian food, check to make sure it doesn’t contain raw sprouts.
NOTE: Rinsing sprouts will not remove bacteria. Home-grown sprouts also can make you sick if you eat them raw or lightly cooked.
Recommendations for everyone:
- Eat cut melon right away or refrigerate it.
- Keep cut melon refrigerated at 41° F or colder and for no more than 7 days.
- Throw away cut melons left at room temperature for more than 4 hours.
Hot dogs, pâtés, lunch meats, and cold cuts
Recommendations for everyone:
- Don’t let juice from hot dog and lunch meat packages get on other foods, utensils, and food preparation surfaces. Wash hands after handling hot dogs, lunch meats, and deli meats.
- Safely store products in the refrigerator:
- Hot dogs: Store opened packages no longer than 1 week in the refrigerator and unopened packages no longer than 2 weeks in the refrigerator.
- Lunch and deli meat: Store factory-sealed, unopened packages no longer than 2 weeks in the refrigerator. Store opened packages and meat sliced at a local deli no longer than 3 to 5 days in the refrigerator.
Recommendations for people at higher risk, including pregnant women, older adults, and people with weakened immunity:
- Avoid eating hot dogs, lunch meats, cold cuts, other deli meats (such as bologna), or fermented or dry sausages unless they are heated to an internal temperature of 165°F or until steaming hot just before serving.
- Do not eat refrigerated pâté or meat spreads from a deli or meat counter or from the refrigerated section of a store. Foods that do not need refrigeration, like canned or shelf-stable pâté and meat spreads, are safe to eat. Refrigerate these foods after opening.
A food is called shelf-stable if it can be safely stored at room temperature or “on the shelf.”
Eating canned and shelf-stable tuna, salmon, and other fish products is not considered to increase your chance of getting sick from Listeria.
It’s important to know that not all canned foods are shelf-stable. Some canned foods are labeled “Keep Refrigerated.” Examples of such items include refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna, and mackerel. Refrigerated smoked seafood items are often labeled as “nova-style,” “lox,” “kippered,” “smoked,” or “jerky” and typically found at seafood or deli counters of grocery stores and delicatessens.
- Do not eat refrigerated smoked seafood unless it is canned or shelf-stable or it is in a cooked dish, such as a casserole.
Raw (unpasteurized) milk
Raw milk is milk from any animal that has not been pasteurized to kill harmful bacteria. Raw milk (also called unpasteurized milk) can carry harmful bacteria (Brucella, Campylobacter, Cryptosporidium, E. coli and Salmonella), including Listeria, and other germs that can make you and your family very sick or can kill you. Although it is possible to get foodborne illness from many kinds of foods, raw milk is one of the riskiest of all — even dairy farms with very good safety practices can contain illness-causing germs. And even if tests on a batch of a farm’s raw milk come back negative, it is no guarantee that the next batch of milk will be free of harmful germs.
Raw milk made into other products, such as soft cheese, ice cream, and yogurt, can also cause dangerous infections. When consuming these products, make sure they are made from pasteurized milk.
Many people believe that foods with little to no processing are better for their health. Many people also believe that small, local farms are better sources of healthy food. However, some types of processing are needed to protect health. One type of processing happens when we cook raw meat, poultry, and fish to make them safe to eat. Similarly, when milk is pasteurized, it is made safe by heating it just long enough to kill disease-causing germs. Most nutrients remain in milk after it is pasteurized.
Pasteurization is the process of heating milk to a high enough temperature for a long enough time to kill illness-causing germs. Pasteurized milk is milk that has gone through this process. The heating process of pasteurization inactivates some enzymes in milk but scientists do not believe these enzymes are important in human health. Some nutrients are somewhat reduced in pasteurized milk, but the U.S. diet generally has plenty of other sources of these nutrients. For example, vitamin C is reduced by pasteurization, but raw milk is not a major source of vitamin C for humans. Many medical and scientific organizations recommend pasteurization for all milk consumed by humans; these include CDC, the Food and Drug Administration, the American Academy of Pediatrics, the American Veterinary Medical Association, the National Association of State Public Health Veterinarians, and others. Most of the nutritional benefits of drinking milk are available from pasteurized milk without the risk of disease that comes with drinking raw milk.
Recommendations for everyone, especially people at higher risk, including infants and young children, pregnant women, older adults, and people with weakened immunity:
- Only consume pasteurized milk and milk products, including soft cheese, ice cream, and yogurt. Look for the word “pasteurized” on the label. If in doubt, don’t buy it!
