Picture of the Month

Figure 1. The lips are swollen and 2 shallow ulcers are visible on the undersurface of the tongue.

Figure 2. A discrete petechial rash is present on the feet.

Figure 3. A discrete petechial rash is present on the hand and the fingers are swollen.

Parvovirus B19, discovered in 1974, is a small, nonenveloped, single-stranded DNA virus, belonging to the family Parvoviridae.^1,2 Infection with Parvovirus B19 is common. The prevalence of IgG antibodies to the virus ranges from 2% to 15% in children from 1 to 5 years of age and from 30% to 60% in adults.^3,4 Clinical infection with this virus is most common in school-aged children. The mode of spread is believed to be by respiratory droplets. Secondary spread among susceptible household members occurs in about 50% of contacts.³

In the immunologically normal host, Parvovirus B19 infection may be asymptomatic, may result in erythema infectiosum (fifth disease), or may induce arthritis.^5,6 Erythema infectiosum, characterized by the "slapped cheek" appearance and lacey erythema of the proximal extremities, is the most common clinical manifestation of Parvovirus B19 infection and occurs most frequently in school-aged children. Once the rash appears, the children are no longer capable of transmitting the disease.

Petechial rashes, with or without thrombocytopenia and vesiculobullous lesions, have also been associated with Parvovirus B19 infections.^7,8 More recently, a distinctive exanthem known as the papular-purpuric "gloves and socks" or the petechial gloves and socks syndrome has been described in older children and adults, many of whom have demonstrated evidence of Parvovirus B19 infection.^9-11 The clinical picture of this illness is characterized by pruritic edema and erythema of the hands and feet in a gloves and socks distribution, oral lesions, and fever, followed by the rapid development of petechiae on the hands and feet.

Parvovirus B19 may cause an aplastic crisis in patients with chronic hemolytic anemias. Although megakaryocytes and myeloid cells are not infected, neutropenia, thrombocytopenia, or both are commonly found in these patients.^12,13 In patients with immunodeficiency, congenital or acquired, Parvovirus B19 infection may become chronic, resulting in persistent viremia and bone marrow failure. Most of these immunodeficient patients do not experience the rash, fever, or polyarthropathy frequently associated with this infection.¹⁴

Parvovirus B19 infection has also been implicated as a possible cause of idiopathic thrombocytopenic purpura. In a series of 35 previously healthy children with classic idiopathic thrombocytopenic purpura, almost half had evidence of Parvovirus B19 DNA in peripheral blood or bone marrow, while none of 14 control patients had polymerase chain reaction or anti–B19 IgM antibodies.¹⁵Parvovirus B19 infection also accounts for as much as one fourth of the cases of nonimmune fetal hydrops by causing red blood cell aplasia.¹⁶

In addition, Parvovirus B19 has been demonstrated to be a cause of arthritis, chronic encephalitis, and aseptic meningitis among otherwise normal children.⁶

In the healthy host, detection of IgM antibodies to Parvovirus B19 denotes a recent infection. Both IgM and IgG antibodies are present soon after the onset of illness and reach peak titers in the first 30 days. IgG antibodies persist for years, but IgM antibody levels begin to decline 30 to 60 days after the onset of the illness. Hybridization techniques or polymerase chain reaction may also be useful in detecting Parvovirus B19 infection. These techniques have been used to detect viral DNA in clinical samples of serum, urine, respiratory secretions, and body tissues.

Antiviral therapy for this infection is unavailable. For most patients, supportive care only is indicated. Intravenous immunoglobulin therapy may be effective in treating Parvovirus B19 infection in immunodeficient patients.¹⁴

Accepted for publication September 5, 1997.

Reprints: Basim Asmar, MD, Children's Hospital of Michigan, 3901 Beaubien Blvd, Detroit, MI 48201-2196.