Parvovirus

Question 1

Parvovirus

Types
Other names

Transmission routes

Answer 1

Single stranded DNA virus

Parvovirus B19
Erythema infectiosum
Slapped cheek disease
Fifth Disease

Contact - hand to mouth
Respiratory secretions

Question 2

Parvovirus

Pathogenesis

Answer 2

Replicates in rapidly dividing cellse.g.erthryoblastprecursors, targets P antigen.
Leads to haemolysis.

Infection <20weeks more prone to anaemia as this is when erythropoiesis mainly hepatic

Question 3

Parvovirus

Risk of transmission

Answer 3

40% women susceptible

Exposure at home and susceptible up to 50%
–> <20% risk infection in pregnancy
Exposure at childcare/school and susceptible up to 20-30%
–> 8-12% risk infection in pregnancy
Exposure in community and susceptible up to 20%
–> <8% risk infection in pregnancy

50% vertical transmission

Question 4

Parvovirus

Features of maternal infection

Answer 4

Asymptomatic 20-30%

Flu-like illness
Headache
Rash - facial, “slapped cheek”
Arthralgia

Question 5

Parvovirus

Features of neonatal infection

Answer 5

Exposed:

0. 4-1% fetal loss if <20weeks
1. 05-0.1% fetal death from hydrops or its treatment

Confirmed infection:
Fetal anaemia
3% hydrops - average onset 5weeks
- 33% death without transfusion
- 6% death with transfusion

10% additional fetal loss if <20weeks

No increased risk of congenital anomalies or long term adverse effects

Question 6

Parvovirus

Investigations

Answer 6

• IgM
+ve within 1-3weeks of exposure, persists for 2- 3months
Can have false +ve if IgG remains -ve despite repeat

• IgG
-ve = susceptible. Repeat 2-4weeks if symptomatic or exposed, treat as +ve if becomes +ve.
+ve in isolation = immune

• IgG avidity - consider
High = infection >3months prior
Low = infection more recent <3months

• Routine screening not recommended
• No association with alpha-fetoprotein despite previously thought

• Fetal infection: Fetal blood sample or amniocentesis -> PCR for B19

Question 7

Parvovirus

Management

Answer 7

Counsel about exposure risks

Offer serological testing (IgM, IgG +/- avidity)

Do not offer TOP

USS 1-2weekly for 12 weeks

Refer to FMed if signs of anaemia/hydrops

FMed to confirm fetal infection – Amnio or cordocentesis and PCR

MVA PSV – if >1.5MoM for intrauterine blood transfusion

Ongoing USS surveillance

Question 8

Parvovirus

Prevention

Answer 8

No vaccine
No treatment to prevent fetal infection or damage
Not practical to prevent at home exposure
During an epidemic pregnant women not recommended to exclude from work - childcare or teaching (as epidemic may be very long)
Infected children do not require isolation