Parvovirus Infection

Introduction
Clinical manifestations
Investigation
Treatment
Management of pregnant women at risk for parvovirus exposure

Introduction

Human Parvovirus B19 is a small unenveloped virus containing single stranded DNA and is responsible for several clinical syndromes.

Normal transmission is presumably by the respiratory route via droplet aerosol. Most children have encountered the virus by their teenage years but those who escape infection as children are susceptible as adults. Parvovirus can be transmitted across the placenta posing a potential threat to the fetus.

Clinical manifestations

fetal infection - Primary maternal infection has been associated with nonimmune fetal hydrops and intrauterine fetal demise. The pathogenic sequence is transplacental transfer of B19 virus - infection of RBC precursors - arrested RBC production- severe anemia - congestive heart failure - oedema

The overall vertical transmission rate to the fetus is approximately one third.

The attack rate for severe fetal disease (hydrops) is approximately 5% following infection during the first 18 weeks. Infection occurring beyond 18 weeks have been associated with anemia. B 19 virus has been detected in cardiac tissue causing myocarditis, and can also cause fetal hepatitis with severe liver disease. This is a condition managed by a perinatologist

erythema Infectiosum (Fifth disease) - Most common manifestation of B19. A benign, self-limiting exanthematous illness of childhood. The hallmark is a characteristic "slapped cheek" rash. The rash spreads rapidly to the trunk and proximal extremities as a diffuse macular erythema. The palms and soles are spared, and the rash tends to be more prominent on extensor surfaces. Central clearing of macular lesions occurs promptly, giving the rash a lacy, reticulated appearance. The rash resolves spontaneously without desquamation but tends to wax and wane over 1- 3 weeks.
individuals with chronic hemolytic conditions may experience transient red cell aplastic crises
arthritis and arthralgia of small joints may complicate fifth disease or be the sole clinical manifestation of infection
chronic infection may occur in the immunocompromised host causing chronic anemia or complete marrow suppression

Investigation

Measure serum IgG and IgM levels. IgM levels appear by day 3 of an acute infection and begin to fall by 2 to 3 months after infection. IgG appears a few days after IgM and may persist for years.

Viral antigens may be directly detected in tissues by radioimmunoassay, ELISA, immunofluorescence, in situ nucleic acid hybridization, or PCR.

Treatment

Treatment is generally supportive.

There are case reports of successful use of Intravenous gamma globulin (IVIG) in patients with severe hematologic disorders. IVIG prophylaxis may be considered in immunocompromised patients exposed to B19 infection, however, IVIG is not currently recommended for prophylaxis in pregnancy.

Management of pregnant women at risk for parvovirus exposure

Measurement of serum IgG and IgM levels may be useful to determine those at risk or acutely infected after B19 exposure. These tests should generally limited to pregnant women clearly at increased risk for acute B19 exposure during the first 18 weeks of gestation.

Consultation with an infectious disease physcian is reccommended.

References

Bishara J. Freij and John L. Sever. Textbook of Neonatology. Gordon B. Avery (5th Ed). Philadelphia: Lippincott Williams & Wilkins, 1999

Stoll, B. J., Weiseman, L. E. Infections in perinatology. Clin. Perinatol. 24:1, 1997.

Brown KE, Young NS. Human parvovirus B19 infection in infants and children. Adv Pediatr Infect Dis 1998; 13:101.

Sandra K. Burchett. Manual of neonatal care. John P. Cloherty (4^th Ed). Philadelphia: Lippincott-Raven, 1998.

Samuel P.Gotoff. Textbook of pediatrics. Behrman (16^th Ed) Philadelphia: W. B. Saunders Company

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