At 60 days post transplant , 73% of the spinal fluid tested for possible encephalitis was positive for HHV-6 in a recent review. By 100 days, that percentage was still high at 73%. Only 10% were positive for EBV and no other virus was positive in more than 3% of cases.
Investigators from several institutions analyzed the database of the Center for International Blood and Bone Marrow Transplant Research to determine the type of infections outcome of patients who test positive for a virus in the cerebrospinal fluid in the first 100 days. Infections such as CMV, adenovirus, varicella virus and herpes simplex virus represented only 3% each of the total infections. Slightly over half of the infections were in patients who had cord blood transplants.
Source: Abidi 2019, Bone Marrow Transplantation
At 60 days, the percentage of CNS infections positive for HHV-6 was even higher – 89%.
The median onset of a viral infection was at 31 days, with HHV-6 occurring at an average of 28 days and other viruses at a median of 80 days.
Only 45% had concurrent viremia, with the same virus detected in the spinal fluid and in plasma, and for HHV-6, the concurrence was lower at 34%. The authors speculate that one reason for the lack of concurrence is the finding by Zerr et al that plasma viremia in patient with HHV-6 encephalitis is short-lived, whereas the DNA can be detected for a longer period in the cerebrospinal fluid (Zerr 2002).
58% of patients with a central nervous system viral infection had a previous occurrence of acute graft vs. host disease.
Read the full paper: Abidi 2019