Human herpesvirus-7 associated recurrent encephalitis in an immunocompetent young man and successful foscarnet treatment

Background

Human herpesvirus type-7 (HHV-7) is a recently described herpesvirus, and neuroinvasion has been rarely reported. We describe recurrent encephalitis associated with HHV-7 in an immunocompetent host, who was successfully treated with foscarnet.

Case report

A 32-year-old man was transferred to our hospital from a local hospital because of a sudden onset of decreased mental status and intermittent abnormal behavior. He had been previously diagnosed with HSV-1 encephalitis and treated with acyclovir for 20 days; after two months, altered mental status and abnormal behavior occurred. Brain magnetic resonance imaging (MRI) on admission disclosed high-signal lesions involving the bilateral temporal lobe on T2 weighted imaging. We examined a variety of viral DNA in cerebrospinal fluid and serum by nested polymerase chain reaction.

Results

HHV-7 DNA was detected in both cerebrospinal fluid and serum, suggesting neuroinvasion by HHV-7. No other viral DNA was identified. After intravenous treatment with foscarnet sodium 2000 mg every eight hours for two weeks, the patient was significantly recovered except for a mild memory deficit. Follow-up brain MRI showed that the lesion had almost disappeared.

Conclusion

HHV-7 may cause meningoencephalitis in immunocompetent adults, and should be investigated as possible etiology in the treatment of resistant encephalitis patients. This case indicates that HHV-7 meningoencephalitis can be effectively eradicated by foscarnet treatment.