Roseola is a common childhood disease. The cause is primary infection with human herpesvirus 6 (HHV-6). The classic presentation of roseola infantum is a 9- to 12-month-old infant who acutely develops a high fever and often a febrile seizure. After 3 days, a rapid defervescence occurs, and a morbilliform rash appears (see the image below).
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Roseola infantum. Image courtesy of Wikimedia Commons.
Like other herpes viruses, HHV-6 then remains latent in most patients who are immunocompetent. Although clinical disease is uncommon in patients who are immunocompetent, HHV-6 is a major cause of morbidity and mortality in patients who are immunosuppressed, particularly in patients with AIDS and in those who are transplant recipients (eg, liver transplantation[1, 2] ).
In the primary infection, replication of the virus occurs in the leukocytes and the salivary glands. HHV-6 is present in saliva. A study monitoring HHV-6 and HHV-7 DNA in saliva samples during the acute and convalescent phases demonstrated a significantly higher rate of detection in children aged 3-9 years versus adults, suggesting that children in the convalescent phase of roseola infantum are the more probable source of infection.[3] Early invasion of the CNS is believed to occur, thus accounting for seizures and other CNS complications. Evidence suggests that high serum levels of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinases 1 in infants infected with HHV-6 may lead to blood-brain barrier dysfunction, which may result in febrile seizures.[4] Study of cerebrospinal fluid levels of interleukin 1β and basic fibroblast growth factor may indicate a role in contributing to HHV-6B growth and the onset of encephalitis.[5] Although rare in the primary disease of infancy, generalized organ involvement has been reported with gastrointestinal, hematopathic syndromes; hepatitis; and hepatosplenomegaly.
Following the acute primary infection, HHV-6 remains latent in lymphocytes and monocytes and has been found in low levels in many tissues. Peripheral blood mononuclear cell cultures develop enlarged balloonlike cells. Cells supporting virus growth are CD4+ T lymphocytes. HHV-6 down-regulates the host immune response through several mechanisms, including molecular mimicry by production of functional chemokine and chemokine receptors.
The two variants of HHV-6 are A and B. The genomes of HHV-6A/B have been sequenced. HHV-6B, the main cause of roseola, consists of 97 unique genes. CD46 is the cell receptor for HHV-6, which imparts the virus' broad tissue tropism.
A possible association of HHV-6 and multiple sclerosis has been suggested but is still inconclusive. HHV-6 has been isolated in Kaposi sarcoma (caused by human herpesvirus 8), in which it may contribute to tumor progression. HHV-6 may facilitate oncogenic potential in lymphoma and has been associated with chronic fatigue syndrome.
The causative agent of roseola infantum was discovered in 1986. The Roseolovirus genus of the beta herpes virus hominis subfamily contains human herpesvirus (HHV)–6 and HHV-7. HHV-6 has 2 variants: HHV-6A and HHV-6B. Their major differences are cellular tropism. Debate has existed whether they represent 2 species.
HHV-6A infection is rarely associated with roseola infantum. HHV-6A is associated with infection in adults who are immunocompromised. HHV-6A infection occurs later in life, and details are lacking.
HHV-6B is the cause of roseola in infants. Because seropositivity is nearly 100% in older children, most primary infections with HHV-6B are asymptomatic. HHV-7 has been identified in a few cases of roseola infantum.
Recurrences of roseola infantum are not common. A well-documented case of a 13-month-old child who had a second episode of roseola exists. In the acute phase of the second episode, HHV-7 was identified and excreted in the saliva. This was followed by excretion of HHV-6.
Serologic tests indicate that human herpesvirus 6 (HHV-6) infection is nearly universal. In emergency clinics, HHV-6 has been reported to be responsible for 10-45% of cases of febrile illness in infants. A 2005 population-based study revealed primary HHV-6 infection cumulative percentages of 40% by age 12 months and 77% by age 24 months.[6] The peak age of acquisition of primary HHV-6 infection is 9-21 months.
International
International studies show some variation in worldwide seroprevalence. A strong association of HHV-6A in Zambian children with febrile illness suggests an endemic hot spot.
Race
With rare geographic exceptions, no racial differences seem to occur in HHV-6 infection.
Sex
Zerr et al reported HHV-6 acquisition is associated with female sex and having older siblings.[6]
Age
Antibody titers are high in newborns because of maternal antibody. Transplacental infection occurs in about 1% of cases. Titers decrease from 3-9 months of age and then begin to rise because of primary infections. Titers remain high for HHV-6B until after age 60 years. Infection with HHV-6A appears later in life. In roseola infantum, age ranges from 2 weeks to 3 years. In one study, almost one fourth of the patients were younger than 6 months. In a Brazilian study, 75% of HHV-6 infections occurred in children aged 6-17 months.[7]
Practically all patients who are immunocompetent survive roseola infantum without sequelae. In patients who are immunosuppressed, multisystem complications are not unusual. Infection may be chronic, leading to viral progression and death.
Primary infection with HHV-6 may be asymptomatic, or it may cause the exanthem subitum/roseola syndrome.[8] Within that complex, otitis, gastroenteritis, respiratory distress, and seizures may occur. Primary infection in infants is rarely complicated by serious disease and is very rarely fatal. Case reports of many organ systems being involved indicate a potential morbidity, although this is rarely observed.
The second stage of HHV-6 infection occurs in healthy children and adults. The virus replicates in the salivary glands and is latent in peripheral blood mononuclear cells. A form of latent infection is found in the integration of the virus in host chromosomes. In adults who are immunocompetent, infection or reactivation of HHV-6 is rare. These few patients have been reported to have lymphadenopathy, hepatitis, and a mononucleosislike syndrome.
In patients who are immunocompromised, a more serious disease is seen. Transplant recipients (eg, marrow, kidney, liver) may have marrow suppression, pneumonitis, encephalitis, hepatitis, fever, and an eruption. Organ rejection and death may occur.[9] Studies of these patients are complicated by frequent concomitant reactivation of human herpesvirus 7 (HHV-7) and cytomegalovirus. HHV-6 was implicated as the cause of 30% of cases of pneumonitis in patients who underwent bone marrow transplantation. Patients with AIDS comprise the second at-risk group; however, antiretroviral therapy has reduced morbidity. HHV-6 infection in patients with AIDS results in viremia, lymphadenopathy, disseminated organ involvement, active CNS infection, retinitis, and death. HHV-6A is more common in patients with AIDS than in other patients.
In the case of an otherwise healthy infant with roseola infantum, educating the parents is important to alleviate anxiety about the hyperpyrexia and possible associated seizure.
In patients who are immunocompromised, the complexity of overlapping signs and symptoms with other viral syndromes and parasitic and fungal infections must be explained.
For patient education resources, see the Children's Health Center, as well as Skin Rashes in Children.
The classic roseola infantum patient is a 9- to 12-month-old infant in previously good health and who has an abrupt onset of high fever (40°C), which lasts for 3 days with nonspecific complaints. A febrile seizure occurs in 15% of patients. Rapid defervescence is striking with the onset of a mild, pink, morbilliform exanthem.
In roseola infantum patients who are immunocompromised, the onset of symptoms is usually abrupt, with fever, malaise, and CNS and other organ system involvement.
Despite the high fever, few clinical findings are observed early in the course of roseola infantum. The lack of upper respiratory tract infection is notable, and meningeal signs and encephalopathy are not present. Gastrointestinal symptoms, signs of electrolyte imbalance, or evidence of dehydration are rarely present.
A febrile seizure, with no residual findings, may have occurred.
After an abrupt loss of fever, the characteristic rash appears. The eruption is generalized and subtle. It is composed of either discrete, small, pale pink papules or a blanchable, maculopapular exanthem that is 1-5 mm in diameter. This rash may last 2 days.
