Caliciviridae

Question 1

Characteristics of Caliciviruses

Answer 1

Non-enveloped, single stranded RNA

Feco-oral transmission

Question 2

Examples of caliciviruses that cause gastroenteritis

Answer 2

Noroviruses

Sapoviruses

Question 3

Clinical findings of caliciviruses

Answer 3

Norovirus is the most important case of epidemic gastroenteritis in adults

Incubation period of 24-48 hours

Clinical course is brief (12-60 hours)

Non-bacterial epidemic gastroenteritis is characterized by:

• Absence of bacterial pathogens
• Gastroenteritis wit rapid onset and recovery with relatively mild symptoms
• A highly communicable disease that spreads regardless of age and geography

Question 4

Symptoms of Noroviruses

Answer 4

Diarrhea
vomiting
low grade fever
abdominal cramps

viral shedding may persist for a month

No sequelae reported

Question 5

Lab diagnosis

Answer 5

Rt- PCR is used to detect viral specimen in faeces and vomit

Electron microscopy can be used to view specimen in stool

Question 6

Immunity to caliciviruses

Answer 6

Antibody protection developed during infection is short term and against paticular serotype

Question 7

Epidemiology of caliciviruses (Norovirus)

Answer 7

The virus is usually associated with waterborne, foodborne and shell-fish associated gastroenteritis
May also include person to person transmission through fomites or aerosolization of contaminated body fluids (Vomit and faeces)
Low infectious dosage (10 viruses required at least )

Question 8

Control of calicivirus (Noroviruses)

Answer 8

Survives chlorine and in steamed oysters

Can also survive heating to 60 degrees

Question 9

Treatment

Answer 9

No vaccine
Effective hand washing
Careful procesing of shellfish and other foods
Careful disposal of stool
Proper purification of pools and drinking water