Norovirus is the most common cause of acute gastroenteritis in the United States. Each year, it causes 19-21 million illnesses and contributes to 56,000-71,000 hospitalizations and 570-800 deaths. Norovirus is also the most common cause of foodborne-disease outbreaks 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.
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
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.
Most people with norovirus illness get better within 1 to 3 days.
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).
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.
Practice proper 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.
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.
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.
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 3 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.
Listeriosis, a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes. The disease primarily affects older adults, pregnant women, newborns, and adults with weakened immune systems However, rarely, people without these risk factors can also be affected.
A person with listeriosis usually has fever and muscle aches, sometimes preceded by diarrhea or other gastrointestinal symptoms. Almost everyone who is diagnosed with listeriosis has “invasive” infection, in which the bacteria spread beyond the gastrointestinal tract. The symptoms vary with the infected person:
- Pregnant women: Pregnant women typically experience fever and other non-specific symptoms, such as fatigue and 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.
Listeriosis can present in different ways. In older adults and people with immunocompromising conditions, septicemia and meningitis are the most common clinical presentations. Pregnant women may experience a fever and other non-specific symptoms, such as fatigue and aches, followed by fetal loss or bacteremia and meningitis in their newborns . Immunocompetent people may experience acute febrile gastroenteritis or no symptoms .
People get listeriosis by eating food contaminated with Listeria monocytogenes. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. However, healthy people may consume contaminated foods without becoming ill. People at risk can prevent listeriosis by avoiding certain higher-risk foods and by handling and storing food properly.
Listeria monocytogenes is commonly found in soil and water. Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin, such as meats and dairy products.
Most human infections follow consumption of contaminated food . Rare cases of hospital-acquired transmission have been reported in newborns.
When Listeria bacteria get into a food processing factory, they can live there for years, sometimes contaminating food products . The bacterium has been found in a variety of foods, such as:
- Uncooked meats and vegetables
- Unpasteurized (raw) milk and cheeses as well as other foods made from unpasteurized milk
- Cooked or processed foods, including certain soft cheeses, processed (or ready-to-eat) meats, and smoked seafood
Listeria are killed by cooking and pasteurization. However, in some ready-to-eat meats, such as hot dogs and deli meats, contamination may occur after factory cooking but before packaging or even at the deli counter. Also, be aware that Mexican-style cheeses (such as queso fresco) made from pasteurized milk and likely contaminated during cheese-making have caused Listeria infections.
Unlike most bacteria, Listeria can grow and multiply in some foods in the refrigerator.
For symptomatic patients, diagnosis is confirmed only after isolation of Listeria monocytogenes from a normally sterile site, such as blood, spinal fluid (in the setting of nervous system involvement), or amniotic fluid/placenta (in the setting of pregnancy).
Listeriosis is treated with antibiotics. A person in a higher-risk category (pregnant woman, older adults, and people with weakened immune systems) who experiences fever and other non-specific symptoms, such as fatigue and aches, within 2 months of eating contaminated food should seek medical care and tell the physician or health care provider about eating the contaminated food. The incubation period for Listeria ranges from 3 to 70 days and averages 21 days.
If a person has eaten food contaminated with Listeria and does not have any symptoms, most experts believe that no tests or treatment are needed.
Hepatitis A is an acute infectious disease of the liver caused by the hepatitis A virus. The time between infection and symptoms, in those who develop them, is between 15 and 50 days. When there are symptoms they typically last eight weeks and may include: nausea, vomiting, diarrhea, yellow skin, fever, and abdominal pain. Around 10–15% of people experience a recurrence of symptoms during the six months after the initial infection Acute liver failure may rarely occur with this being more common in the elderly.
Hepatitis A is usually spread by eating or drinking food or water contaminated with infected feces. Food related outbreaks are usually traced back to an infected food handler. Shellfish which have not been sufficiently cooked is a possible source as is produce contaminated during growing harvesting or processing. The virus may also be spread through close contact with an infectious person. While children often do not have symptoms when infected they are still able to infect others. After a single infection a person is immune for the rest of their life. Diagnosis requires blood testing as the symptoms are similar to those of a number of other diseases.
The hepatitis A vaccine is effective for prevention. Other preventative measures include hand washing and properly cooking food. There is no specific treatment, with rest and medications for nausea or diarrhea recommended on an as needed basis. Infections usually resolve completely and without ongoing liver disease. Treatment of acute liver failure, if it occurs, is with liver transplantation.
Salmonellosis is an infection with bacteria called Salmonella. Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons, the 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 and 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.
Many different kinds of illnesses can cause diarrhea, fever, or abdominal cramps. Determining that Salmonella is the cause of the illness depends on laboratory tests that identify Salmonella in the stool of an infected person.
Salmonella gastrointestinal infections usually resolve within 7 days and most do not require treatment other than oral fluids. Persons with severe diarrhea may require rehydration with intravenous fluids. Antibiotic therapy can prolong the duration of excretion of non-typhoidal Salmonella and is recommended only for patients with severe illness (e.g., those with severe diarrhea, high fever, bloodstream infection, or who need hospitalization) or those at risk of severe disease or complications, including young infants, older adults (over 65 years old) and immunocompromised persons.
Salmonella live in the intestinal tracts of humans and other animals, including birds. Salmonella are usually transmitted to humans by eating foods contaminated with animal feces. Contaminated foods usually look and smell normal. Contaminated foods are often of animal origin, such as beef, poultry, milk, or eggs, but any food, including vegetables, may become contaminated. Thorough cooking kills Salmonella. Food may also become contaminated by the hands of an infected food handler who did not wash hands with soap after using the bathroom.
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. Poultry and meat, including hamburgers, should be well-cooked, not pink in the middle. 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. Hands should be washed before handling food, and between handling different food items.
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.
Escherichia coli (E. coli) bacteria normally live in the intestines of people and animals. Most E. coli are harmless and actually are an important part of a healthy human intestinal tract. However, some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract. The types of E. coli that can cause diarrhea can be transmitted through contaminated water or food, or through contact with animals or persons.
A source of contracting E. coli is consuming food that has been contaminated by animal manure. E.coli outbreaks have been traced back to consumption of contaminated ground beef. Leafy vegetables that are contaminated during growing or harvesting have also been the source of outbreaks.
Symptoms of E. Coli infection are abdominal pain and severe cramps, followed by diarrhea. This normally occurs within 2 to 5 days of eating contaminated food however the incubation period can range from 1 to 10 days. . Medical attention can treat symptoms and reduce the chance of serious complications such Hemolytic Uremic Syndrome.
E.coli infections are diagnosed by testing of a stool sample.
Meats, especially ground beef should be thoroughly cooked before eating. Any surfaces or utensils that uncooked meat has touched should be thoroughly cleaned to avoid cross contamination. Wash your hands often and especially after handling uncooked foods that may be contaminated.