Parvovirus Flashcards
Parvovirus
Types
Other names
Transmission routes
Single stranded DNA virus
Parvovirus B19
Erythema infectiosum
Slapped cheek disease
Fifth Disease
Contact - hand to mouth
Respiratory secretions
Parvovirus
Pathogenesis
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
Parvovirus
Risk of transmission
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
Parvovirus
Features of maternal infection
Asymptomatic 20-30%
Flu-like illness
Headache
Rash - facial, “slapped cheek”
Arthralgia
Parvovirus
Features of neonatal infection
Exposed:
- 4-1% fetal loss if <20weeks
- 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
Parvovirus
Investigations
• 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
Parvovirus
Management
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
Parvovirus
Prevention
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