MYVR-GI-CALICIVIRUSES

• Family = Caliciviridae

  • important agents of viral gastroenteritis in humans
  • the most significant member is Norwalk virus.

  Four Genera

  • Norovirus = Norwalk viruses
  • Sapovirus = Sapporo-like viruses
  • Lagovirus = rabbit hemorrhagic disease virus
  • Vesivirus = vesicular exanthem virus of swine, feline calicivirus, and marine viruses found in pinnipeds, whales, and fish
• NORWALK VIRUS

  • small single-stranded RNA, round viruses of 27-30nm in diameter.
  • It is the common cause of infectious gastroenteritis.
  • incubation period of 24–48 hours

  MOT

  • Food borne (common)
  • Water borne
  • Person-person transmission = can be significant
• NORWALK PATHOGENESIS

  • Onset is rapid, and the clinical course is brief, lasting 12–60 hours
  • Symptoms include = Diarrhea, Nausea, Vomiting, Low-grade fever, Abdominal cramps, Headache, Malaise
  • Antibody develops during the illness and is usually protective on a short-term basis against reinfection with the same agent.
  • Treatment is supportive, depending on the symptoms manifested during infections of the Norwalk virus
• NORWALK LAB DX

  • Since Norovirus and Sapovirus cannot be detected in culture, it relies on immune electron microscopy and RT-PCR
  • ELISA immunoassays based on recombinant virus-like particles can detect antibody responses, with a fourfold sapovirus greater rise in IgG antibody titer in acute and convalescent-phase sera indicative of a recent infection
• NORWALK LAB DX

  • RT- PCR – the most used diagnostic test/assay for Norovirus because it detects the viral RNA and can be used to detect stools, vomit and environmental samples.
  • Stool - best sample to detect Norovirus. The stool will be collected should be from patients with acute illness or within 48-72 hours after the onset of the symptoms.
  • In some cases, stool can be collected from 2 weeks after the recovery.
• SAPOVIRUS

  • small virus that can range from 32- 35 nm in diameter
  • It causes diarrheagenic viruses distinguished by a cup-shaped morphology.
  • It is called Sapovirus – originally discovered in Sapporo, Japan in 1977
  • It is called Norwalk – outbreak during 1968 in Norwalk, Ohayo
  • Treatment is supportive based on the clinical symptoms
  • There is no vaccine!
• SAPOVIRUS MANAGEMENT & PREVENTION

  • Effective handwashing – most important method to prevent transmission
  • Proper disposal – stool
  • Containment and disinfection of soiled areas embedding can help decrease the viral spread
  • Careful processing of food and education of food handlers
  • Purification of drinking water and swimming pool