Clinical Significance of Human Herpesvirus 6 and 7 Infection in a Tertiary Hospital: a Case-Control Study

Author(s): Pablo Borque, Juan Carlos Galán, Beatriz Romero, Francesca Gioia, Rosa Escudero, Pilar Martín-Dávila Santiago Moreno, Jesús Fortún

Background: Human herpesviruses (HHV)-6 and HHV-7 are ubiquitous viruses with a global seroprevalence of around 90%, but their pathogenic significance remains unclear.

Methods: For 2 years, at our center, the presence of HHV6 and 7 DNA was investigated by PCR assay in blood, CSF, or other fluids. Epidemiological and clinical variables were collected from these patients and compared with those obtained in a negative-control cohort. Molecular detection of herpesvirus was performed using The Clart Entherpex kit (Genomica, Coslada, Spain), allowing simultaneous detection and identification of the eight human herpesviruses (HSV-1 to HHV-8) and Enterovirus (echovirus, poliovirus, and coxsackievirus).

Results: All patients, cases, and controls were immunocompromised and had similar baseline clinical conditions. For all of them, molecular amplification of HHV-6 or 7 was requested as a diagnostic complement from different clinical pictures, mainly neurological symptomatology (80%). Corticosteroid treatment and viral or bacterial co-infection were independently associated with HHV-6 or 7 infections. When the impact of both viruses was analyzed independently, it was confirmed that HHV-6 was independently associated with higher 1-year mortality.

Conclusion: HHV-6 replication in CSF or blood may be a surrogate marker of mortality in the medium term in immunocompromised patients.