Which is the most common preceding infection in bone marrow failure syndromes?

Most common infection preceding bone marrow failure syndrome is hepatitis. It is usually sero negative ( non-A, non- B, non - C ). It accounts for 5% of etiologies. Parvo virus can cause pure red cell aplasia, but it doesn't usually cause generalised bone marrow failure. Ref: Harrison's principles of internal medicine, 21st edition, page 664