Parvovirus B19 Flashcards

1
Q

Define

A

Erythema infectiosum (AKA ‘fifth disease’) caused by parvovirus B19 (a small ssDNA virus)

Incubation period 4-20 days; infective from 10 days prior of rash until 1 day after appearance of rash

Risk period if vertically transmitted <20w GA; low risk >20w

Aetiology – transmission by aerosol route, also blood-borne

Risk factors – children and susceptible adults

Epidemiology – common, 60% immunity in adults by age 20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Signs and symptoms

A

In the young child / mother:

  • Asymptomatic in most cases
  • Rash, malaise, fever, arthralgia, transient aplastic crisis (however, 25% asymptomatic)
  • Rash – commonly ‘slapped cheek’ appearance (erythema infectiosum)
  • Infant – coryzal symptoms, headache, rash

In the neonate / antepartum:

  • Produces mild self limiting infection in adults but can cause spontaneous miscarriage or IUD if transmitted to the foetus
  • B19 crosses placenta (4-20w GA) and destroys RBCs  hydrops fetalis  10% infant mortality
  • Treat with intrauterine transfusions
  • No other CNS damage so if treated with transfusions, many infants are completely fine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Investigations

A

(if exposed after 20w, no investigations are needed as very low risk):

Routine screening not recommended

Viral DNA PCR - MOST accurate

  • Use maternal serum/blood + resp samples

IgM and IgG  if -ve IgG and -ve IgM, re-check in 1m [if +ve IgM B19  serial USS]

  • Infection must be confirmed by atleast 2 samples

USS  foetal anomaly scan 4 weeks after onset of illness, then serial scans in 2-week intervals until 30/40

Rubella serology (similar presentation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Management

A

Maternal and infant  self-limiting (clears up in 3w) - supportive treatment with paracetamol and plenty of fluids

Intrauterine

  • If confirmed infection of parvovirus B19, refer to foetal medicine specialist within 4 weeks for monitoring foetal growth and assessing for complications
  • The main risk of foetal parvovirus infection is FOETAL HYDROPS
  • Serial USS and Doppler assessment
    • Start at 4 weeks post-infection or at 16 weeks, repeating every 1-2 weeks until 30 weeks gestation
  • If there is evidence of foetal hydrops on USS- REFER to tertiary centre for IU erythrocyte transfusion
    • A hydropic foetus may recover spontaneously or may require IU transfusion 
  • If anaemia is treated by intrauterine transfusion, foetus can make a complete recovery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Complications

A

miscarriage (15%), foetal hydrops (3%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly