Children infected by human herpesvirus 6B with febrile seizures are more likely to develop febrile status epilepticus: A case-control study in a referral hospital in Zambia.

BACKGROUND: Human herpesvirus 6B (HHV-6B) is the causative agent of Roseola infantum, and has also been suggested to play a role in the pathogenesis of febrile seizures in young children, a percentage of whom go on to develop febrile status epilepticus (FSE), but the existing data is conflicting and inconclusive. HHV-6A is a distinct species, rarely detected in most parts of the world, but prior studies suggest a higher prevalence in febrile African children. We describe a case-control study comparing the frequency of HHV-6A and/or HHV-6B infections in children with febrile seizures (including FSE) and a control group of febrile children without seizures. METHODS: We recruited children aged 6 to 60 months admitted with a febrile illness with (cases) or without (controls) seizures presenting within 48 hours of commencement of fever. Three milliliters of whole blood was centrifuged and plasma stored at -80°C for pooled screening for HHV-6B and HHV-6A by Taqman real-time polymerase chain reaction. RESULTS: 102 cases and 95 controls were recruited. The prevalence of HHV-6B DNA detection did not differ significantly between cases (5.8% (6/102)) and controls (10.5% (10/95)) but HHV-6B infection was associated with FSE (OR, 15; 95% CI, [1.99-120]; P= 0.009). HHV-6A was not detected. CONCLUSION: Prevalence of HHV-6B was similar among cases and controls. Within the FS group, HHV-6B infection was associated with FSE, suggesting HHV-6B infections could play a role in the pathogenesis of FSE.

Case report of drug rash with eosinophilia and systemic symptoms demonstrating human herpesvirus-6 reactivation.

Drug rash with eosinophilia and systemic symptoms (DRESS) is a severe drug-induced hypersensitivity syndrome that presents with diffuse cutaneous eruptions, fever, and multiorgan involvement. Here we present a pediatric case of DRESS complicated by human herpesvirus (HHV)-6 reactivation. After 1 week of sulfasalazine, our patient developed a diffuse morbilliform eruption. Sulfasalazine was discontinued. The patient presented to the emergency department soon thereafter with worsening eruption, fever, rigors, facial edema, and lymphadenopathy. Methylprednisolone was initiated. Peripheral smear did not demonstrate eosinophilia but showed toxic granulation with atypical lymphocytes. Transaminase levels and white blood cell count quickly became elevated, with increased eosinophils, suggesting DRESS. During the methylprednisolone taper, our patient experienced symptom exacerbation, acute hepatitis, and HHV-6 seroconversion, indicating HHV-6 reactivation as the cause. As demonstrated by our patient, a decelerated methylprednisone taper is important because of potential symptom flaring during taper. Additionally, in the care of individuals with DRESS, HHV-6 is often tested for upon admission and not repeated. Delay in the rise of titers necessitates repeat testing.

Exanthem subitum-associated encephalitis: nationwide survey in Japan.

We sought to clarify clinical features of exanthem subitum associated-encephalitis/encephalopathy, generally caused by primary human herpesvirus-6 infection in Japan. A two-part questionnaire was sent to hospitals between January 2003-December 2004. Of 3357 questionnaires, 2357 (70.2%) were returned, and 2293 (68.3%) were eligible for analysis. Eighty-six cases of exanthem subitum-associated encephalitis/encephalopathy were reported. Seventy-seven (89.5%) of 86 patients were diagnosed with human herpesvirus-6 infection by virologic examination. Although 41 (50.6%) of 81 patients had no sequelae, 38 (46.9%) had neurologic sequelae. Moreover, two fatal cases (2.5%) were reported. Pleocytosis was evident in only 4 (7.5%) of 53 patients, and cerebrospinal fluid protein levels were within normal range (23.4 +/- 14.6 mg/dL S.D.) in all patients. Human herpesvirus-6 DNA was detected in 21 (53.8%) of 39 patients. Abnormal computed tomography findings were a predictor of neurologic sequelae (P = 0.0097). As a consequence of this survey, we estimate that 61.9 cases of exanthem subitum-associated encephalitis occur every year. The disease prognosis was unexpectedly poor.

