Norovirus infection epidemiology and demographics: Difference between revisions
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==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
'''Norovirus is the leading cause of acute gastroenteritis in all age groups in the United States.''' | |||
Each year, norovirus— | |||
* causes about 21 million cases of acute gastroenteritis, and | |||
* contributes to about 70,000 hospitalizations and 800 deaths, mostly among young children and older adults | |||
Also, 16% of all acute gastroenteritis in the community is caused by norovirus, and 12% of acute gastroenteritis cases that get outpatient care are caused by norovirus. | |||
People can get norovirus illness at any time during the year. But, it is most common in the winter. Also, there can be 50% more norovirus illness in years when there is a new strain of the virus going around. | |||
'''Norovirus is the leading cause of foodborne illness in the United States.''' It is responsible for— | |||
* 58% of domestically-acquired foodborne illnesses, and | |||
* 50% of foodborne disease outbreaks due to known agents. | |||
Each year, it costs about $2 billion in the United States for healthcare and lost productivity from foodborne illness caused by norovirus. | |||
Most foodborne outbreaks of norovirus illness are caused by eating food that was just contaminated by a food handler. However, widespread outbreaks of norovirus can also be caused by food, such as oysters, raspberries, and leafy greens, that were contaminated at their source. | |||
Waterborne outbreaks of norovirus illness also occur in community settings. This is often caused by sewage contaminated wells and untreated recreational water. | |||
[[CDC]] currently does not conduct active [[disease surveillance|surveillance]] to monitor [[outbreak]]s of [[gastroenteritis]] caused by [[norovirus]]es. [[outbreak|Outbreaks]] are reported to CDC's Viral Gastroenteritis Section, Respiratory and Gastroenteric Viruses Branch, Division of Viral Diseases, National Center for Immunization and Respiratoiry Diseases (NCIRD) when states send specimens for testing or sequencing, or outbreaks are reported directly by states to the electronic database (eFORS) maintained by the Foodborne Diarrheal Diseases Branch. | [[CDC]] currently does not conduct active [[disease surveillance|surveillance]] to monitor [[outbreak]]s of [[gastroenteritis]] caused by [[norovirus]]es. [[outbreak|Outbreaks]] are reported to CDC's Viral Gastroenteritis Section, Respiratory and Gastroenteric Viruses Branch, Division of Viral Diseases, National Center for Immunization and Respiratoiry Diseases (NCIRD) when states send specimens for testing or sequencing, or outbreaks are reported directly by states to the electronic database (eFORS) maintained by the Foodborne Diarrheal Diseases Branch. | ||
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However, any food that is served raw or handled after being cooked can get contaminated. Norovirus outbreaks have also been caused by contaminated water from sewage in wells and recreational water, such as pools. | However, any food that is served raw or handled after being cooked can get contaminated. Norovirus outbreaks have also been caused by contaminated water from sewage in wells and recreational water, such as pools. | ||
===Reporting=== | |||
Currently, state, local, and territorial health departments are not required to report individual cases of norovirus illness to a national surveillance system. They may not know about such cases because most hospitals and doctor’s offices do not have capability to test for norovirus. The virus is usually diagnosed only when an outbreak happens. | |||
Health care providers should report all outbreaks of acute gastroenteritis, including suspected outbreaks of norovirus, to the appropriate state, local or territorial health department. | |||
====Definition of a Norovirus Outbreak==== | |||
An outbreak of norovirus is defined as an occurrence of two or more similar illnesses resulting from a common exposure. | |||
Health departments are encouraged to report all suspected and confirmed norovirus outbreaks through the National Outbreak Reporting System (NORS) and CaliciNet. | |||
===Surveillance Systems=== | |||
====NORS==== | |||
NORS was launched by CDC in 2009 to collect information on outbreaks of foodborne, waterborne, and enteric disease that spread from person-to-person, animals, environmental surfaces, and other or unknown ways. Public health agencies can report all outbreaks of gastroenteritis, including norovirus illness, through this web-based system. This information is used to determine where norovirus outbreaks commonly occur, how the virus is spread, and specific food or water sources involved. In turn, this helps with identifying the best ways to prevent and control norovirus illness and outbreaks. | |||
====CaliciNet==== | |||
CDC developed CaliciNet in 2009. It is a network of public health and food regulatory laboratories that submit norovirus sequences identified from outbreaks into a national database. The information is used to link norovirus outbreaks that may be caused by common sources (such as food), monitor trends, and identify emerging norovirus strains. As of February 2012, public health laboratories in 25 states have been certified by the CDC to participate in CaliciNet. States that are not yet certified may contribute through designated CaliciNet outbreak support centers, including the CDC. | |||
====Other Surveillance Systems==== | |||
CDC is using New Vaccine Surveillance Network (NVSN) and Fooborne Diseases Active Surveillance Network (FoodNet) to do norovirus testing on patients with gastroenteritis. This will help generate new estimates of norovirus illness and monitor trends over time. | |||
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Revision as of 16:42, 26 December 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Epidemiology and Demographics
Norovirus is the leading cause of acute gastroenteritis in all age groups in the United States.
