a) Norovirus is the leading cause of sporadic gastroenteritis in people of all ages. It is estimated that noroviruses account for 10% to 15% of severe gastroenteritis cases in children younger than 5 years, and for 9% to 15% of cases of mild to moderate diarrhea in people of all ages (Hall et al, 2011).

a) In the United States, an estimated 5.5 million norovirus infections (estimated range, 3.2 million to 8.3 million cases of foodborne illness) occur annually, accounting for 58% of all foodborne illnesses. This results in approximately 0.03% of patients (range, 8097 to 23,323; mean, 14,663) requiring hospitalization and less than 0.1% of these illnesses resulting in death (range, 84 to 237 deaths; mean, 149) (Center for Food Safety and Applied Nutrition (CFSAN), 2012).
b) Noroviruses are the most common cause of gastroenteritis outbreaks worldwide. Outbreaks often occur in the following settings: long-term care facilities, other healthcare facilities, restaurants, catered events, schools and other institutions, and cruise ships (Hall et al, 2011).
c) About 30% to 50% of norovirus outbreaks occur in closed facilities (eg, hospitals, retirement centers, nursing homes). During 2000-2001 the CDC estimates that 28% of norovirus outbreaks occurred in restaurants or catered events, 16% on cruise ships, and 8% in daycare centers (Said et al, 2008). One outbreak was reported at a catered conference in a hospital setting (Vinnard et al, 2012).
d) Duration of outbreaks is generally longer in healthcare facilities than in other settings. In a meta-analysis of outbreaks in closed settings published through June 2008, outbreaks in hospitals lasted a mean of 19 days (range: 6 to 92 days), in nursing homes the mean duration of an outbreak was 16 days (range: 3 to 44 days) and in non-healthcare settings the mean duration of outbreaks was 7 days (range: 1 to 26 days) (Harris et al, 2008).

a) Most foodborne infections develop from fecal-oral transmission in one of two ways. Primary contamination develops when food is contaminated prior to harvest, for example shellfish grown in sewage contaminated waters or vegetables or soft fruits sprayed or irrigated with contaminated water. Secondary contamination occurs at harvest, or during food processing or serving, and results from use of contaminated water, contaminated preparations surfaces, or transmission of infection from a food handler (Tuan Zainazor et al, 2010).
b) Food handlers have been implicated as the most common source of contamination leading to outbreaks, in those cases where the source of the outbreak could be identified (Dreyfuss, 2009).
c) Commonly implicated foods include prepared foods such as salads, sandwiches and baked goods, and raw or poorly cooked meat or seafood. Fruits and vegetables that are usually consumed without heating are also common sources (Tuan Zainazor et al, 2010). Sandwiches, potato chips, and ice were implicated in one outbreak (Vinnard et al, 2012).
d) Fruits and vegetables may be contaminated prior to harvest from use of irrigation water contaminated with feces, or organic fertilizers. Bivalve shellfish can become contaminated from fecally contaminated seawater. Other seafood is generally secondarily contaminated during processing or serving (Tuan Zainazor et al, 2010).

a) Studies show that there is an increase in norovirus outbreaks by up to 25% in the colder months of the year and a decrease in the warmer months (Dreyfuss, 2009).

a) Coinfection with norovirus and bacteria causing gastroenteritis has been reported, particularly in cases of traveler's diarrhea (Ajami et al, 2010). Coinfection with other gastroenteritis causing viruses has also been reported in both outbreaks and sporadic cases (Liu et al, 2010).

a) Fatalities are rare and occur almost exclusively in the elderly. A study in England and Wales suggested that norovirus infection might be associated with about 80 deaths a year in patients over the age of 65 (Harris et al, 2008).

1) Noroviruses are nonenveloped, single-stranded RNA viruses in the genus Norovirus and the family Caliciviridae.

