HHV-6 in Transplant Patients

HHV-6 reactivates in transplant patients who are immunosuppressed to prevent rejection of the graft. Consequences of HHV-6 reactivation include CMV reactivation, bone marrow suppression, central nervous system dysfunction, idiopathic pneumonitis, severe graft host disease, hepatitis fulminant liver failure and increased mortality.

Central nervous system complaints include memory loss, fatigue and difficulties with cognitive processing. Seizures are common and MRI studies classically show involvement of the medial temporal lobes. These side effects generally occur 3-4 weeks after the transplant. HHV-6 is the most common cause of CNS dysfunction after transplants. Some experts, such as Dr. Per Ljungman at the Karolinska Institute, recommend a spinal tap for such patients and treat patients with 6-8 weeks of IV ganciclovir or foscarnet if any virus is found in the spinal fluid, even if it is a very low copy number.

In the US, HHV-6 reactivation creates the biggest problem with stem cell or bone marrow transplant patients. This is because most US transplant patients are now given preventative treatment with a potent antiviral, valganciclovir (oral ganciclovir). This is not the case in Europe and other parts of the world where preventive treatment is not the standard.