PEDBASE.org - The Pediatric Database - Detailed information of CONGENITAL PARVOVIRUS B19

CONGENITAL PARVOVIRUS B19

DEFINITION:

A contagious infectious disease caused by Parvovirus B19 resulting in an asymptomatic infant or fetal death.

1. Antenatal (in utero)

1. Primary Maternal Infection

33% vertical transplacental transmission rate
infection may occur after symptomatic or asymptomatic maternal infection during pregnancy
maternal viremia with transplacental passage - 9% risk of fetal death if infection is acquired in the first 20 weeks in a seronegative mother
risk of fetal loss is similar when B19 is acquired in the 1st or 2nd trimester but is less in the 3rd - substantial risk of fetal loss in the 2nd trimester

1. Horizontal Transmission

direct human-to-human contact
- teachers, day-care workers, paediatric health-care providers at risk
- respiratory, possibly by droplet aerosol
by blood or blood products

infection most common in school age children and >50% of adults have serologic evidence of past infection:
- 10% of cases - less than 5 years
- 70% of cases - 5 to 15 years
- 20% of cases - greater than 15 years
secondary attack rate in susceptible household members is about 50%
in healthy individuals, B19 infection usually causes a transient RBC aplasia that is neither symptomatic nor detected - the B19 virus tends to replicate in erythroid progeniter cells inhibiting erythropoiesis -> anemia

1975 - human parvovirus B19 (single-strand DNA) first discovered
1981 - B19 virus not associated with a disease until 1981 when found to be associated with aplastic crisis (transient RBC aplasia) in a patient with sickle cell anemia
1983 - associated with erythema infectiosum (Fifth Disease)
1984 - found to be a source of intrauterine infection
1985 - associated with some forms of acute arthritis

normal healthy infant
no congential anomalies have been associated with a B19 infection during pregnancy, i.e., no teratogenic effect
no evidence of persistent neurodevelopmental abnormality at 1 year of age

stillbirth or spontaneous abortion with:
- nonimmune hydrops fetalis
- hemolytic anemia
- myocarditis
fetal infection occurs within 1-10 weeks of maternal infection

gold standard
B19 virus grows in explant cultures of bone marrow cells isolated from persons with hemolytic anemia

B19 IgM antibody tests
- monoclonal antibodies with radioimmunoassays and ELISA
- both IgG and IgM are present at or soon after the onset of the illness and reach peak titres within the first 30 days
- IgM antibody titres begin to fall 30-60 days after the onset of the illness and become undetectable by 60-90 days
- IgM may not be present at birth

to detect B19 antigen or nucleic acid
- nucleic acid hybridization probes
- viral detection by direct or immune EM
- PCR

intrauterine therapy with percutaneous umbilical vein blood transfusion with packed RBC's for management of hydrops is experimental
aplastic crisis - oxygen therapy, blood transfusions

pregnant women if exposed to B19 can be tested serologically and monitered with fetal ultrasound and alpha-FP determinations

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