Parvovirus B19

Diagnosis

Indications for Testing

  • In most patients, clinical presentation is adequate for diagnosis
  • Typical presentation in pregnant females – either rash or arthritis
  • Development of aplastic anemia in immunocompromised patient

Laboratory Testing

  • Antibody testing
    • B19 IgM and IgG antibodies may remain negative in immunocompromised patients or patients presenting with transient aplastic crisis
    • By the time rash or polyarthropathy occurs in immunocompetent patients, viremia is usually cleared and serum antibodies can be used to confirm the clinical diagnosis
    • Appearance of an IgM antibody response normally occurs 7-14 days after the onset of disease
      • IgM antibodies remain detectable 2-3 months after infection
    • Past infection documented by IgG antibodies – IgG antibodies remain detectable for life
  • PCR testing
    • More sensitive than antibody testing
    • In serum samples, positive result indicates ongoing acute or persistent infection
    • In bone marrow samples, positive result indicates acute or remote infection
  • Confirmation of parvovirus infection in pregnancy mandates followup with testing of fetus for development of hemolytic disease

Differential Diagnosis

Clinical Background

Parvovirus B19 is a member of the Erythrovirus family, so named because of its tropism for erythroid precursor cells.

Epidemiology

  • Prevalence
    • 15% of preschool children – seropositive
    • 50% of young adults – seropositive
    • 85% of elderly – seropositive
  • Incidence – peak in late winter, early spring
  • Age – peak is 5-15 years
  • Transmission
    • Respiratory droplets
    • Blood products

Organism

  • Small, single-stranded DNA virus
  • Lacks lipid envelope – resistant to heat and detergent inactivation
  • Targets rapidly growing erythroid progenitor cells

Risk Factors

  • Immunodeficiency disorder
  • Pregnancy

Clinical Presentation

  • Many parvovirus infections asymptomatic – particularly in children
  • Erythema infectiosum (EI) or fifth disease
    • Classically presents in school-aged children
    • EI is a benign, self-limited, febrile illness associated with a slapped cheek appearance on the face and a lacy or reticular rash on the trunk and limbs
  • Severe anemia is the major complication due to the virus's predilection for red-cell precursors in the bone marrow
    • May cause aplastic crisis or persistent chronic anemia in immunocompromised patients
  • Migratory polyarthropathy may occur in up to 50% of adults – particularly females
    • Generally resolves within a few weeks
    • May persist for years (rare)
  • Pregnant females – abortion or stillbirth due to hydrops fetalis
    • Risk of transplacental infection – ~30%
    • Risk of fetal loss, predominantly in the early 2nd trimester – ~9%
    • Represents 10-20% of all cases of nonimmune hydrops
    • Congenital infections (primarily diagnosed by ultrasound)
      • Fetal risk greatest in 1st trimester; decreased in 2nd and 3rd trimesters
  • Associated with the onset of autoimmune disorders
  • Transient aplastic crisis may result in patients with increased erythropoiesis (hemoglobin disorders, hemoglobinopathies)
  • Chronic bone marrow failure and pure red-cell aplasia (PRCA) – may become persistent in patients unable to mount efficient immune response
    • PRCA or chronic anemia may result

Treatment

  • Treatment is symptomatic
  • Prophylactic immunoglobulin can be used in pregnant and immunocompromised patients
  • Weekly monitoring in utero for hemolysis required in parvo-exposed pregnant women

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Parvovirus B19 Antibodies, IgG and IgM 0065120
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Confirm infectious agent as parvovirus

Provide differential diagnosis for clinically significant chronic anemia in immunocompromised patients

Provide differential diagnosis for abortion or stillbirth due to hydrops fetalis

May be negative in immunocompromised patients and patients in transient aplastic crisis (TAC)

Sensitivity 70-80%

 
Parvovirus B19 Antibodies Seroconversion, IgG and IgM 0065109
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Diagnose presence of parvovirus infection in pregnant and/or at-risk populations

Presence of IgG with absent IgM indicates lifelong immunity

May be negative in immunocompromised patients and patients in TAC

Sensitivity ~70-80%

 
Parvovirus B19, by PCR, Bone Marrow 0060028
Method: Qualitative Polymerase Chain Reaction

Rule out parvovirus as causative agent in patients with aplastic anemia

Tissues may remain positive for life with low copy numbers

 
Parvovirus B19 by PCR 0060043
Method: Qualitative Polymerase Chain Reaction

Diagnose human parvovirus infection in patient with suppressed or delayed immune response

Low copy numbers may be detected for months after clinical resolution

 
Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Parvovirus B 19 Antibody, IgM 0065122
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Indicates acute exposure, especially in absence of IgG; IgM can remain positive for several months

Parvovirus B19 Antibody, IgG 0065121
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Presence of IgG in the absence of IgM indicates lifelong immunity