Encephalitis associated with human herpesvirus-7 infection in an immunocompetent adult

Abstract

BackgroundPrimary Human herpesvirus-7 (HHV-7) infection usually occurs during childhood and causes several clinical manifestations: mainly exanthem subitum (roseola infantum), followed by a lifelong latent state with possible reactivation in case of immunodeficiency. Nevertheless, some considerably different approaches exist regarding the natural history of HHV-7 and the possible consequences of HHV-7 infection in immunocompetent adults. In particular, little is known about its pathogenic role in central nervous system (CNS) disease in nonimmunosuppressed adults. Specifically, in case of encephalitis, it is important to distinguish between infectious encephalitis and postinfectious encephalomyelitis for the management of patientsCase presentationWe describe here a case of encephalitis associated to human herpesvirus-7 with associated polymyeloradiculopathy in an immunocompetent patient which may contribute to the delineation of the approach to a patient profile with a similar clinical presentation and evolution to those presented in the literature.ConclusionsThis case may alert clinicians to consider this specific etiology in the differential diagnosis of encephalopathy in patients with suspected infectious encephalitis who do not respond to acyclovir or in patients who develop acute polymyeloradiculopathy, considering that HHV-7 may be a pathological factor and that a timely diagnosis is crucial for the early administration of specific treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-017-0764-y) contains supplementary material, which is available to authorized users.

Extracellular vesicles: novel vehicles in herpesvirus infection

“…Nevertheless, the pathogenic role of HHV-7 for non-immunosuppressed adults in diseases of the central nervous system still needs to be explored, and HHV-7 is possibly an etiological agent of suspected infectious encephalitis in individuals who do not respond to acyclovir (Parra et al, 2017). There is no published report on the roles of exosomes in HHV-7 infection.…”

“…HHV-7 infection commonly occurs in infants or during childhood and may cause symptoms in cases of immunodeficiency after reactivation from a latent infection (Parra et al, 2017;Riva et al, 2017). Nevertheless, the pathogenic role of HHV-7 for non-immunosuppressed adults in diseases of the central nervous system still needs to be explored, and HHV-7 is possibly an etiological agent of suspected infectious encephalitis in individuals who do not respond to acyclovir (Parra et al, 2017).…”

“…Closely related to HCMV, HHV-6 is a notable beta herpesvirus and can cause primary infection or be activated from latency in liver transplant recipients (Parra et al, 2017). HHV-6 is divided into two distinct species:…”

Herpesvirus Infections of the Central Nervous System

“…106 A recent summary of immunocompetent adults with acute HHV-7 and neurological signs included the following presentations: encephalitis with or without flaccid paralysis, acute myeloradiculopathy, encephaloradiculomyelitis, and acute myelitis. 107 In these patients, the diagnosis was made based on the absence of alternative diagnoses and the presence of HHV-7 DNA identified by PCR of CSF or, in two cases, a rise in HHV-7 antibody titers in the CSF, indicating intrathecal production. 107 The authors postulated that the illness was due to HHV-7 reactivation rather than primary infection in around half of patients.…”

“…107 In these patients, the diagnosis was made based on the absence of alternative diagnoses and the presence of HHV-7 DNA identified by PCR of CSF or, in two cases, a rise in HHV-7 antibody titers in the CSF, indicating intrathecal production. 107 The authors postulated that the illness was due to HHV-7 reactivation rather than primary infection in around half of patients. The challenge for diagnosing encephalitis or myelitis through the presence of HHV-7 in the CSF is that the virus has been detected in normal brain tissue from patients who died of unrelated causes in one autopsy series.…”