Papular-purpuric gloves and socks syndrome in children and adolescents.

We describe the case of a 12-year-old boy with gloves and socks syndrome caused by coinfection with HHV-6 and PVB19, and review the published cases from 5 to 18 years of age to profile the disease in this age group. The review of the literature yielded 25 cases of gloves and socks syndrome. Most patients were febrile and had acute PVB19 infection.

Molecular biology and clinical associations of Roseoloviruses human herpesvirus 6 and human herpesvirus 7.

Human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) are members of the Roseolovirus genus within the Betaherpesvirinae subfamily. HHV-6 and HHV-7 primary infection occurs in early childhood and causes short febrile diseases, sometimes associated with cutaneous rash (exanthem subitum). Both HHV-6 and HHV-7 are highly prevalent in the healthy population, establish latency in macrophages and T-lymphocytes, are frequently shed in saliva of healthy donors, and the pathogenic potential of reactivated virus ranges from asymptomatic infection to severe diseases in transplant recipients. These features have contributed to the notion that HHV-6 and HHV-7 are more or less "harmless" viruses. Consequently, the medical and scientific interest originally prompted by their discovery has been gradually waning. The aim of this review is to provide a short update of the current knowledge on these viruses, and to suggest that the medical importance of Roseoloviruses should not be understimated.

Serial changes on diffusion-weighted magnetic resonance imaging in encephalitis or encephalopathy.

It is recognized that diffusion-weighted magnetic resonance imaging is a sensitive method of detecting cerebral lesions in various neurologic disorders. This report presents two patients with acute encephalitis or encephalopathy who manifested similar serial changes on diffusion-weighted magnetic resonance imaging. Clinically, Patient 1, a 2-year-old male, was diagnosed as having hemiconvulsion-hemiplegia-epilepsy syndrome and Patient 2, a 9-month-old male, acute encephalitis associated with exanthema subitum. Despite the different etiology and the distribution of lesions, diffusion-weighted magnetic resonance imaging of these two patients revealed high-intensity lesions in the subcortical white matter in the acute phase, and then in the cortex, or basal ganglia, or both. In the convalescent phase, high-intensity lesions disappeared and brain atrophy developed. These serial changes were not recognized using other conventional methods. Although the exact mechanism for these serial changes remains unknown, these changes might reflect some pathogenic mechanism in acute encephalopathy or encephalitis.

Differential tropism of human herpesvirus 6 (HHV-6) variants and induction of latency by HHV-6A in oligodendrocytes.

Human herpesvirus 6 (HHV-6) is a ubiquitous beta -herpesvirus associated with a number of clinical disorders. Two closely but biologically distinct variants have been described. HHV-6 variant B causes the common childhood disease exhanthem subitum, and although the pathologic characteristics for HHV-6 variant A are less well defined, HHV-6A has been suggested to be more neurotropic. We studied the effect of both HHV-6 variants in an oligodendrocyte cell line (MO3.13). Infection of M03.13 was monitored by cytopathic effect (CPE), quantitative TaqMan PCR for viral DNA in cells and supernatant, reverse transcriptase-polymerase chain reaction (RT-PCR) to detect viral RNA, and indirect immunofluorescence (IFA) to detect viral protein expression. HHV-6A infection induced significantly more CPE than infection with HHV-6B. HHV-6B induced an abortive infection associated with a decrease of the initial viral DNA load over time, early RNA expression, and no expression of viral antigen. In contrast, infection with HHV-6A DNA persisted in cells for at least 62 days. During the acute phase of infection with HHV-6A, intracellular and extracellular viral load increased and cells expressed the viral protein IE-2 and gp116/54/64. No HHV-6A RNA or protein was expressed after 30 days post infection, suggesting that HHV-6A formed a latent infection. These studies provide in vitro support to the hypothesis that HHV-6 can actively infect oligodendrocytes. Our results suggest that HHV-6A and HHV-6B have different tropism in MO3.13 cells and that an initially active HHV-6A infection can develop latency. Differences between HHV-6A and -6B infection in different neural cell types may be associated with different neurological diseases.

