Stunned scientists have discovered a thriving ecosystem of "infectious organisms" aboard the International Space Station and have ordered urgent tests to determine if the "space bugs" are virulent enough to cause health problems for astronauts.

Stunned scientists have discovered a thriving ecosystem of “infectious organisms” aboard the International Space Station and have ordered urgent tests to determine if the “space bugs” are virulent enough to cause health problems for astronauts.

A NASA team found five different varieties of space bugs, or Enterobacter, which are similar to bugs found in hospitals down here on Earth.

However while the bugs are similar to bugs found on Earth, they are different in fundamental and possibly highly dangerous ways.

The toilet of the International Space Station was one of the main sites of infection along with the exercise area.

Researchers calculated that there is a “79% probability that they may potentially cause disease“, although analysis has only been carried out on dead samples at this stage so this risk could prove to be even higher following further research.

Astronauts might be exposed to space diseases previously unknown to humans.

Metro reports: It’s feared some of the bacteria could be drug-resistant, meaning they could pose more of a threat to astronauts because traditional treatments would not work properly.

However, researchers stressed the drugs are not harmful to humans currently aboard the ISS.

Dr Nitin Singh, who has just published a report on the bugs, said: ‘Given the multi-drug resistance results for these [bacteria] and the increased chance of pathogenicity we have identified, these species potentially pose important health considerations for future missions.’

Luckily, the tiny organisms do not appear to be virulent enough to make humans ill at this stage, although they could evolve into a more dangerous form.

It is important to understand that the strains found on the ISS were not virulent, which means they are not an active threat to human health, but something to be monitored,’ Dr Singh added.

It is feared the space bugs may be drug resistant, although more tests are required to confirm this.

Dr Kasthuri Venkateswaran, senior research scientist at the Jet Propulsion Laboratory Biotechnology and Planetary Protection Group and the corresponding author of the study, said three of strains belonged to a species which caused illness in newborn babies here on Earth.

The bugs also infected a ‘compromised patient’, which means they are likely to have been suffering from a condition already which made them susceptible to infection.

Scientists now want to perform further tests to decide how much of a threat the bacteria pose to astronauts.