1) In the United States, an estimated 5.5 million norovirus infections (estimated range, 3.2 million to 8.3 million cases of foodborne illness) occur annually, accounting for 58% of all foodborne illnesses. This results in approximately 0.03% of patients (range, 8097 to 23,323; mean, 14,663) requiring hospitalization and less than 0.1% of these illnesses resulting in death (range, 84 to 237 deaths; mean, 149). Noroviruses are the leading cause of sporadic gastroenteritis, and the leading cause of gastroenteritis outbreaks worldwide. It is extremely contagious. Infections are common, but fatalities are very rare and generally only occur in patients with severe underlying health problems. Approximately, 10% of patients are ill enough to seek medical attention. Common settings for outbreaks include long-term care facilities, other healthcare facilities, restaurants, catered events, schools and other institutions, and cruise ships. Outbreaks generally peak in cold weather.

1) Norovirus affects people of all ages. Outbreaks involve people in settings that encourage person-to-person spread (ie, semiclosed environments, military, schools, recreational activities). Children under age 5 and adults over age 65, as well as patients with significant underlying medical problems, are at higher risk for complications such as dehydration requiring hospitalization.

1) The exact pathogenic pathway of infection is unknown. Noroviruses cause the inflammation of the stomach and the small and large intestines.

1) ACUTE SYMPTOMS
2) CHRONIC SYMPTOMS
3) ROUTE OF EXPOSURE
4) TIME TO ONSET
5) DURATION

1) Care is symptomatic and supportive. Administer antiemetics, and intravenous or oral fluids to prevent dehydration.

1) Always use standard precautions with all patients. Meticulous hand hygiene is imperative for patients, visitors and staff to control transmission. Wash hands well with soap and water for one minute, rinse for 20 seconds and dry with a disposable paper towel. Hands should be washed after eating or drinking, using the bathroom, or contact with patients. An alcohol-based hand sanitizer may not be effective against noroviruses. Use gloves, gown, mask and/or face shield when caring for ill patients depending on the anticipated exposure.

1) Acutely ill patients should be isolated as much as possible during the acute stage of illness and for 24 to 72 hours after recovery, during the peak period of viral shedding. Do not share equipment between patients. Use gown, gloves and mask or face shield for all interactions that may involve contact with a patient or contaminated areas of the patient's environment. Isolate ill patients to single rooms, or if that is not possible cohort ill patients together. Do not allow visits by sick individuals. Provide different toilet facilities for ill and non-ill patients. Remove supplies from a room before an infected patient is admitted.

1) Clean spill with detergent to remove particulate material and then with a hospital approved disinfectant. Chemical disinfectants (ie, at least a 1:50 sodium hypochlorite:water solution) should be used on potentially contaminated environmental surfaces, particularly in bathrooms or on high-touch surfaces like doorknobs, light switches, tables, counter tops, keyboards, and hand rails, every shift. Clean bathrooms every shift. Clean common areas, and staff rooms, including refrigerators. Clean rooms every 24 hours and at patient discharge. Clean floors with approved disinfectant, change cleaning solution and mop head every 3 rooms. Clean rooms that have housed patients with vomiting and/or diarrhea last, change the mop head and solution after cleaning a room that housed an infected patient. Remove and replace curtains, if soiled or contaminated.

1) HOME CRITERIA: The vast majority of patients with self-limited vomiting and diarrhea who can tolerate oral fluids can be managed at home.
2) OBSERVATION CRITERIA: Patients with persistent vomiting, severe diarrhea and those who can not tolerate oral fluids should be referred to a healthcare facility for treatment with antiemetics and intravenous hydration.
3) ADMISSION CRITERIA: Patients with severe dehydration, electrolyte abnormalities, and those with vomiting that persists despite therapy, may require hospital admission. Infants, the elderly, and patients with significant underlying health problems are more likely to require admission.
4) CONSULT CRITERIA: Consult an infections disease specialist and the local health department in the event of a significant outbreak, to help identify the source of exposure and reduce further transmission.

a) Illness is typically self-limiting. Severe nausea and vomiting are usually the first sign of illness. Other symptoms include nonbloody watery diarrhea and abdominal cramps. Low-grade fever, headache and myalgias may also develop. Dehydration, hyponatremia, hypokalemia, acute renal insufficiency and mild elevations in aminotransferases may develop in patients with severe gastroenteritis. Up to 30% of patients with norovirus infection are asymptomatic.

a) Norovirus may exacerbate inflammatory bowel disease, but evidence is inconclusive.

