Calici/Norovirus

Question 1

Norovirus structure & classification

Answer 1

Family: Calicivirus
Genus: Norovirus
Species: Norwalk virus

(+)ssRNA NON enveloped

Baltimore: IV

10 genogroups & 52 genotypes

Most common human virus: Genogroup 2, genotype 4

Question 2

Sapovirus

Answer 2

Family: Caliciviridae
Genus: Sapovirus

(+)ss RNA NON ENVELOPED

very similar to Noro in terms of clinical picture.

Incubation 1-4 days

Diagnostics: RT-PCR not widely available plus commercial primers do not pick up all genotypes.

Biofire GI panel
EM is an option.

No specific treatment or vaccine.

Question 3

Norovirus incubation & viral shedding period

Answer 3

1-2 days

Shedding - 4 weeks from symptom onset

Question 4

Noro pathophysiology

Answer 4

Diarrhoea caused by malabsorption of D-xylose & fat.

Question 5

Atypical noro infection

Answer 5

Seizures & encephalitis

Question 6

Noro treatment

Answer 6

One drug which stands out is an anti-protozoal one called nitazoxanide which improves symptoms but viral shedding and outcomes were not that great.

Other options available are use of Oral Ig, IVIG, ribavirin, vitamin A and use of mTOR inhibitors.

Favipravir alone or in combination with nitazoxanide has also been used.

There has been a recent use reported of nasoduodenal Privigen which avoid gastric inactivation of product and showed good results.