Drug-induced hypersensitivity syndrome associated with human herpesvirus 6 and cytomegalovirus reactivation.

We describe a patient with drug-induced hypersensitivity syndrome (DIHS) associated with human herpesvirus 6 (HHV-6) and cytomegalovirus (CMV) infection induced by sulfasalazine. Two weeks after starting sulfasalazine to treat a rectal ulcer, the patient developed disseminated macular erythema accompanied by fever, liver injury, and lymphadenopathy. Seroconversion of antibodies to HHV-6 was observed. Systemic steroid treatment was not effective against the eruptions. Five months after the onset, he presented with an acute febrile disease. The detection of CMV antigen on peripheral blood leukocytes and positive staining for CMV on cutaneous endothelium indicated active CMV infection. Furthermore, he developed a bacteremia of methicillin resistant Staphylococcus aureus. An association the CMV reactivation with DIHS was suggested, although there remains the possibility that the systemic steroid treatment precipitated CMV reactivation. Recently, HHV-6 has been documented to have immunomodulating effects and to be associated with CMV reactivation. Therefore, we should pay attention to the possibility of CMV reactivation in patients with DIHS in whom the immunomodulating virus of HHV-6 has been reactivated.

Prevalence and cellular reservoir of latent human herpesvirus 6 in tonsillar lymphoid tissue.

There are few studies that examine prevalence, quantity, and cellular proclivity of latent human herpesvirus 6 (HHV-6) in healthy populations. We examined 69 tonsils with paired blood specimens from children without evidence of acute infection. By polymerase chain reaction (PCR), HHV-6 was detected at low levels in 100% of tonsils and 39% of blood samples (n = 27), suggesting that prevalence of latent HHV-6 infection is high in children and may be underestimated by PCR analysis of blood. Although HHV-6A and HHV-6B were detected, HHV-6B predominated, being found in 97% of samples (n = 67). Tonsil sections from 7 cases were examined by in situ hybridization using 2 HHV-6 probes and immunohistochemical analysis. Using both in situ hybridization and immunohistochemical analysis, all tissues revealed marked HHV-6-specific staining in the squamous epithelium of the tonsillar crypts and rare positive lymphocytes. We conclude that HHV-6 is present universally in tonsils of children, and tonsillar epithelium may be an important viral reservoir in latent infection.

Are there histopathologic characteristics particular to fulminant hepatic failure caused by human herpesvirus-6 infection? A case report and discussion.

An 8-month-old boy was admitted to a neighboring hospital for severe liver dysfunction and drowsiness 4 days after a diagnosis of exanthem subitum. A diagnosis of fulminant hepatic failure was made, and liver biopsy was performed during the acute stage. The presence of human herpesvirus-6 variant B (HHV-6B) DNA was shown in liver tissue by polymerase chain reaction (PCR) and in the endothelium of the portal vein by in situ hybridization (ISH). Histologic examination showed microvesicular steatosis resembling that of Reye's syndrome, even though aspirin had not been prescribed. We considered HHV-6 to be the causative agent in this case and report what is perhaps the first precise histologic description of fulminant hepatic failure caused by HHV-6.

[HHV 6,7 and 8. Recently discovered herpesviruses explain the etiology of well-known diseases]. / HHV 6, 7 och 8. Nyupptäckta herpesvirus förklarar etiologin till välkända sjukdomar.

Three new members of the family of human herpesviruses (HHVs) have been identified in less than a decade, HHV 67 and 8. HHV-6 and HHV-7, both infecting T-lymphocytes and phylogenetically related to cytomegalovirus, were identified as causative agents of exanthema subitum. In addition, HHV-6 has been reported to manifest central nervous system tropism and to be frequently detected in normal brain tissue, but has also been associated with febrile seizures. HHV-7 has been suggested to be involved in the development of pityriasis rosea, but has also been found to occur in normal dermal tissue. HHV-8, related to Epstein-Barr virus and infecting B-lymphocytes, was the first herpesvirus to be identified with molecular techniques. Recent research has been focused on the involvement of proteins expressed by HHV-8 in the pathogenesis of two rare tumours, Kaposi's sarcoma and body-cavity B-cell lymphomas.

