Astronauts have been actively involved in human space missions since the 1960s – and space travel is only advancing. Despite NASA effectively mastering human spaceflight, the more these methods are developed, new problems will arise. Among these are the implications of extended space travel, as the human body undergoes certain changes which make it more susceptible to infection. Viruses, on the other hand, only become more powerful.
What diseases can astronauts catch?
NASA astronauts experience a cocktail of effects which cause their immune systems to underperform, including weeks of microgravity, cosmic radiation, extreme G-forces, and an altered sleep-wake cycle.
Leonard Mermel, Professor of Medicine, at Brown University’ Warren Alpert Medical School, conducted an extensive study into the problems faced by future space travellers.
He specifically focussed on the risks associated with outer-space travel lasting two years.
Among infectious agents he has warned of are fungi, microbes and parasites.
He said: “The internal environment of a spacecraft or space station can become heavily contaminated with microbes, and free-floating condensate has been found to harbour numerous bacteria, fungi, and even protozoa (parasites).
“Microgravity affects the aerobiology of the aerosols that are created from a cough or sneeze or during speech.
“Particles remain airborne until they are inspired, swallowed, contact an otherwise absorbable surface, or are ideally promptly removed by an air filtration system.
“The presence of these aerosols affects the risk of person-to-person transmission of viruses such as influenza and even bacteria such as S aureus (which causes staph infections).”
Dr Satish Mehta warned that herpes was among those diseases which was affecting longhaul space travel – although the stufy only refers to a reactivation of the virus, rather than a new virus developing in space.
And while only a small proportion of the astronauts develop symptoms as a result of the dormant virus awakening, it could spell danger for longer spaceflight missions – for instance to Mars.
He said: “To date, 47 out of 89 (53 percent) astronauts on short space shuttle flights, and 14 out of 23 (61 percent) on longer ISS missions shed herpes viruses in their saliva or urine samples.
“These frequencies – as well as the quantity – of viral shedding are markedly higher than in samples from before or after flight, or from matched healthy controls.
“Only six astronauts developed any symptoms due to viral reactivation,” said Dr Mehta. “All were minor.”
Another type of bacteria which thrives in space is salmonella.
NASA conducted studies on the bacteria where they brought samples from Earth into space for a short period before returning to Earth.
They found the result was salmonella becoming several times more virulent, despite certain genes in the virus not being ‘turned on’.
This is because it relies on something called ‘fluid shear’, which in space is almost non-existent due to low gravity.
This allows the salmonella to ‘bloom’ effectively.
Doctor Mermel issued a series of suggestions on what should be done to protect people travelling in space.
He concluded: “If clinically significant immune dysfunction is documented, this, along with alterations in bacterial physiology during spaceflight, will create challenges to successful human missions.
“Attention to basic infection prevention and control practices should help to reduce the risk posed to astronauts.
“Research funding should be available to address transmission dynamics of microbes in microgravity and other unanswered questions.“