Norovirus

Epidemic outbreaks of Acute Diarrheal illness
Most common cause of Viral Gastroenteritis in the world
1. Causes 90% of non-Bacterial Gastroenteritis (and 18% of all Gastroenteritis)
Norwalk Virus
1. Named for a Gastroenteritis outbreak at an elementary school in Norwalk Ohio (1968)
Caliciviridae (Calicivirus)
1. Human Caliciviruses primarily cause acute Viral Gastroenteritis (fecal-oral transmission)
2. Caliciviridae are a family of non-enveloped (naked) RNA Viruses with an icosahedral capsid
3. Caliciviridae are Message Sense RNA Viruses (Positive Stranded, +ssRNA)
  1. Message sense RNA (+ssRNA) are identical to Messenger RNA (mRNA)
  2. Like mRNA, +ssRNA may be immediately translated by host ribosomes into Protein

Taxonomy
1. Family: Caliciviridae
2. Genus: Norovirus
3. Species: Norwalk Virus
Transmission
1. Fecal-oral route (Foodborne Illness or Waterborne Illness)
2. Fomites and surfaces
Precautions
1. Highly contagious
2. Bleach is effective at killing virus on surfaces (but many other disinfectants are not)

Onset: 12 to 48 hours after exposure
Duration: 12 to 60 hours
1. Illness may be prolonged for months in Immunocompromised patients
Systemic symptoms
1. Low grade fever (variably present)
2. Lethargy
3. Weakness
4. Myalgias
5. Malaise
6. Headache
Gastrointestinal symptoms
1. Nausea
2. Projectile Vomiting (esp. children)
3. Watery Diarrhea
4. Abdominal Pain