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Erythema Infectiosum (Fifth Disease)
Eleanor J. Rutherford, MD
Most of the common viral exanthems are part of self-limited illnesses. Viral exanthems, bacterial and rickettsial infections can also be a cause of febrile exanthems, and failure to correctly distinguish viral from bacterial exanthems can have fatal consequences. Fulminant illnesses with an early exanthematous phase such as meningococcemia, Kawasaki syndrome, or the bacterial toxic shock syndromes require prompt intervention. Viral illnesses such as rubella and erythema infectiosum can lead to serious complications for developing fetuses when pregnant women are exposed and become infected.
Although the clinical morphology of certain exanthems can be highly specific (ie, "slapped-cheek appearance" and reticulated erythema in erythema infectiosum), in most cases the skin eruption alone will not permit accurate diagnosis. Cutaneous physical findings must be interpreted in concert with the past history of infectious diseases and immunizations, the type of prodromal period, the physical examination of the patient beyond the mucocutaneous assessment, and current infectious disease epidemiology in the community.
In a study of 100 children with acute febrile illness and rash, infectious agents were identified in 65, with viruses accounting for 72%. Bacterial pathogens were detected in 20%, most commonly group A streptococci. This supports the common clinical impression that most childhood exanthems are viral in origin, but points up the surprising frequency of bacterial exanthematous illness. The broad scope of childhood exanthematous illness has been thoroughly reviewed in several publications. In this article, newer developments and timely issues related to selected childhood exanthems are reviewed.
Erythema infectiosum is a common childhood eruption with several distinctive clinical features. The most characteristic feature is the rapid appearance of facial erythema, which is typically bright red and macular and favors the malar surface. The so-called slapped cheek appearance of erythema infectiosum is accentuated by the sparing of the orbit, nasal bridge, and skin around the mouth.
A rash involving other skin surfaces may evolve simultaneously with or several days after the facial eruption. Macular or morbilliform erythema, with or without pruritus, may involve any anatomic location, including the palms and soles. Most commonly, the eruption is limited to the extensor surface of the extremities and the buttocks. Over a period of several days, the rash may take on a lacy or reticular pattern, which, when present, is virtually pathognomonic of fifth disease. In rare cases, the reticular eruption may occur without the presence of facial erythema.
The tendency for the rash to flare in response to certain physical stimuli is common in fifth disease and may aid significantly in the diagnosis of this disorder. Exposure to heat or sunlight may bring out the rash, and the reappearance of skin lesions after a warm bath is particularly characteristic.
The exanthem of fifth disease is occasionally preceded by a mild prodrome of low-grade fever, malaise, sore throat, and coryza. For most children it is a benign illness that resolves spontaneously over a period of 1 to 2 weeks. In some patients, however, the rash may recur periodically for a period of a month or longer before it disappears completely.
Fifth disease derives its unusual name from the assignment of numbers to the childhood exanthems. Cheinisse of Paris assigned the number 5 to erythema infectiosum in 1905. The cause of fifth disease is now known to be human parvovirus B19. Parvovirus B19 infection, which is often asymptomatic, is most common among school-aged children and is probably spread by respiratory secretions. The incubation period is usually 4 to 14 days, but may occasionally be as long as 3 weeks. Parvovirus B19 infection often occurs in epidemics that start in the late winter and spring and last 2 to 6 months. Fifty percent of adults have serologic evidence of prior infection.
Parvovirus B19 infection in adults may also cause a reticulated erythematous eruption associated with a symmetrical polyarthropathy involving the hands, feet, and knees. Parvovirus B19 is also implicated in the etiology of aplastic crises in patients with underlying hemolytic anemias. Rarely, the infection has been reported to cause hepatitis. In addition, infection during pregnancy may result in fetal hydrops and stillbirth. Children with erythema infectiosum are no longer infectious, do not represent a risk to pregnant women, and may attend school or daycare.
Papular-Purpuric Gloves and Socks Syndrome
Acute parvovirus B19 infection has recently been associated with a unique exanthem that localizes to the hands and feet. In 1990 Harms and colleagues reported an acute, self-limited dermatosis occurring in five young adults, characterized by the sudden onset of confluent erythema and papules that evolved to become petechial and purpuric. The name papular purpuric gloves and socks syndrome (PPGSS) was coined because the eruption was sharply demurcared at the ankles and wrists. These previously healthy patients developed fever and intraoral aphthous ulcers along with the exanthem. Attempts to identify a viral etiology were unsuccessful.
In the early 1990s several authors described similar cases of PPGSS associated with documented acute parvovirus B19 infection including a case in a 9-year-old child. An additional report of a purpuric buttock eruption and "Koplik spots" was reported in association with acute parvovirus B19 infection.
Five additional cases of PPGSS were reported in 1994. This report suggested that although many cases of PPGSS are caused by parvovirus B19, other viruses, including coxsuckle virus B6, could also cause the same reaction pattern.
References
1. Anderson LJ, Lewis E, Kidd IM, et al: An outbreak of erythema infectiosum associated with human parvovirus infection. J Hyg (Camb) 93:85, 1984
2. Anderson LJ: Role of parvovirus B19 in human disease. Pediatr Infect Dis J 6:711, 1987
3. Committee on Infectious Diseases, American Academy of Pediatrics. Parvovirus, erythema infectiosum, and pregnancy. Pediatrics 85:130, 1990