The characteristic enanthem (Nagayama spots) consists of erythematous papules on the mucosa of the soft palate and the base of the uvula. The enanthem may be present on the fourth day in two thirds of patients with roseola.
See the images below.
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Roseola infantum. Image courtesy of Wikimedia Commons.
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Roseola infantum. Image courtesy of Wikimedia Commons.
In roseola infantum, complications are rare. Given that seroconversion is practically universal, finding any of the complications that have been reported in the gastrointestinal, central nervous, pulmonary, and hematopoietic systems is rare.
Children who have seizures with roseola are not expected to have further febrile or nonfebrile seizures.
In response to the early acute febrile presentation, laboratory studies may include a CBC count, urinalysis, blood cultures, and cerebrospinal fluid examination.
If the patient presents with a febrile seizure, a seizure workup may be indicated.
Roseola infantum diagnosis may be confirmed by virus isolation, seroconversion (immunoglobulin M), or detection of viral DNA sequences in peripheral blood mononuclear cells.
Specific antibodies to differentiate human herpesvirus (HHV)–6A- and HHV-6B can be determined using a serological assay based on immunoblot analysis using recombinant HHV-6A p100 and HHV-6B 101K.[12]
At present, no medical antiviral therapy is available for human herpesvirus 6 (HHV-6) infection that causes roseola. Thus, treatment of roseola infantum is supportive.[13] However, in 2002, Rapaport et al reported that antiviral prophylaxis with ganciclovir may prevent HHV-6 reactivation in high-risk bone marrow transplant patients.[14] Further double-blinded randomized studies are needed.
Short- or long-term antiseizure medications are not recommended for infants who have had a febrile seizure secondary to roseola.
Inpatient care for roseola infantum consists of support with antipyretics and treatment of gastroenterologic, respiratory, hematologic, or CNS complications.
Because seroconversion in the United States is nearly 100%, isolation is not indicated. The infection is spread through saliva in both the acute phase and the chronic phase.
No risk appears to be present to pregnant women exposed to roseola. Care must be taken to distinguish this from rubella. No reports of infection or complications following exposure exist. This is probably because of the nearly universal seroconversion and latent infection. No sequelae of intrauterine infection are known. Isolation is not indicated.
What is roseola infantum?What is the pathophysiology of roseola infantum?What causes roseola infantum?What is the prevalence of roseola infantum in the US?What is the international prevalence of roseola infantum?What are the demographics of roseola infantum?What is the general prognosis of roseola infantum?What is the prognosis of roseola infantum in patients who are immunocompromised?What information should be provided to parents/caregivers of patients with roseola infantum?What is the patient history in roseola infantum?What are the clinical findings in roseola infantum?What are the complications of roseola infantum?What are the diagnostic considerations in roseola infantum?What are the differential diagnoses for Roseola Infantum?Which lab studies are indicated in the workup of roseola infantum?What are the histologic findings in roseola infantum?What is the medical care of roseola infantum?Which specialist consultations are indicated in the treatment of roseola infantum?How is roseola infantum prevented?What is the cure for roseola infantum?
Christopher R Gorman, MD, Dermatologist, McGuire VA Medical Center
Disclosure: Nothing to disclose.
Specialty Editors
Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Disclosure: Nothing to disclose.
Paul Krusinski, MD, Director of Dermatology, Fletcher Allen Health Care; Professor, Department of Internal Medicine, University of Vermont College of Medicine
Disclosure: Nothing to disclose.
Chief Editor
William D James, MD, Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine
Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD.
Additional Contributors
Franklin Flowers, MD, Department of Dermatology, Professor Emeritus Affiliate Associate Professor of Pathology, University of Florida College of Medicine
Disclosure: Nothing to disclose.
Acknowledgements
Acknowledgments
Medscape Drugs & Diseases wishes to recognize Stephen W White, MD† for his original contributions to this article.
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