a) Transmission can occur from person-to-person, or by foodborne or waterborne spread. Spread from person-to-person may be through the fecal-oral route, ingestion of aerosolized vomitus, or indirectly via fomites or contaminated surfaces. Foodborne spread is most commonly from infected food handlers during food preparation or service. It may also occur from agricultural contamination with human waste or during food processing. Well water can become contaminated from leaking of septic tanks or sewage systems. Recreational water can become contaminated from inadequate chlorination. Commonly implicated foods include: prepared foods such as salads, sandwiches and baked goods, and raw or poorly cooked meat or seafood, and fruits and vegetables that are usually consumed without heating.

a) Generally 24 to 48 hours (median: 33 to 36 hours) after exposure; onset times within 12 hours have been reported.

a) Symptoms last 12 to 60 hours (mean, 24 to 48 hours) in healthy adults and older children, may resolve within 72 to 96 hours in the elderly, very young children, or hospitalized patients; non-specific symptoms (eg, headache, thirst, vertigo) may last up to 19 days.

1) Low grade fever develops in some patients (Hall et al, 2011).

1) Hypotension might develop in patients with severe volume loss from vomiting and diarrhea, but is not common.

1) Tachycardia might develop in patients with severe volume loss from vomiting and diarrhea, but is not common.

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

1) WITH POISONING/EXPOSURE

A) Patients with severe dehydration, electrolyte abnormalities, and those with vomiting that persists despite therapy, may require hospital admission. Infants, the elderly, and patients with significant underlying health problems are more likely to require admission.

A) The vast majority of patients with self-limited vomiting and diarrhea who can tolerate oral fluids can be managed at home.

A) Consult an infections disease specialist and the local health department in the event of a significant outbreak, to help identify the source of exposure and reduce further transmission.

A) Patients with persistent vomiting, severe diarrhea and those who can not tolerate oral fluids should be referred to a healthcare facility for treatment with antiemetics and intravenous hydration.

1) Care is symptomatic and supportive. Administer antiemetics, and intravenous or oral fluids to prevent dehydration.

1) Unfortunately, no single infection control method has been shown to shorten the duration of outbreaks, and outbreaks in healthcare facilities tend to last the longest (Harris et al, 2010). The following infection control measures are generally recommended.

1) Always use standard precautions with all patients. Meticulous hand hygiene is imperative for patients, visitors and staff to control transmission. Wash hands well with soap and water for one minute, rinse for 20 seconds and dry with a disposable paper towel (Said et al, 2008). Hands should be washed after eating or drinking, using the bathroom, or contact with patients. An alcohol-based hand sanitizer may not be effective against noroviruses (Liu et al, 2010). Use gloves, gown, mask and/or face shield when caring for ill patients depending on the anticipated exposure.

1) Acutely ill patients should be isolated as much as possible during the acute stage of illness and for 24 to 72 hours after recovery, during the peak period of viral shedding. Do not share equipment between patients. Use gown, gloves and mask or face shield for all interactions that may involve contact with patient or contaminated areas of the patient's environment. Isolate ill patients to single rooms, or if that is not possible cohort ill patients together. Do not allow visits by sick individuals. Provide different toilet facilities for ill and non-ill patients (Heijne et al, 2009). Remove supplies from a room before an infected patient is admitted (Said et al, 2008).
2) INFECTED HEALTHCARE WORKERS: In one outbreak that occurred among hospital personnel attending a conference, infected employees were instructed to stay home until 72 hours after symptoms resolved, and the environment was decontaminated rapidly. This resulted in successful prevention of secondary outbreaks or infections (Vinnard et al, 2012).

1) Clean spill with detergent to remove particulate material and then with a hospital approved disinfectant. Chemical disinfectants (ie, at least a 1:50 sodium hypochlorite:water solution) should be used on potentially contaminated environmental surfaces, particularly in bathrooms or on high-touch surfaces like doorknobs, light switches, tables, counter tops, keyboards, and hand rails, every shift. Clean bathrooms every shift. Clean common areas, and staff rooms, including refrigerators. Clean rooms every 24 hours and at patient discharge. Clean floors with approved disinfectant, change cleaning solution and mop head every 3 rooms. Clean rooms that have housed patients with vomiting and/or diarrhea last, change the mop head and solution after cleaning a room that housed an infected patient. Remove and replace curtains if soiled or contaminated (Said et al, 2008).