- Keep milk and milk products refrigerated at 40°F or colder.
What are the symptoms of listeriosis?
Listeriosis can cause a variety of symptoms, depending on the person and the part of the body affected. Listeria can cause fever and diarrhea similar to other foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, depend on whether the person is pregnant.
- Pregnant women: Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
- People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.
People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with Listeria; some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure.
How is listeriosis diagnosed and treated?
Listeriosis is usually diagnosed when a bacterial culture (a type of laboratory test) grows Listeria monocytogenes from a body tissue or fluid, such as blood, spinal fluid, or the placenta.
Listeriosis is treated with antibiotics.
Risk factors for food poisoning
Whether you become ill after eating contaminated food depends on the organism, the amount of exposure, your age and your health. High-risk groups include:
- Older adults. As you get older, your immune system may not respond as quickly and as effectively to infectious organisms as when you were younger.
- Pregnant women. During pregnancy, changes in metabolism and circulation may increase the risk of food poisoning. Your reaction may be more severe during pregnancy. Rarely, your baby may get sick, too.
- Infants and young children. Their immune systems haven’t fully developed.
- People with chronic disease. Having a chronic condition — such as diabetes, liver disease or AIDS — or receiving chemotherapy or radiation therapy for cancer reduces your immune response.
Complications of food poisoning
The most common serious complication of food poisoning is dehydration — a severe loss of water and essential salts and minerals. If you’re a healthy adult and drink enough to replace fluids you lose from vomiting and diarrhea, dehydration shouldn’t be a problem.
Infants, older adults and people with suppressed immune systems or chronic illnesses may become severely dehydrated when they lose more fluids than they can replace. In that case, they may need to be hospitalized and receive intravenous fluids. In extreme cases, dehydration can be fatal.
Some types of food poisoning have potentially serious complications for certain people. These include:
- Listeria monocytogenes. Complications of a listeria food poisoning may be most severe for an unborn baby. Early in pregnancy, a listeria infection may lead to miscarriage. Later in pregnancy, a listeria infection may lead to stillbirth, premature birth or a potentially fatal infection in the baby after birth — even if the mother was only mildly ill. Infants who survive a listeria infection may experience long-term neurological damage and delayed development.
- Escherichia coli (E. coli). Certain E. coli strains can cause a serious complication called hemolytic uremic syndrome. This syndrome damages the lining of the tiny blood vessels in the kidneys, sometimes leading to kidney failure. Older adults, children younger than 5 and people with weakened immune systems have a higher risk of developing this complication. If you’re in one of these risk categories, see your doctor at the first sign of profuse or bloody diarrhea.
Prevention of food poisoning
To prevent food poisoning at home:
- Wash your hands, utensils and food surfaces often. Wash your hands well with warm, soapy water before and after handling or preparing food. Use hot, soapy water to wash utensils, cutting boards and other surfaces you use.
- Keep raw foods separate from ready-to-eat foods. When shopping, preparing food or storing food, keep raw meat, poultry, fish and shellfish away from other foods. When grocery shopping, keep raw meat, poultry, seafood, and their juices away from other foods. Use separate cutting boards and plates for raw meat, poultry, and seafood. Keep raw meat, poultry, seafood, and eggs separate from all other foods in the fridge. This prevents cross-contamination.
- Cook foods to a safe temperature. The best way to tell if foods are cooked to a safe temperature is to use a food thermometer. You can kill harmful organisms in most foods by cooking them to the right temperature. Cook ground meats such as beef and pork to 160° F (71.1° C); steaks, roasts and chops, such as lamb, pork and veal, to at least 145° F (62.8° C). Cook chicken and turkey to 165° F (73.9° C). Cook to at least 165°F for leftovers and casseroles. Make sure fish and shellfish are cooked thoroughly.
- Refrigerate or freeze perishable foods promptly — within two hours of purchasing or preparing them. If the room temperature is above 90° F (32.2° C), refrigerate perishable foods within one hour. Leftovers should be refrigerated at 40°F or colder within 2 hours after preparation. Large cuts of meat, such as roasts or a whole turkey, should be divided into small quantities for refrigeration so they’ll cool quickly enough to prevent bacteria from growing. Keep your refrigerator below 40°F.
- Defrost food safely. Don’t thaw food at room temperature. The safest way to thaw food is to defrost it in the refrigerator. If you microwave frozen food using the “defrost” or “50 percent power” setting, be sure to cook it immediately.