The new herpesviruses: emerging pathogens of dermatological interest.

OBJECTIVES: To discuss the current knowledge of 3 recently discovered human herpesviruses (HHV-6, HHV-7, and HHV-8), and to provide a dermatological point of view. DATA SOURCES: References identified from bibliographies of pertinent articles in the English language. STUDY SELECTION AND DATA EXTRACTION: Articles were selected according to their impact factor and the interest for dermatologists. DATA SYNTHESIS: As the other members of the family Herpesviridae, HHV-6, HHV-7, and HHV-8 may cause a primary infection, establish latent infection in a specific set of cells of their host, and then reactivate if conditions of altered immunity develop. The main pathological conditions associated with them are discussed. CONCLUSIONS: Human herpesvirus 6, HHV-7, and HHV-8 have provided new insights in some dermatological diseases. Although new studies are needed, they may have a profound impact on dermatology in the years to come.

[Recently discovered herpes viruses explain the etiology of well-known diseases]. / Nyupptäckta herpesvirus förklarar etiologin till välkända sjukdomar.

Three new members of the family of human herpesviruses (HHVs) have been identified in less than a decade, HHV 6 7 and 8. HHV-6 and HHV-7, both infecting T-lymphocytes and phylogenetically related to cytomegalovirus, were identified as causative agents of exanthema subitum. In addition, HHV-6 has been reported to manifest central nervous system tropism and to be frequently detected in normal brain tissue, but has also been associated with febrile seizures. HHV-7 has been suggested to be involved in the development of pityriasis rosea, but has also been found to occur in normal dermal tissue. HHV-8, related to Epstein-Barr virus and infecting B-lymphocytes, was the first herpesvirus to be identified with molecular techniques. Recent research has been focused on the involvement of proteins expressed by HHV-8 in the pathogenesis of two rare tumours, Kaposi's sarcoma and body-cavity B-cell lymphomas.

Apoptosis of CD4+ T lymphocytes in human herpesvirus-6 infection.

The present authors have recently reported that inoculation with human herpesvirus-6 (HHV-6) renders CD4+ T lymphocytes susceptible to apoptosis in vitro. In order to confirm that apoptosis of CD4+ T lymphocytes also occurs in HHV-6 infection in vivo, apoptosis of lymphocytes isolated from nine patients with exanthem subitum and from an adult patient with severe HHV-6 infection was examined. Peripheral blood mononuclear cells were cultured for 3 days and apoptosis of lymphocytes was then examined by flow cytometry of propidium iodide-stained DNA. The percentages of hypodiploid DNA, indicating apoptosis, in lymphocytes from 10 patients with HHV-6 infection were significantly higher than those from five infant patients with noninfectious diseases and five healthy adults (P < 0-0002). DNA fragmentation was also detected by agarose gel electrophoresis in lymphocytes from patients with HHV-6 infection. Apoptosis appeared to occur predominantly in CD4+ T lymphocytes and HHV-6 was isolated from the CD4+ T lymphocyte fraction. These data demonstrate that HHV-6 renders CD4+ T lymphocytes susceptible to apoptosis in vivo.

Distribution of human herpesvirus 6 and varicella-zoster virus in organs of a fatal case with exanthem subitum and varicella.

