Parvovirus B19

Snapshot

• A 25-year-old woman presents to the emergency room for painful joints. She has had pain in her bilateral hands and wrists for the past few days. She also had a low-grade fever and mild upper respiratory symptoms. She is 14-weeks pregnant and has had good prenatal care. She works as a kindergarten teacher. On physical exam, the joint in her hands are slightly swollen and tender. A fetal ultrasound shows hydrops fetalis.

Introduction

• Classification
  • parvovirus B19 
    • non-enveloped, linear, single-stranded DNA virus 
    • causes a variety of diseases
      • aplastic crisis in patients with red blood cell disorders 
      • pure red blood cell aplasia in adults
      • rheumatoid arthritis-like symptom in adults
      • erythema infectiosum (fifth disease) in children
      • hydrops fetalis in fetuses if pregnant women are infected
    • transmission via respiratory droplets
• Epidemiology
  • incidence
    • highest in winter and spring
  • demographics
    • children > adults
  • risk factors
    • sickle cell disease
    • thalassemia
    • hereditary spherocytosis
    • close proximity to others (e.g., school or daycare centers)
• Pathogenesis 
  • infects red blood cells through the P antigen
  • viral replication in bone marrow causes the death of erythroid progenitor cells
• causes hydrops fetalis in fetuses due to severe fetal anemia

Presentation

• Symptoms
  • prodrome with flu-like symptom
  • hydrops fetalis and fetal death in pregnant women
  • polyarthropathy
    • small joints (e.g., hands)
• Physical exam
  • erythema infectiosum 
    • first rash appears as slapped cheeks  
• subsequent rash is an erythematous maculopapular rash on the trunk and limbs, which may appear reticular or lacy 

Studies

• Labs
  • parvovirus-specific immunoglobulin M
  • detection of parvovirus on polymerase chain reaction
  • anemia
  • low or absent reticulocyte 
• Making the diagnosis
  • based on clinical presentation
• may be confirmed with laboratory studies

Differential

• Measles 
  • distinguishing factors
    • confluent maculopapular rash without slapped cheeks rash
    • Koplik spots on buccal mucosa
• Rubella 
  • distinguishing factor
• non-confluent maculopapular rash that spreads from face to body

Treatment

• Management approach
  • mainstay of treatment is supportive care
• Conservative
  • supportive care
    • indication
      • all patients
    • modalities
      • analgesics
      • hydration
• Medical
  • non-steroidal anti-inflammatory drugs
    • indication
• polyarthropathy

Complications

• Myocarditis
• Behcet syndrome
• Aplastic crisis