Comments on the article 'Borna Disease Virus in Human Brains with a Rare Form of Hippocampal Degeneration But Not in Brains of Patients with Common Neuropsychiatric Disorders,' by M. Czygan, W. Hallensleben et al, published in the 1999 issue of the 'Journal of Infectious Diseases.' Detection of Borna disease virus nucleic acid in patients with chronic fatigue syndrome.