Erythema infectiosum is caused by acute infection with human parvovirus B19. In children, it causes mild constitutional symptoms and a blotchy or maculopapular rash beginning on the cheeks and spreading primarily to exposed extremities. In a fetus, it may be fatal. Diagnosis is clinical, and treatment is generally not needed.
Erythema infectiosum, often referred to as fifth disease, is caused by human parvovirus B19. The name "fifth disease" is used because it is considered the fifth viral infection that commonly causes rash in children (the first four are measles, rubella, chicken pox, and roseola). It is also sometimes called slapped-cheek disease.
It occurs mostly during the spring, commonly causing localized outbreaks every few years among children (particularly children aged 5 to 7 years).
Spread seems to be by respiratory droplets and by percutaneous exposure to blood or blood products, with high rates of secondary infection among household contacts; infection can be asymptomatic.
Infection may also occur in adults and may cause various clinical syndromes, including papular-purpuric gloves-and-socks syndrome, arthropathy, transient aplastic crisis, and pregnancy loss or hydrops fetalis. Based on seroprevalence surveys, 50 to 80% of adults have evidence of prior parvovirus B19 infection, which likely confers protective immunity for immunocompetent people.
Pathophysiology of Erythema Infectiosum
Parvovirus B19 is a single-stranded DNA virus that causes transient suppression of erythropoiesis that is mild and asymptomatic except in children with underlying hemoglobinopathies (eg, sickle cell disease) or other red blood cell (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). See table Clinical Manifestations of Parvovirus B19 Infection.
Parvovirus B19 infection in pregnancy
Erythema infectiosum can be transmitted transplacentally, sometimes resulting in miscarriage, 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 approximately 2 to 6% after maternal infection, with risk greatest during the first half of pregnancy (1).
Pathophysiology reference
1. Enders M, Weidner A, Zoellner I, et al: Fetal morbidity and mortality after acute human parvovirus B19 infection in pregnancy: Prospective evaluation of 1018 cases. Prenat Diagn 24(7):513–518, 2004. doi: 10.1002/pd.940
Symptoms and Signs of Erythema Infectiosum
The incubation period of parvovirus B19 infection is 4 to 14 days. Typical initial manifestations of erythema infectiosum 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 prominently on the arms, legs (often extensor surfaces), 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 typically last 5 to 10 days. However, the rash may recur for several weeks, exacerbated by sunlight, exercise, heat, fever, or emotional stress.
John Kaprielian/SCIENCE PHOTO LIBRARY
Image courtesy of Karen McKoy, MD.
Image courtesy of Karen McKoy, MD.
John Kaprielian/SCIENCE PHOTO LIBRARY
Image courtesy of Karen McKoy, MD.
Image courtesy of Karen McKoy, MD.
Other manifestations of parvovirus B19 infection
A few patients (more commonly children) develop papular-purpuric gloves-and-socks syndrome (PPGSS), which causes papular, purpuric, or petechial lesions limited to the hands and feet and is often accompanied by fever and oral and/or genital lesions.
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Some adults with parvovirus B19 infection develop mild joint pain and swelling (nonerosive arthritis) that may persist or recur for weeks to months.
Diagnosis of Erythema Infectiosum
Physical examination with characteristic rash
For children with risk factors for complications, viral testing and complete blood count
For pregnant patients, antibody measurement and ultrasonography
The rash's appearance and pattern of spread are the only diagnostic features; however, some enteroviruses may cause similar rashes. Distinguishing between these viral etiologies is seldom needed for the clinical care of otherwise healthy children. Rubella can be ruled out by serologic testing; an exposure history is also helpful. Other childhood exanthems have distinct diagnostic features.
Serologic testing is not required in otherwise healthy children; however, children with a known hemoglobinopathy or immunocompromised state should have viral and/or antibody testing as well as a complete blood count (CBC) and reticulocyte count to detect hematopoietic suppression.
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 polymerase chain reaction (PCR) techniques, which are generally used for patients with transient or chronic aplasia, patients who are immunocompromised, and fetuses or neonates with hydrops fetalis or congenital infection.
In pregnant patients, antibodies are measured; IgG suggests immunity due to prior infection (which is usually reassuring) and IgM indicates current or recent infection (which raises concern for potential fetal morbidity). Initial assessment of fetal status is with ultrasonography.
Treatment of Erythema Infectiosum
Supportive care
Only symptomatic treatment of erythema infectiosum is needed.
IV immune globulin has been used to curtail viremia and increase erythropoiesis in patients who are immunocompromised and have pure RBC aplasia.
Key Points
Children develop low-grade fever and slight malaise followed several days later by an indurated, confluent erythema on the cheeks (“slapped-cheek” appearance) and a symmetric rash that is most prominent on the arms, legs, and trunk.
There is mild, transient suppression of erythropoiesis that is asymptomatic except sometimes in children with hemoglobinopathies (eg, sickle cell disease) or other red blood cell disorders (eg, hereditary spherocytosis), or immunosuppression.
Risk of fetal death is 2 to 6% after maternal infection, with risk greatest during the first half of pregnancy.
Testing is done mainly in children with transient aplastic crisis or adults with arthropathy.
Treatment is symptomatic, but patients who are immunocompromised may benefit from IV immune globulin.