- Throw it out when in doubt. If you aren’t sure if a food has been prepared, served or stored safely, discard it. Food left at room temperature too long may contain bacteria or toxins that can’t be destroyed by cooking. Don’t taste food that you’re unsure about — just throw it out. Even if it looks and smells fine, it may not be safe to eat.
Food poisoning is especially serious and potentially life-threatening for young children, pregnant women and their fetuses, older adults, and people with weakened immune systems.
These individuals should take extra precautions by avoiding the following foods:
- Raw or rare meat and poultry
- Raw or undercooked fish or shellfish, including oysters, clams, mussels and scallops
- Raw or undercooked eggs or foods that may contain them, such as cookie dough and homemade ice cream
- Raw sprouts, such as alfalfa, bean, clover and radish sprouts
- Unpasteurized juices and ciders
- Unpasteurized milk and milk products
- Soft cheeses, such as feta, Brie and Camembert; blue-veined cheese; and unpasteurized cheese
- Refrigerated pates and meat spreads
- Uncooked hot dogs, luncheon meats and deli meats
Food poisoning diagnosis
Food poisoning is often diagnosed based on a detailed history, including how long you’ve been sick, your symptoms and specific foods you’ve eaten. Your doctor will also perform a physical exam, looking for signs of dehydration.
Depending on your symptoms and health history, your doctor may conduct diagnostic tests, such as a blood test, stool culture or examination for parasites, to identify the cause and confirm the diagnosis.
For a stool culture, your doctor will send a sample of your stool to a laboratory, where a technician will try to identify the infectious organism. If an organism is found, your doctor likely will notify your local health department to determine if the food poisoning is linked to an outbreak.
In some cases, the cause of food poisoning can’t be identified.
How to treat food poisoning
There are many different kinds of foodborne diseases and treatment for food poisoning typically depends on the source of the illness, if known, and the severity of your symptoms.
For most people, the illness resolves without treatment within a few days, though some types of food poisoning may last longer.
Illnesses that are primarily diarrhea or vomiting can lead to dehydration if the person loses more body fluids and salts (electrolytes) than they take in.
Treatment of food poisoning may include:
- Replacement of lost fluids. Fluids and electrolytes — minerals such as sodium, potassium and calcium that maintain the balance of fluids in your body — lost to persistent diarrhea need to be replaced. If diarrhea is severe, oral rehydration solution such as Ceralyte, Pedialyte or Oralyte, should be drunk to replace the fluid losses and prevent dehydration. Sports drinks such as Gatorade do not replace the losses correctly and should not be used for the treatment of diarrheal illness. Some children and adults with persistent diarrhea or vomiting may need hospitalization, where they can receive salts and fluids through a vein (intravenously), to prevent or treat dehydration.
- Antibiotics. Your doctor may prescribe antibiotics if you have certain kinds of bacterial food poisoning and your symptoms are severe. Food poisoning caused by listeria needs to be treated with intravenous antibiotics during hospitalization. The sooner treatment begins, the better. During pregnancy, prompt antibiotic treatment may help keep the infection from affecting the baby.
Antibiotics will not help food poisoning caused by viruses. Antibiotics may actually worsen symptoms in certain kinds of viral or bacterial food poisoning. Talk to your doctor about your options.
Adults with diarrhea that isn’t bloody and who have no fever may get relief from taking the medication loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol). Preparations of bismuth subsalicylate (e.g., Pepto-Bismol) can reduce the duration and severity of simple diarrhea. Ask your doctor about these options.
- If diarrhea and cramps occur, without bloody stools or fever, taking an antidiarrheal medication may provide symptomatic relief, but these medications should be avoided if there is high fever or blood in the stools because they may make the illness worse.
Home remedies for food poisoning
Food poisoning often improves without treatment within 48 hours. To help keep yourself more comfortable and prevent dehydration while you recover, try the following:
- Let your stomach settle. Stop eating and drinking for a few hours.
- Try sucking on ice chips or taking small sips of water. You might also try drinking clear soda, clear broth or noncaffeinated sports drinks, such as Gatorade.
- You’re getting enough fluid when you’re urinating normally and your urine is clear and not dark.
- Ease back into eating. Gradually begin to eat bland, low-fat, easy-to-digest foods, such as soda crackers, toast, gelatin, bananas and rice. Stop eating if your nausea returns.
- Avoid certain foods and substances until you’re feeling better. These include dairy products, caffeine, alcohol, nicotine, and fatty or highly seasoned foods.
- Rest. The illness and dehydration can weaken and tire you.
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