Molecular detection of human herpesvirus 7 DNA in cerebrospinal fluid from adult patients with neurological disorders

Neurological manifestations associated with HHV-7 have been described in primary infection in children, and very occasionally in immunocompromised adult patients. However, the role of HHV-7 reactivation as a cause of central nervous system (CNS) diseases in immunocompetent adults has not yet been defined. We retrospectively analyzed clinical and microbiological features of adults with neurological symptoms who underwent lumbar puncture and a multiplex polymerase chain reaction (PCR) for herpesviruses (HHV-1–8) and enteroviruses performed in cerebrospinal fluid (CSF), during a 4-year period. A total of 251 subjects were included. Mean age was 55 years, ranging 15–89. Globally, HHV-7 DNA was detected in CSF in 14 patients (5.6%). It was detected in 1 of 36 patients with microbiologically confirmed CNS infections, and in 7 of 172 patients with diagnoses of non-infectious neurological disorders (Specificity 0.96, 95% confidence interval 0.93–0.99). Additionally, HHV-7 DNA was detected in 6 of 21 patients (28.6%) with probable CNS infections (compatible clinical syndrome and CSF changes) in the absence of other causative agent: four meningitis, one myelitis, and one encephalitis. Treatment with foscarnet was effective in achieving improvement of symptoms and clearance of HHV-7 DNA in CSF in the cases of encephalitis and myelitis, while ganciclovir was ineffective in the case of encephalitis. Our results show that HHV-7 reactivation may cause CNS disease in immunocompetent adults and that detection of HHV-7 DNA in CSF as a false-positive result or as asymptomatic reactivation in adult patients with neurological diseases is uncommon. Foscarnet seems the first-line treatment for HHV-7 CNS disease.