THE stress of spaceflight weakens astronauts' immunity and increases their risk of passing infections to one another. The findings diminish prospects for crewed missions to planets such as Mars, unless ways can be found to boost the astronauts' immune systems.
Satish Mehta and his colleagues at NASA's Johnson Space Center in Houston measured levels of Epstein-Barr virus (EBV) in saliva samples taken from 10 astronauts before, during and after a series of space shuttle missions. Many of us carry EBV, but it normally stays dormant in our white blood cells, and is only activated when people are stressed.
Mehta found EBV in 13 per cent of the samples, but the number of copies of the virus increased dramatically while the astronauts were in space. Samples from astronauts testing positive for EBV contained more than 40 times as many viruses during a shuttle flight than before or afterwards. "Don't kiss an astronaut," jokes Mehta.
Although EBV is normally harmless, it can cause glandular fever and has been associated with Burkitt's lymphoma, a type of cancer common in Africa. Mehta fears that other, more dangerous viruses could also be transmitted more easily by stressed astronauts. In preliminary analyses, he has already found elevated levels of cytomegalovirus in saliva samples taken on the shuttle. This virus can cause blindness in immunosuppressed people.
"When these astronauts go up, they are under huge stress, the greatest being the fear they won't come back," says Mehta. "It's crowded, cramped and tiring, and if crew members breathe out virus, it hangs around in microgravity and can easily be breathed in."
The solution might be for the astronauts to take antiviral drugs before and during missions, or to give saliva samples during the flight so that stressed crew members can be identified and told to take a break.
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Contact: Claire Bowles
claire.bowles@rbi.co.uk
44-171-331-2751
New Scientist
9-Jun-1999