Reactivation and shedding of cytomegalovirus in astronauts during spaceflight

The reactivation of cytomegalovirus (CMV) in 71 astronauts was investigated , using polymerase chain reaction. A significantly greater (P < .0001) shed ding frequency was found in urine samples from astronauts before spacefligh t (10.6%) than in urine from the healthy control subject group (1.2%). Two of 4 astronauts studied during spaceflight shed CMV in urine. A significant increase (P < .0001) in CMV antibody titer, compared with baseline values, was also found 10 days before spaceflight. CMV antibody titer was further increased (P < .001) 3 days after landing, compared with 10 days before the mission. Significant increases in stress hormones were also found after la nding, These results demonstrate that CMV reactivation occurred in astronau ts before spaceflight and indicate that CMV may further reactivate during s paceflight.