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Norovirus

Updated : February 1, 2024





Background

Globally, norovirus is a prevalent cause of acute onset gastroenteritis. Norovirus has surpassed rotavirus as the most prevalent cause of gastroenteritis in children in developed nations with rotavirus immunization programs.

Infection with norovirus frequently causes nausea, vomiting, and diarrhea.These may cause clinically significant dehydration and require hospitalization. Norovirus has significant financial impacts in developed countries in addition to its clinical effects.

Epidemiology

An estimated 21 million cases of gastrointestinal disease in the US annually occur due to norovirus. The precise number of instances may surpass the estimate since individuals with mild conditions may consider not seeking medical attention. Approximately 60% of acute gastroenteritis cases in the US are believed to be caused by norovirus, which is also accountable, according to the CDC, for 400,000 visits to emergency rooms and 71,000 hospitalizations annually. An analysis of previous norovirus outbreaks revealed that food-related transmission was the most frequent cause of the disease.

Food contamination during production or contamination caused by food service staff during preparation is two possible causes of food-related transmission. Raw fruits and vegetables, oysters, and seafood are among the foods that are most likely to be infected with the norovirus. There are several diverse settings where outbreaks frequently occur. Gastroenteritis epidemics are known to be brought on by norovirus in hospitals and other healthcare institutions.

Although anybody can have norovirus, individuals who are immunocompromised and at the extremes of age are more at risk of suffering adverse effects. According to specific research, individuals with community-acquired norovirus infection had a 30-day death rate of 7%, putting them at an elevated risk of deadly results. Similar to adults, newborns are more likely to experience significant side effects, including necrotizing enterocolitis. Young children experience the most significant prevalence of norovirus across all age groups.

Anatomy

Pathophysiology

According to studies, the human gut has a diverse range of cell types involved in the multifaceted complexity of norovirus infection. The single layer of intestinal epithelial cells known as enterocytes is the main cell type lining the human gut. There are plenty of immune cells lying deep within the enterocytes. Dendritic cells, B cells, and macrophages are among the immune cells in which the norovirus infects and replicates. Theoretically, noroviruses can enter human hosts without going via enterocytes.

Postulated entry points include lymphoid follicles, M cells in the gut, and specialized cells covering Peyer patches.  M cells do not release mucus and have no microvilli, which makes it easier for the norovirus to infiltrate the host and invade immune cells. Other findings, however, indicate that norovirus may directly infect enterocytes lining the gut lumen, despite the lack of conclusive data.

Additionally, studies are being conducted to determine how the host’s pre-existing gut microbiota affects norovirus infection. It has been hypothesized that norovirus interacts with gut microorganisms to boost infection and replication. The average time from viral infection to the onset of clinical symptoms is 1-2 days, and norovirus symptoms typically resolve in 1 to 3 days.

Etiology

Norovirus is a highly contagious virus that causes inflammation of the stomach and intestines, leading to symptoms such as diarrhea, vomiting, and abdominal pain. It is one of the leading causes of gastroenteritis. Norovirus is a member of the Caliciviridae family and is classified as a calicivirus. It is a small, non-enveloped virus with a single-stranded, positive-sense RNA genome. There are several genotypes of norovirus, and new strains can emerge through genetic mutation.

It is transmitted through the fecal-oral route by contaminated food, water, or surfaces with fecal matter that contains the virus. It can also be transmitted through close contact with an infected person, such as through saliva. Outbreaks often occur in settings where people are in close proximity to each other, such as in hospitals, nursing homes, schools, and cruise ships.

The virus can be challenging to control in these settings because it is highly contagious and can survive for long periods on surfaces. Preventing the spread of norovirus involves good hygiene practices, such as washing hands frequently with soap and water, thoroughly cooking seafood, and properly storing and handling food. Vaccines are currently being developed to prevent norovirus infection but are not yet available for widespread use.

Genetics

Prognostic Factors

Norovirus is usually a self-limiting illness. In most cases, the symptoms of norovirus can be managed with supportive care such as hydration and rest. It is essential to consume fluids to replace the lost due to diarrhea and vomiting, as dehydration can occur quickly in people with norovirus infection.

Norovirus can sometimes lead to serious complications, particularly in individuals who are immunocompromised or have underlying medical conditions. These complications can include dehydration, malnutrition, and electrolyte imbalances.

