(Fifth Disease; Parvovirus B19 Infection)
Most viruses that infect humans can affect both adults and children and are discussed elsewhere in THE MANUAL. Viruses with specific effects on neonates are discussed in Infections in Neonates. This chapter covers viral infections that are typically acquired during childhood (although many may also affect adults).
Erythema infectiosum, often referred to as fifth disease, is caused by human parvovirus B19. 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 occur without symptoms or signs.
Parvovirus B19 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).
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 2 to 6% after maternal infection, with risk greatest during the first half of pregnancy.
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 (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 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. 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.
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, children with a known hemoglobinopathy or immunocompromised state should have complete blood count (CBC) and reticulocyte count to detect hematopoietic suppression as well as viral testing.
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 aplastic crisis, immunocompromised patients with pure RBC aplasia, and infants with hydrops fetalis or congenital infection.
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.
Testing is done mainly in children with transient aplastic crisis or adults with arthropathy.
Treatment is symptomatic, but immunocompromised children may benefit from IV immune globulin.