What are the management and treatment options for a pregnant woman diagnosed with fifth (erythema infectiosum) disease?

Management of Fifth Disease (Erythema Infectiosum) During Pregnancy

Pregnant women diagnosed with fifth disease (erythema infectiosum) should be evaluated for immune status with IgG testing and undergo fetal surveillance with serial ultrasound examinations if susceptible, with referral to a tertiary care center if fetal hydrops develops. 1, 2

Understanding Fifth Disease in Pregnancy

Fifth disease is caused by Parvovirus B19 (B19V) infection and presents unique concerns during pregnancy:

• Vertical transmission occurs in 33-51% of maternal infections, potentially causing fetal anemia, heart failure, and non-immune hydrops fetalis 2
• The infection follows seasonal patterns, with higher prevalence in late winter and early spring in temperate climates 2
• Women at increased risk include mothers of school-age children and those working in educational settings such as schools, nurseries, and kindergartens 2

Management Algorithm for Fifth Disease in Pregnancy

Step 1: Immune Status Evaluation

• Test for Parvovirus B19 IgG and IgM antibodies 1
• If IgG positive (immune) and IgM negative: No risk to fetus, routine prenatal care can continue 1
• If IgG negative (non-immune) and IgM positive or if both are positive: Proceed to fetal surveillance 1, 2

Step 2: Fetal Surveillance for Non-Immune or Acutely Infected Mothers

• Implement serial ultrasound examinations every 1-2 weeks for 8-12 weeks after exposure or confirmed infection 1, 3
• Monitor specifically for signs of:
  • Fetal anemia
  • Hydrops fetalis (fluid accumulation in fetal compartments)
  • Cardiac dysfunction 2, 3

Step 3: Management Based on Fetal Assessment

• Normal ultrasound findings: Continue surveillance until risk period passes (approximately 12 weeks post-exposure) 3
• Abnormal findings (signs of hydrops or anemia): Refer to a tertiary care center with maternal-fetal medicine specialists 1, 3

Step 4: Tertiary Care Interventions (if needed)

• Intrauterine fetal blood sampling to assess degree of anemia 3
• Intrauterine transfusion for severe fetal anemia 3
• These interventions have been shown to improve perinatal outcomes in affected fetuses 2

Important Considerations and Pitfalls

• The overall risk of fetal complications from maternal parvovirus B19 infection is relatively low, occurring in approximately 3-5% of infected pregnancies 2, 3
• Routine screening is not universally recommended but may be considered during endemic periods or for women with occupational exposure 2
• Misdiagnosis is common as the classic "slapped cheek" rash of fifth disease may be absent or subtle in adults 4
• No specific antiviral treatment exists for parvovirus B19 infection; management focuses on fetal surveillance and intervention if complications develop 3
• The critical period of concern is primarily the first 20 weeks of pregnancy, when the fetus is most vulnerable to the effects of the virus 3

Counseling Points for Pregnant Women

• Reassure that while vertical transmission is common (33-51%), the risk of serious fetal complications is low (3-5%) 2, 3
• Emphasize the importance of adherence to the ultrasound surveillance schedule 1
• Discuss preventive measures, including good hand hygiene and potentially avoiding high-risk environments during outbreaks if non-immune 2
• Explain that accurate identification and treatment of affected fetuses has been shown to improve outcomes 2