Clinical History

Physical Examination

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

Media Gallary

References

https://www.ncbi.nlm.nih.gov/books/NBK513265/

Norovirus

Updated : February 1, 2024




Globally, norovirus is a prevalent cause of acute onset gastroenteritis. Norovirus has surpassed rotavirus as the most prevalent cause of gastroenteritis in children in developed nations with rotavirus immunization programs.

Infection with norovirus frequently causes nausea, vomiting, and diarrhea.These may cause clinically significant dehydration and require hospitalization. Norovirus has significant financial impacts in developed countries in addition to its clinical effects.

An estimated 21 million cases of gastrointestinal disease in the US annually occur due to norovirus. The precise number of instances may surpass the estimate since individuals with mild conditions may consider not seeking medical attention. Approximately 60% of acute gastroenteritis cases in the US are believed to be caused by norovirus, which is also accountable, according to the CDC, for 400,000 visits to emergency rooms and 71,000 hospitalizations annually. An analysis of previous norovirus outbreaks revealed that food-related transmission was the most frequent cause of the disease.

Food contamination during production or contamination caused by food service staff during preparation is two possible causes of food-related transmission. Raw fruits and vegetables, oysters, and seafood are among the foods that are most likely to be infected with the norovirus. There are several diverse settings where outbreaks frequently occur. Gastroenteritis epidemics are known to be brought on by norovirus in hospitals and other healthcare institutions.

Although anybody can have norovirus, individuals who are immunocompromised and at the extremes of age are more at risk of suffering adverse effects. According to specific research, individuals with community-acquired norovirus infection had a 30-day death rate of 7%, putting them at an elevated risk of deadly results. Similar to adults, newborns are more likely to experience significant side effects, including necrotizing enterocolitis. Young children experience the most significant prevalence of norovirus across all age groups.

According to studies, the human gut has a diverse range of cell types involved in the multifaceted complexity of norovirus infection. The single layer of intestinal epithelial cells known as enterocytes is the main cell type lining the human gut. There are plenty of immune cells lying deep within the enterocytes. Dendritic cells, B cells, and macrophages are among the immune cells in which the norovirus infects and replicates. Theoretically, noroviruses can enter human hosts without going via enterocytes.

Postulated entry points include lymphoid follicles, M cells in the gut, and specialized cells covering Peyer patches.  M cells do not release mucus and have no microvilli, which makes it easier for the norovirus to infiltrate the host and invade immune cells. Other findings, however, indicate that norovirus may directly infect enterocytes lining the gut lumen, despite the lack of conclusive data.

Additionally, studies are being conducted to determine how the host’s pre-existing gut microbiota affects norovirus infection. It has been hypothesized that norovirus interacts with gut microorganisms to boost infection and replication. The average time from viral infection to the onset of clinical symptoms is 1-2 days, and norovirus symptoms typically resolve in 1 to 3 days.

Norovirus is a highly contagious virus that causes inflammation of the stomach and intestines, leading to symptoms such as diarrhea, vomiting, and abdominal pain. It is one of the leading causes of gastroenteritis. Norovirus is a member of the Caliciviridae family and is classified as a calicivirus. It is a small, non-enveloped virus with a single-stranded, positive-sense RNA genome. There are several genotypes of norovirus, and new strains can emerge through genetic mutation.

It is transmitted through the fecal-oral route by contaminated food, water, or surfaces with fecal matter that contains the virus. It can also be transmitted through close contact with an infected person, such as through saliva. Outbreaks often occur in settings where people are in close proximity to each other, such as in hospitals, nursing homes, schools, and cruise ships.

The virus can be challenging to control in these settings because it is highly contagious and can survive for long periods on surfaces. Preventing the spread of norovirus involves good hygiene practices, such as washing hands frequently with soap and water, thoroughly cooking seafood, and properly storing and handling food. Vaccines are currently being developed to prevent norovirus infection but are not yet available for widespread use.

Norovirus is usually a self-limiting illness. In most cases, the symptoms of norovirus can be managed with supportive care such as hydration and rest. It is essential to consume fluids to replace the lost due to diarrhea and vomiting, as dehydration can occur quickly in people with norovirus infection.

Norovirus can sometimes lead to serious complications, particularly in individuals who are immunocompromised or have underlying medical conditions. These complications can include dehydration, malnutrition, and electrolyte imbalances.

https://www.ncbi.nlm.nih.gov/books/NBK513265/