The distribution of human herpesvirus 6 (HHV-6) and varicella-zoster virus (VZV) was examined in autopsy samples from a fatal case with both virus infections. A 9-month-old boy developed convulsive seizures followed by macular skin rashes, rapidly progressed to brain death, and died 15 days after the onset, when signs of varicella were noted. An isolation of HHV-6 from blood and evaluation of antibody activities to various viral agents including HHV-6 were performed before his death. Postmortem examinations included: (i) isolation of HHV-6 and VZV from tissues or organs; (ii) detection of both virus antigens in tissues or organs by an indirect immunofluorescent assay using monoclonal antibodies to both viruses; (iii) amplification of both viruses and human herpesvirus 7 DNA sequences by a nested polymerase chain reaction assay; and (iv) endonuclease digestion of amplified products of HHV-6 DNA for differentation of variants A and B. Human herpesvirus 6 DNA was detected in peripheral blood mononuclear cells (PBMC) and plasma obtained at the eruptive stage but present only in PBMC 15 days after, indicating the primary infection with HHV-6, although the virus was not isolated from the same blood sample and a significant rise in the antibody titers to HHV-6 was not observed. Both virus antigens and DNA were detected in various tissues or organs obtained at autopsy, but only VZV was isolated from these samples, suggesting disseminated infection with both viruses in an infant. All the amplified products of HHV-6 DNA were variant B. Among the findings for the distribution of virus antigens, it was noteworthy that HHV-6 antigen was demonstrated in the endothelial cells of small vessels in the frontal lobe of the brain. There was no evidence of HHV-7 infection. These data indicate that the primary HHV-6 infection closely followed by the primary VZV infection had the potential hazard of an unexpected and apparently life-threatening event, in which disseminated infections with both viruses were noted in multiple tissues or organs including the brain.

HHV-6 antigen and viral DNA detected in cervical cells from archived tissue using histochemical staining and hybridization.

BACKGROUND: Human herpesvirus type 6 (HHV-6), an ubiquitous virus, is the causative agent for exanthem subitum. The virus is frequently associated with lymphoproliferative disorders and other diseases. Recently, we have reported the frequent presence of HHV-6 in oral carcinoma and the present study extends the observation to cervical carcinoma. OBJECTIVE: To examine the presence of HHV-6 in cervical carcinoma. STUDY DESIGN: Formalin-fixed, paraffin-embedded cervical carcinoma tissues were examined for the presence of HHV-6 by immunohistochemistry using two monoclonal antibodies that react to HHV-6-encoded p41/38 and gp116/64/54. In situ hybridization with variant-specific probes were used to type the HHV-6 DNA sequences present. RESULTS: A total of 14/26 (53.9%) carcinoma tissue specimens and 5/8 (62.5%) normal tissue specimens were positive for viral antigens. In situ hybridization studies revealed the presence of HHV-6 DNA sequences in 10/26 (38.5%) carcinoma tissue specimens and 1/8 (12.5%) normal tissue specimens. In the normal tissue, the HHV-6 was present in the endocervical ciliated columnar-epithelial cells and some cells in the subepithelial mucosa but in the carcinoma, the transformed cells were positive for the virus. CONCLUSIONS: HHV-6 viral proteins and DNA were found in more than one third of the cervical tissue examined suggesting possible viral expression in these tumours. The significance of the distribution and role of the HHV-6 in cervical tissue remains unclear. Since HHV-6 has an oncogenic potential, the virus may cooperate with other transforming agents for the progression of the disease.

Human herpesvirus 7 infection associated with central nervous system manifestations.

The clinical features of infection with human herpesvirus 7 (HHV-7) are not well described. Exanthem subitum is the only illness that is confirmed to be caused by HHV-7. We report two children who had exanthem subitum associated with central nervous system manifestations. Two strains of HHV-7 were isolated sequentially from peripheral blood mononuclear cells and saliva of the some child who had exanthem subitum complicated with acute hemiplegia in childhood. Two strains were confirmed to be HHV-7 by means of monoclonal antibodies to human herpesvirus 6 (HHV-6) and HHV-7, polymerase chain reaction, and DNA analysis. During the convalescent period, the antibody titer to HHV-7 rose from less than 1:10 to 1:320, whereas the antibody titer to HHV-6 remained less than 1:10. Another child with exanthem subitum complicated by acute hemiplegia had serologic evidence of primary HHV-7 infection. These two cases demonstrate a new relationship between HHV-7 and central nervous system symptoms.

Case report: Gianotti-Crosti syndrome associated with human herpesvirus-6 infection.

We report a case of Gianotti-Crosti syndrome associated with human herpesvirus-6 (HHV-6) infection. An eight-month-old girl developed monomorphous papules on her cheeks, buttocks, and extremities after the subsidence of exanthema subitum. Viral antibody analysis confirmed primary HHV-6 infection. HHV-6 may be added to the list of causative agents of Gianotti-Crosti syndrome.