Norovirus Overview

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Questions and Answers

What is the primary mode of transmission for noroviruses?

Primarily fecal-oral transmission (correct)

Airborne transmission from respiratory droplets

Vector-borne transmission through insects

Direct contact with infected individuals

Which serotype is most commonly associated with human norovirus infections?

Geno-group I

Geno-group III

Geno-group II (correct)

Geno-group IV

Which characteristic is NOT true regarding noroviruses?

They do not have a polymerase within the virion.

They possess an enveloped structure. (correct)

They are approximately 35-39 nm in diameter.

They are stable in the environment.

What is a common clinical feature associated with norovirus infections?

Sudden onset of diarrhea and vomiting Signup and view all the answers

Which of the following statements is true regarding norovirus outbreaks?

Vomit from infected individuals can spread the virus airborne. Signup and view all the answers

What time frame is typical for symptoms to manifest after exposure to norovirus?

12-48 hours post-exposure Signup and view all the answers

How many virus particles are estimated to be needed to start a large norovirus outbreak?

10-100 particles Signup and view all the answers

Which of the following is a misperception about the outcomes of norovirus infection?

Bloody stools are common in all cases. Signup and view all the answers

What is true about the infectiousness of the virus described?

Infectiousness may last up to 2 weeks. Signup and view all the answers

Which method is not an efficient technique for laboratory diagnosis of the virus?

Culturing in a lab setting Signup and view all the answers

Which group is most likely to experience severe symptoms associated with the virus?

Very young children and the elderly Signup and view all the answers

What is the main treatment approach for the virus's symptoms?

Symptomatic treatment with fluids Signup and view all the answers

What characteristic feature is associated with Astroviruses?

They have a star-shaped surface morphology. Signup and view all the answers

Which of the following actions is recommended to prevent foodborne outbreaks?

Effective hand washing and careful food processing. Signup and view all the answers

Which of the following statements about Norovirus is true?

It can cause severe illness in the elderly and immunocompromised people. Signup and view all the answers

Astroviruses are associated with which type of illness?

Endemic gastroenteritis Signup and view all the answers

What is the primary cause of childhood mortality related to acute infectious gastroenteritis?

Viral agents such as rotavirus Signup and view all the answers

Which feature is characteristic of the reoviridae family?

Double-stranded RNA genome Signup and view all the answers

What is the typical structure of a reovirus particle?

Icosahedral symmetry with a double-layered capsid Signup and view all the answers

How does rotavirus primarily spread among populations?

Fecal-oral route through contaminated surfaces Signup and view all the answers

What is a leading method for diagnosing rotavirus infection in a laboratory setting?

PCR (Polymerase Chain Reaction) Signup and view all the answers

In treating symptoms of diarrhea caused by viral agents, which of the following is commonly emphasized?

Oral rehydration solutions to prevent dehydration Signup and view all the answers

What is a common symptom associated with an infection caused by enteric viruses?

Acute onset of vomiting and diarrhea Signup and view all the answers

Norovirus is often associated with outbreaks in which type of environment?

School dormitories and cruise ships Signup and view all the answers

Study Notes

Noroviruses

Resemble picornaviruses in size and structure, non-enveloped with an icosahedral shape, 35-39 nm in diameter, and possess positive-sense RNA.
Contains multiple serotypes with five identified genogroups; most human infections stem from genogroup II.
Highly infectious, requiring as few as 10 viral particles for significant outbreaks. Primarily transmitted via fecal-oral route and airborne particles from vomit.
Commonly associated with gastroenteritis outbreaks related to contaminated water, food, and shellfish.
Known for stability in the environment and recognized as the leading cause of non-bacterial gastroenteritis in the USA.

Clinical Features

Sudden onset of symptoms 12-48 hours post-ingestion, including vomiting, diarrhea, nausea, and abdominal cramps, particularly in children.
Blood in stools is rare; low-grade fever may be present in up to one-third of patients.
Certain individuals may show central nervous system involvement, but many cases may remain asymptomatic despite antibody detection.
Young children, the elderly, and immunocompromised individuals often experience more severe symptoms.
Infectiousness can last up to 2 weeks, with no long-term carriers identified. Antibodies provide short-term protection against re-infection with the same strain.

Diagnosis

No efficient culture techniques available; detection methods include electron microscopy and RT-PCR for viral genomic material in stool or vomit samples, alongside ELISA tests.

Treatment and Prevention

Symptomatic treatment focuses on hydration, using oral rehydration or intravenous fluids.
Preventive measures include effective hand washing, safe food handling practices, and drinking water purification to mitigate outbreaks.

Astroviruses

Small RNA viruses (ss +) with non-enveloped structure characterized by a star-shaped morphology, measuring 28-30 nm in diameter.
Associated with endemic gastroenteritis, predominantly in young children and neonates, with symptoms such as diarrhea, nausea, vomiting, fever, malaise, and abdominal pain.
Responsible for approximately 10% of gastroenteritis cases, presenting a similar clinical picture to rotavirus and adenovirus infections.

Overall Context on Acute Infectious Gastroenteritis

A widespread illness affecting all age groups globally, significantly impacting childhood morbidity and mortality, especially in developing regions with around 2 million annual deaths among children due to diarrheal diseases.
Symptoms typically include sudden vomiting and/or diarrhea, often accompanied by fever, nausea, abdominal cramps, anorexia, and malaise.

Reoviridae Family

Named from the abbreviation of respiratory enteric orphan virus; initially no associated diseases were identified.
Includes several members: Orthoreoviruses (not serious in humans), Rotavirus (notable for gastroenteritis), Orbiviruses, and Coltiviruses (causing Colorado tick fever).
Orbiviruses and Coltiviruses are prevalent arboviruses spread via arthropods.

General Characteristics of Reoviridae

Virion size ranges from 60-80 nm with a double-stranded segmented RNA genome consisting of 10-12 segments.
The capsid features two layered shells with an icosahedral symmetry, and its wheel-like structure is reflected in the name 'rota' (Latin for wheel).

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Description

This quiz explores the characteristics and properties of noroviruses. It covers aspects such as their structure, serotypes, and the factors contributing to their spread. Prepare to test your knowledge about these common yet impactful viruses.