Each year, norovirus—
- causes about 21 million cases of acute gastroenteritis, and
- contributes to about 70,000 hospitalizations and 800 deaths, mostly among young children and older adults
Also, 16% of all acute gastroenteritis in the community is caused by norovirus, and 12% of acute gastroenteritis cases that get outpatient care are caused by norovirus.
People can get norovirus illness at any time during the year. But, it is most common in the winter. Also, there can be 50% more norovirus illness in years when there is a new strain of the virus going around.
Norovirus is the leading cause of foodborne illness in the United States. It is responsible for—
- 58% of domestically-acquired foodborne illnesses, and
- 50% of foodborne disease outbreaks due to known agents.
Each year, it costs about $2 billion in the United States for healthcare and lost productivity from foodborne illness caused by norovirus.
Most foodborne outbreaks of norovirus illness are caused by eating food that was just contaminated by a food handler. However, widespread outbreaks of norovirus can also be caused by food, such as oysters, raspberries, and leafy greens, that were contaminated at their source.
Waterborne outbreaks of norovirus illness also occur in community settings. This is often caused by sewage contaminated wells and untreated recreational water.
CDC currently does not conduct active surveillance to monitor outbreaks of gastroenteritis caused by noroviruses. Outbreaks are reported to CDC's Viral Gastroenteritis Section, Respiratory and Gastroenteric Viruses Branch, Division of Viral Diseases, National Center for Immunization and Respiratoiry Diseases (NCIRD) when states send specimens for testing or sequencing, or outbreaks are reported directly by states to the electronic database (eFORS) maintained by the Foodborne Diarrheal Diseases Branch.
Each year, norovirus causes about 21 million cases of acute gastroenteritis (inflammation of the stomach or intestines or both) and contributes to about 70,000 hospitalizations and 800 deaths, mostly among young children and the elderly. One can get norovirus illness at any time during the year. But, it is most common in the winter. Also, there can be 50% more norovirus illness in years when there is a new strain of the virus going around.
Outbreaks
Most noroviruses that infect humans belong to genogroups GI and GII.[1] Noroviruses from Genogroup II, genotype 4 (abbreviated as GII.4) account for the majority of adult outbreaks of gastroenteritis and often sweep across the globe.[2] Recent examples include US95/96-US strain, associated with global outbreaks in the mid- to late-1990s, Farmington Hills virus associated with outbreaks in Europe and the United States in 2002 and in 2004, and Hunter virus was associated with outbreaks in Europe, Japan and Australasia. In 2006, there was another large increase in NoV infection around the globe.[3]
Most outbreaks of norovirus illness happen when infected people spread the virus to others. But, norovirus can also spread by consuming contaminated food or water and touching things that have the virus on them. Healthcare facilities, including nursing homes and hospitals, are the most commonly reported places for norovirus outbreaks in the United States and other industrialized countries. Nearly two-thirds of all norovirus outbreaks reported in the United States occur in long-term care facilities. Outbreaks of norovirus illness have also occurred in restaurants, cruise ships, schools, banquet halls, summer camps, and even at family dinners. These are all places where people often eat food handled or prepared by others. In fact, norovirus is the leading cause of illness from contaminated food in the United States. About 50% of all outbreaks of food-related illness are caused by norovirus. Foods that are commonly involved in outbreaks of norovirus illness are:
- Leafy greens (such as lettuce),
- Fresh fruits, and
- Shellfish (such as oysters).
However, any food that is served raw or handled after being cooked can get contaminated. Norovirus outbreaks have also been caused by contaminated water from sewage in wells and recreational water, such as pools.
Reporting
Currently, state, local, and territorial health departments are not required to report individual cases of norovirus illness to a national surveillance system. They may not know about such cases because most hospitals and doctor’s offices do not have capability to test for norovirus. The virus is usually diagnosed only when an outbreak happens.
Health care providers should report all outbreaks of acute gastroenteritis, including suspected outbreaks of norovirus, to the appropriate state, local or territorial health department.
Definition of a Norovirus Outbreak
An outbreak of norovirus is defined as an occurrence of two or more similar illnesses resulting from a common exposure.
