Parvovirus B19

Case

A seven year old girl comes to your office because of a rash on her cheeks and upper and lower extremities. There is no itching and the child is not ill. The mother of the child is 5 months pregnant. How would you advise the mother?

Parvovirus B19 is a small DNA virus that infects only humans. It was discovered in 1975. The primary target of the virus is the red cell precursors in the bone marrow. The virus is spread by the respiratory route and the subsequent rash that develops is secondary to an immune response. In human volunteers, 7-11 days after inoculation with the virus, they developed a viremia and the presence of virus in the nasopharynx with low grade fever, URI symptoms and malaise. There was a decreased production of reticulocytes and a subsequent slight fall in the hemoglobin level. Three weeks after inoculation patients developed a rash and arthropathy and at the time the rash developed, the patients were not viremic.

Clinical Manifestations

  1. Fifths Disease-Erythema Infectiosum
    1. prevalent in the late winter and spring. 
    2. Prior to rash appearing may have had a low grade fever and headache.  The prodrome is mild.
    3. The rash appears as "slapped cheeks" and a lacy maculopapular rash on the extensor surfaces. trunk, nd buttocks.
    4. Usually not pruritic and spares the palms and soles. 
    5. Patients are not contagious after the rash appears and they may attend school. 
    6. The rash may disappear and then return over periods of weeks, especially with sunlight exposure, during exercise and heat exposure
  2. RBC aplasia 
    1. The virus directly infects the RBC precursors in the marrow and causes decreased production. Usually spares the neutrophile and platelet lines. 
    2. Clinically relevant in situations where there is a shortened red cell life span and increased turnover. Any hemolytic disease is susceptible and aplasia may necessitate transfusions. During this period the patients must be isolated in the hospital because they are contagious.
    3. May also cause transient aplasia in Iron deficiency states.
    4. In immunocompromised hosts, Parvovirus may chronically infect the marrow.
  3. Fetal Hydrops
    1. infected fetuses will have severe anemia, high output failure, and extramedullary hematopoiesis. The highest risk is during the first 20 weeks of gestation. There may be a direct affect of the virus on the myocardium. 
    2. The risk of fetal infection is 1.5- 2.5% after exposure of pregnant woman to the disease. (50% susceptibility) x(30-50% rate of infection) x(10% infection rate of fetus)
    3. 15% fetal loss during the firt 20 weeks.
  4. Arthropathy
    1. Unusual in young children 
    2. usually self limited
    Diagnosis
    1. Increased IgM levels during the acute phase. Few labs do the test. 
    2. Presence of increased IgG titers usually not helpful although seroconversion is indicative of infection.
    3. Clinical diagnosis
    Management
    1. Once the child has the rash, they may attend school
    2. Patients with hemolytic anemia may have transient aplasia necessitating transfusion of RBCs
    3. Exposed pregnant woman
      1. The mother should inform her obstetrician that she was exposed to Parvovirus B19. 
      2. IgG titers should be drawn and if the mother is seronegative, she should be advised of the low risk of fetal wastage and the pregnancy should be monitored closely with alpha-feto-protein and ultrasounds if she seroconverts.
    4. Symptomatic treatment for most children and adults with acetaminophen and NSAID for fever, headache, myalgia, and joint symptoms. 
    5. Use of IVIG for immunocompromised exposed patients and pregnant women has not been proven to be effective.
    6. Vaccine?
        7.  
References
  1. Adams, Denise and Ware, Russell. Parvovirus B19: How much should you worry? Contemporary Pediatrics April 1996.
  2. Resnick SD. New Aspects of Exanthematous Diseases of Childhood. Dermatologic Clinics. 1997; 15(2):257-266.
  3. Walther RR. What is New in Clinical Research of Viral Deseases of the Skin. Dermatologic Clinics. 1997; 15(1):189-196.
  4. Katta R. ParvoVirus B19: A Review.  Dermatologic Clinics Vol20 No. 2 April 2002 (MD Consult)
  5. Sabella C. and Goldfarb J. Parvo B19 Infections. American Family Physician. Vol 60 No. 5 Oct. 1, 1999
  6. Young N.S. Brown K.E. Mechanisms of Disease: Parvovirus B19.  NEJM Vol. 350 No. 6. pg 596. Feb 5, 2004
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