Norovirus

Background

Microbiology

• Member of the Caliciviridae family of positive-sense single-stranded RNA viruses

Epidemiology

• Most common cause of gastroenteritis worldwide
• More common during winter months
• Antibodies from prior infection do not indicate immunity from future infection

Clinical Manifestations

• Incubation period of 24 to 48 hours
• Causes viral gastroenteritis, with nausea and vomiting followed by profuse watery diarrhea
• Illness lasts 12 to 72 hours
• May have low-grade fevers

Diagnosis

• Usually diagnosed clinically
• Antigen detection with enzyme immunoassays
• Stool PCR, which has higher sensitivity and specificity

Management

• Supportive care and appropriate isolation and outbreak management

Outbreak Management

Kaplan criteria

• Identify outbreaks of gastroenteritis caused by norovirus without specific viral testing1
• The criteria are:
  • Vomiting in more than half of affected patients
  • Mean or median incubation period between 24 and 48 hours
  • Mean or median duration of illness between 12 and 60 hours
  • No bacterial pathogen identified in stool