Health departments are encouraged to report all suspected and confirmed norovirus outbreaks through the National Outbreak Reporting System (NORS) and CaliciNet.
Surveillance Systems
NORS
NORS was launched by CDC in 2009 to collect information on outbreaks of foodborne, waterborne, and enteric disease that spread from person-to-person, animals, environmental surfaces, and other or unknown ways. Public health agencies can report all outbreaks of gastroenteritis, including norovirus illness, through this web-based system. This information is used to determine where norovirus outbreaks commonly occur, how the virus is spread, and specific food or water sources involved. In turn, this helps with identifying the best ways to prevent and control norovirus illness and outbreaks.
CaliciNet
CDC developed CaliciNet in 2009. It is a network of public health and food regulatory laboratories that submit norovirus sequences identified from outbreaks into a national database. The information is used to link norovirus outbreaks that may be caused by common sources (such as food), monitor trends, and identify emerging norovirus strains. As of February 2012, public health laboratories in 25 states have been certified by the CDC to participate in CaliciNet. States that are not yet certified may contribute through designated CaliciNet outbreak support centers, including the CDC.
Other Surveillance Systems
CDC is using New Vaccine Surveillance Network (NVSN) and Fooborne Diseases Active Surveillance Network (FoodNet) to do norovirus testing on patients with gastroenteritis. This will help generate new estimates of norovirus illness and monitor trends over time.
Shown below is a graph that illustrates outbreaks of acute gastroenteritis in 30 states from January 2007 through April 2010. On average, there were nearly 3 times as many norovirus outbreaks (143 per month) as non-norovirus outbreaks (50 per month) and the number of norovirus outbreaks increased dramatically during the winter months. A new virus strain (GII.4 New Orleans) that first appeared in October 2009 did not lead to more outbreaks.
Shown below is a graph that illustrates the setting of 1,518 confirmed norovirus outbreaks in the U.S. from 2010 to 2011: Long-term Care Facility 59% (889 Outbreaks); Restaurants 8% (123 Outbreaks); Party & Event 7% (99 Outbreaks); Hospital 4% (65 Outbreaks); School 4% (64 Outbreaks); Cruise Ship 4% (55 Outbreaks); Other & Unknown 14% (223 Outbreaks).
Epidemiologic Criteria
Epidemiologic criteria have been proposed for use in determining whether an outbreak of gastroenteritis is of viral origin. Although quite specific, these criteria are not very sensitive, and therefore the possibility of a viral etiology should not be discarded if the criteria are not met. Kaplan's criteria for this purpose are as follows:
- A mean (or median) illness duration of 12 to 60 hours
- A mean (or median) incubation period of 24 to 48 hours
- More than 50% of people with vomiting
- No bacterial agent previously found
Developing Countries
Epidemiological data from developing countries about the importance of norovirus in pediatric diarrhea are limited. Recently, in Nicaragua, it has been observed that norovirus is responsible for 11% of the diarrhea cases occurring in children less than five years of age at community level and 15% of the moderate to severe cases requiring intravenous rehydration.[4]
In the Guangdong province of the People's Republic of China, the Provincial Health Department said on December 17, 2010, that it had confirmed 429 cases of norovirus infection in the November 2010 outbreak in Conghua, Guangzhou, but no one died from it.[5]
References
- ↑ Vinjé J, Green J, Lewis DC, Gallimore CI, Brown DW, Koopmans MP (2000). "Genetic polymorphism across regions of the three open reading frames of "Norwalk-like viruses"". Arch. Virol. 145 (2): 223–41. doi:10.1007/s007050050020. PMID 10752550.
- ↑ Noel J, Fankhauser RL, Ando T, Monroe SS, Glass RI (2000). "Identification of a distinct common strain of "Norwalk-like viruses" having a global distribution". J. Infect. Dis. 179 (6): 1334–44. doi:10.1086/314783. PMID 10228052.
- ↑ Tu ET, Bull RA, Greening GE, Hewitt J, Lyon MJ, Marshall JA, McIver CJ, Rawlinson WD, White PA (2008). "Epidemics of gastroenteritis during 2006 were associated with the spread of norovirus GII.4 variants 2006a and 2006b". Clin. Infect. Dis. 46 (3): 413–20. doi:10.1086/525259. PMID 18177226.
- ↑ Bucardo F, Nordgren J, Carlsson B, Paniagua M, Lindgren PE, Espinoza F, Svensson L., "Pediatric norovirus diarrhea in Nicaragua", J. Clin. Microbiology, 46: 8 (August 2008), pp. 2573–80.
- ↑ Norovirus infects 429 people in Guangzhou (CNTV reports)