Delayed Primary HHV-7 Infection and Neurologic Disease

Abstract

BACKGROUND: Primary human herpesvirus 7 (HHV-7) infection occurs almost universally during the first 5 years of life and is rarely accompanied by central nervous system (CNS) symptoms such as febrile seizures. The present retrospective study investigated the role of primary HHV-7 infection in CNS disease in children, including adolescents. METHODS: The study included all children who had neurologic disease aged younger than 18 years seen at the Hospital for Sick Children, Toronto, Canada, between April 1, 1998 and December 31, 2011, whose cerebrospinal fluid (CSF) was found by polymerase chain reaction to contain HHV-7 DNA. Where sera were available, HHV-7 IgG antibody titers and avidity were measured to differentiate primary from past infection. RESULTS: HHV-7 DNA was detected in the CSF of 57 (1.9%) of the 2972 children tested. In 3 adolescents primary HHV-7 infection (low avidity IgG) was confirmed as the cause of neurologic disease, 2 who had encephalitis and 1 who had Guillain-Barré syndrome. Eighteen children had possible HHV-7 disease (no alternative cause identified and indeterminate antibody result or serum not available), 7 encephalitis, 8 meningitis, and 3 demyelinating disorders. HHV-7 disease was excluded in 36 children on the basis of past infection (high IgG avidity) and/or an alternative cause. CONCLUSIONS: Primary HHV-7 infection delayed into adolescence can cause serious neurologic disease. HHV-7 DNA in CSF alone is insufficient to prove an etiologic association. Combining CSF polymerase chain reaction with serology is essential to prove primary infection when investigating HHV-7 CNS disease.

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

“…The detection of HHV-7 DNA in the patient’s CSF concomitant with neurological disease in association with the exclusion of all alternative etiological causes (according to the clinical practice guidelines of the Infectious Diseases Society of America [3]) supported HHV-7 as the possible cause of the encephalitis, based on the criteria that were established by Schwartz et al [4]. As a consequence of antibody avidity could not be determined in our laboratory to differentiate between primary and past infection, we can not certainly establish whether encephalitis associated to HHV-7 infection in our patient was secondary to late primary infection or reactivation.…”

Clinical impact of primary infection with roseoloviruses

“…While these studies are relatively small in size, it appears that HHV-7 primary infection has the potential for severe complications similar to HHV-6. Recent evidence has also linked delayed HHV-7 primary infection with severe neurologic complications, including encephalitis and Guillain-Barre syndrome [45]. …”

Polirradiculoneuritis aguda asociada a infección por Virus Herpes Humano 7 en un paciente adulto inmunocompetente

“…Posiblemente por analogía con otros virus herpes humanos, la primoinfección tardía puede causar presentaciones clínicas más severas que las infecciones primarias en la niñez 9 .…”