Getting blasted into orbit is a stressful experience.
The whole space flight thing, apparently, causes enough stress to astronauts that it actually suppresses their immune systems. When that happens, all kinds of viruses — including herpes — can re-emerge.
This is the major finding of a recent study published in March in the journal Frontiers in Microbiology. It’s just one of the latest pieces of health research done on astronauts that scientists hope could someday help people back on Earth.
Researchers examined a total of 112 astronauts who had either flown on the Space Shuttle or spent time on the International Space Station. They found that 53 per cent of people who had been on short space shuttle flights and 61 per cent of people who were on longer ISS missions were shedding “one or more herpes viruses” in their saliva or urine — meaning they were potentially contagious.
It’s not that astronauts are especially riddled with germs; most people have herpes — about two-thirds of the world’s population has the kind that typically causes cold sores, according to the World Health Organization. Most of the time though, it stays dormant and doesn’t cause any symptoms.
But space presents some challenges. G-forces, microgravity, and circadian rhythm disruptions are all sources of stress for astronauts, said Dr. Chen Wang, a professor at the University of Toronto. And that stress makes astronauts immunocompromised, allowing viruses to come back, just like chickenpox might re-emerge as shingles in an older adult.
“We know those changes are an indication of a weakened immune system,” he said. “But we don’t know much about exactly what happened to the immune system and mediators during the flight.”
Wang has his own project with astronauts on the International Space Station, which is looking into that question.
He says he’s doing it for two major reasons. First, as space flights get longer — say, during a years-long mission to Mars — you can’t have the crew getting seriously ill. If scientists know what’s happening in astronauts’ bodies, they might be able to counteract it.
Secondly, he believes that research done on astronauts’ immune systems can help us understand what’s happening to immunocompromised patients on Earth.
“Space flight, in a way, provides a good model for a stress-affected immune system or aging,” he said.
Astronauts, it turns out, make excellent guinea pigs. They’re healthy people who are suddenly placed into a very controlled environment. Their lives are closely monitored, from what they eat to how they exercise and what they do during the day.
This simplifies experiments done on them, removing pesky variables that you might find with test subjects on Earth.
It’s hard to find people on Earth with just one environmental factor imposed on them, said Perry Johnson-Green, senior program scientist in life and physical sciences at the Canadian Space Agency.
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“For example, if someone’s inactive, they may also have a lot of nutritional issues where they’re maybe eating the wrong types of food, that sort of thing,” he said.
So if you’re trying to figure out which medical problems are caused by inactivity, it’s harder to tell with an average person whether something is due to their sedentary lifestyle, the food they eat, or their medical history.
“Whereas for astronauts, we know they have a very controlled diet. It’s a very healthy diet and so we can eliminate that as a factor. We know before they went to space they had a very good lifestyle. So there’s a lot of things we can eliminate right from the start.”
Inactivity, isolation, physical decline
Astronauts are especially good for testing the effects of inactivity, he said.
“We see a really interesting parallel there, basically because we have these very healthy, very fit astronauts that we send into space into what is really a very sedentary lifestyle.”
Experiments done by Canadian researchers have shown that short bursts of exercise aren’t enough to counteract the negative effects of minimal physical activity, and that there is an increased risk of fracture due to a loss of bone density as a result of weightlessness.
“The astronauts, when they return, have to be pretty careful for quite some months because they do have an increased fracture risk that recovers very slowly,” Johnson-Green said.
Researching astronauts helps further understanding of how prolonged inactivity might affect someone recovering from an immobilizing injury, for example, he said.
WATCH: Canadian astronaut David Saint-Jacques describes bodily adjustments in space
Astronauts up on the ISS are also extremely isolated — more than anyone else except, perhaps, a few Antarctic researchers.
“The crew members on the ISS, in particular, are completely isolated from their families and their co-workers, except for the co-workers on the station,” he said.
“This isn’t something that all Canadians face or all people on Earth face, but certain segments of society suffer from isolation. Having the ISS gives us a really controlled way to study the effects of isolation on people who are very fit otherwise.”
A study run by researchers at the University of British Columbia, along with the CSA, is looking into how astronauts cope by creating their own culture, and identifying what characteristics help make them adapt more successfully — something the CSA hopes could help workers in remote areas, or ease residents’ transition into nursing homes.
Many astronauts also have trouble walking when they get home — not just due to muscle atrophy, but because space travel messes up their vestibular system, which regulates balance and spatial orientation.
“Some astronauts, when they get back, are somewhat comfortable walking around and there are others that really take a couple of days before they really feel comfortable in walking around on their own,” he said. They usually recover in about two weeks, “then they’re allowed to drive again.”
There are many vestibular system disorders, and some researchers suggest that techniques that help astronauts might also help out ordinary patients.
Wang believes his immune system research, which he hopes will start collecting results later this year, is the first to monitor astronauts’ immune function while they’re still in orbit. The testing equipment used on board the space station might someday be used to shorten wait times for medical tests on Earth, according to the CSA, as well as to improve care in rural and remote areas.
“The first step is to know exactly what happens to the immune system. We are in this stage,” he said. “Then hopefully, we will find ways to help them counter those bugs, the virus activation.”
He signed up because of his expertise in spotting diseases through blood analysis, and also, “anything involving space flight is cool, so I’d be happy to do it.”