Parvovirus Flashcards

1
Q

Parvovirus

Types
Other names

Transmission routes

A

Single stranded DNA virus

Parvovirus B19
Erythema infectiosum
Slapped cheek disease
Fifth Disease

Contact - hand to mouth
Respiratory secretions

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2
Q

Parvovirus

Pathogenesis

A

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

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3
Q

Parvovirus

Risk of transmission

A

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

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4
Q

Parvovirus

Features of maternal infection

A

Asymptomatic 20-30%

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

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5
Q

Parvovirus

Features of neonatal infection

A

Exposed:

  1. 4-1% fetal loss if <20weeks
  2. 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

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6
Q

Parvovirus

Investigations

A

• 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

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7
Q

Parvovirus

Management

A

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

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8
Q

Parvovirus

Prevention

A

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

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