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Erythema infectiosum, acute infection with parvovirus B19, causes mild constitutional symptoms and a blotchy or maculopapular rash beginning on the cheeks and spreading primarily to exposed extremities. Diagnosis is clinical, and treatment is generally not needed.
The disease is caused by human parvovirus B19. It occurs mostly during the spring, commonly causing localized outbreaks every few years among children (particularly children 5 to 7 yr). Spread seems to be by respiratory droplets, with high rates of secondary infection among household contacts; infection can occur without symptoms or signs.
Pathophysiology
Parvovirus B19 causes transient suppression of erythropoiesis that is mild and asymptomatic except in children with underlying hemoglobinopathies (eg, sickle cell disease) or other RBC disorders (eg, hereditary spherocytosis), who may develop transient aplastic crisis. Also, immunocompromised children can develop protracted viremia (lasting weeks to months), leading to severe anemia (pure RBC aplasia).
Erythema infectiosum can be transmitted transplacentally, sometimes resulting in stillbirth or severe fetal anemia with widespread edema (hydrops fetalis). However, about half of pregnant women are immune because of previous infection. The risk of fetal death is 5 to 9% after maternal infection, with risk greatest during the 2nd trimester.
Symptoms and Signs
The incubation period is 4 to 14 days. Typical initial manifestations are nonspecific flu-like symptoms (eg, low-grade fever, slight malaise). Several days later, an indurated, confluent erythema appears over the cheeks (“slapped-cheek” appearance) and a symmetric rash appears that is most prominent on the arms, legs, and trunk, usually sparing the palms and soles. The rash is maculopapular, tending toward confluence; it forms reticular or lacy patterns of slightly raised, blotchy areas with central clearing, usually most prominent on exposed areas. The rash, and the entire illness, generally lasts 5 to 10 days. However, the rash may recur for several weeks, exacerbated by sunlight, exercise, heat, fever, or emotional stress. Mild joint pain and swelling (nonerosive arthritis) that may persist or recur for weeks to months sometimes occurs in adults.
Diagnosis
The appearance and pattern of spread of the rash are the only diagnostic features; however, some enteroviruses may cause similar rashes. Rubella can be ruled out by serologic testing; an exposure history is also helpful. Serologic testing is not required in otherwise healthy children; however, in children with transient aplastic crisis or adults with arthropathy, the presence of IgM-specific antibody to parvovirus B19 in the late acute or early convalescent phase strongly supports the diagnosis. Parvovirus B19 viremia also can be detected by quantitative PCR techniques, which are generally used for patients with transient aplastic crisis, immunocompromised patients with pure RBC aplasia, and infants with hydrops fetalis or congenital infection.
Treatment
Only symptomatic treatment is needed. IV immune globulin has been used to curtail viremia and increase erythropoiesis in immunocompromised children with pure RBC aplasia.
Last full review/revision March 2010 by Geoffrey A. Weinberg, MD
Content last modified February 2012
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