According to a NASA study, space travel can cause herpes viruses to resurrect in over half of the crew on board the Space Shuttle and International Space Station (ISS). The finding could endanger mankind’s future missions to Mars and beyond. While only a small percentage of developed symptoms, virus revival rates increased with spaceflight extent and could present a meaningful health risk on impending missions.

Satish K Mehta at NASA’s Johnson Space Center stated that NASA astronauts go through weeks and sometimes even months of being exposed to microgravity and cosmic radiation, along with acute G forces of take-off and re-entry. He stated that this physical challenge is aggravated by more familiar stressors such as social separation, repression and changed the sleep-wake cycle.

In order to study the physiological effect of spaceflight, researchers examined saliva, blood and urine samples collected from astronauts before, during and after their spaceflight. During spaceflight, there is an increase in the secretion of stress hormones such as cortisol and adrenaline, which are known to repress the immune system. Mehta stated that during the examination they found that astronauts immune cells, especially those that normally subdue and get rid of viruses become less compelling during spaceflight and sometimes for up to 60 days after.

According to the research published in the journal Frontiers in Microbiology, in the midst of this stress-caused amnesty on viral killing, dormant viruses resurrect and resurface.

The study showed that till date, 47 out of 89 (53%) astronauts during short space shuttle flights, and 14 out of 23 (61%) on longer ISS missions drop herpes viruses in their saliva or urine samples.

In general, four of the eight known human herpesviruses were detected.

These include the varieties responsible for oral and genital herpes (HSV), chickenpox and shingles (VZV) that remain lifelong in our nerve cells, as well as CMV and EBV, which take permanent but inconclusive residence in our immune cells during childhood.