The diagnostic complexities of human herpesvirus 6 (HHV-6) infections.

Human herpesvirus 6 (HHV-6) is a common virus which is typically acquired early in childhood, and like other herpesviruses, can induce lifelong latency. While healthy individuals are not at risk of disease, immunosuppressed individuals such as those receiving hematopoetic stem cell transplantation are at substantial risk of morbidity and non-relapse mortality. Swift diagnosis and treatment remain crucial for the timely management of infections and reduce the severity of complications. A range of diagnostic approaches to detect HHV-6 have been established, the most common of which include PCR and serology; however, substantial challenges remain. Namely, existing diagnostic techniques struggle to differentiate between active HHV-6 infection, latency and chromosomal integration of HHV-6, which occurs in around 1 % of the population. Here, we discuss the established and emerging diagnostic tools for HHV-6, their strengths and limitations, and considerations for future diagnosis of this challenging viral pathogen.