Research by Nasa has revealed that space travel causes the reactivation of dormant herpes viruses, posing a significant health risk for astronauts on missions to Mars and beyond.

Published in Frontiers in Microbiology, the study revealed that herpes viruses reactivate in more than half of crew who travelled aboard Space Shuttle and International Space Station missions.

Although only a small proportion of the astronauts develop symptoms due to the reactivated viruses, the fact that reactivation rates increase with spaceflight duration could pose risks to missions such as Mars.

Study author and Johnson Space Center researcher Dr Satish Mehta said: “Nasa astronauts endure weeks or even months exposed to microgravity and cosmic radiation – not to mention the extreme G forces of take-off and re-entry. This physical challenge is compounded by more familiar stressors like social separation, confinement and an altered sleep-wake cycle.”

“During spaceflight, there is a rise in the secretion of stress hormones like cortisol and adrenaline, which are known to suppress the immune system.”

As part of the study, the researchers analysed saliva, blood and urine samples to study the physiological impact of spaceflight.

The samples were collected from astronauts before, during and after spaceflight.

Mehta added: “During spaceflight, there is a rise in the secretion of stress hormones like cortisol and adrenaline, which are known to suppress the immune system. In keeping with this, we find that astronaut’s immune cells, particularly those that normally suppress and eliminate viruses, become less effective during spaceflight and sometimes for up to 60 days after.”

How disruptive will the COVID-19 outbreak be on aerospace supply chains?

View Results

Loading ... Loading ...

The suppression of the immune system due to the stress caused by spaceflight reduces the ability of the astronauts’ bodies to prevent dormant viruses from reactivating.

According to the tests, it was found that 53% of the astronauts on short space shuttle flights and 61% on longer ISS missions shed herpes viruses in their saliva or urine samples.

Mehta said: “These frequencies, as well as the quantity, of viral shedding are markedly higher than in samples from before or after the flight, or from matched healthy controls.”

The study has detected four of the eight known human herpesviruses, including the varieties responsible for oral and genital herpes (HSV), chickenpox and shingles (VZV), as well as cytomegalovirus (CMV) and Epstein-Barr virus (EBV).

Furthermore, Mehta argued that the agency needs to develop countermeasures to viral reactivation to ensure the success of deep-space missions.