Rotaviruses

Question 1

Characteristics of rotaviruses

Answer 1

Family: Reoviridae

Segmente double stranded RNA

Virus resembles a wheel

Seven serogroups (A-G)

Group A causes gastroenteritis in children

Question 2

Structure of rotaviruses

Answer 2

Naked, icosahedral

Outer capsid proteins VP4 and VP7 carry epitopes important in neutralizing activity with VP7 (gylcoprotein) proteins the most common

Involved in virus neutralization and hemagglutination

Question 3

Effects of chelating agents

Answer 3

Inactivated by chelating agents afer incubation or freeing with
MgCl
CaCl
NaCl
 15 minutes at 50 degrees

Question 4

Effects of physical/ chemical agents

Answer 4

Most effective : 95% ethanol
Formlin and Lysol are also effective
Shown to survive chlorine treatment in community water treatment
Resistant to commonly used hard-surface disinfectants

Question 5

Epidemiology

Answer 5

Transmission: Feco-oral and shed in vomit (Very transmissible)

Infects nearly all children under 3 years

Nosocomial Infections common

In west, occurs in winter

Severe dehydration may result and could be fatal

Question 6

Epidemiology II

Answer 6

Adults are infected but rarely show symptoms
Subtype A is common in Ghana ( Type C has been detected in the North)

Group A: Most common cause of hospitalization

Group B: Outbreaks in China

Group C: Associated with sporadic cases and occasional outbreaks of diarrheal illness in children

*B and C Not important cases of hospitalization
Maximum incidence of rotaviruses gastroenteritis is common at age 6-24 months

Question 7

Pathogenesis of rotavirus

Answer 7

Viral shedding occurs from 2-21 days in healthy individuals but may be prolonged with malnutrition

Ingestion => Infects
cells of the villi of the small intestine (multiply in the cytoplasm of enterocytes) => villi atrophy and cells die=> Damaged cells on villi are released by immature crypt cells ( Crypt cells are non-absorbing ) => Damaged cells line the lumen of the intestine => inability to absorb sodium and glucose leads to diarrhoea=> excrete in stool
** May take 3-8 weeks for function to be restored

Question 8

Symptoms of rotaviruses

Answer 8

Incubation of 1-3 days
Typical symptoms are watery diarrhea, fever, abdominal pain and vomiting leading to dehydration
In children loss of electrolytes and fluids may be fatal

Question 9

Diagnosis of rotavirus

Answer 9

Viral detection in stool by ELISA

Antibody titre in blood