A VERY important, albeit unpleasant, discovery has come to light: biologists at the University of Michigan studying raw human sewage found that it is home to thousands of novel, undiscovered viruses, some of which could relate to human health.

While the research is significant, it doesn’t come as much surprise given that of the hundreds of millions of viruses we already know of, only about 3,000 have been studied in any great detail. Couple this with the number of living micro organisms all around us (there are on average 400 species of bacteria living in the human colon alone) and all of a sudden, planet earth feels like it’s not really ours at all. We’re just vessels for a much tinier but all-pervasive dominant species.

Why we know so little about our overlords is down to a few simple reasons. “Most of everything is made up of bacteria,” explains Dr Patrick Collins of the Ryan Institute at NUI Galway. “There’s bacteria everywhere – there are just so many and they’re constantly evolving so it would be extremely difficult to try and study them all. Apart from anything, there isn’t the money to do so.”

When it comes to down to it, necessity is the mother of invention. “We tend to study the micro organisms that either provide some use for us or pose a threat,” explains Prof Paul Engels of the UCD School of Biomolecular Biomedical Science.

While their positive, practical uses are known (washing powder, probiotic yoghurt, etc), it is the nasty side of micro organisms that tends to lead to them getting bad press.

"Everybody thinks E Coliis bad but we've been living with it forever," says Engel. "What's happened is that a new strain has emerged with pretty lethal consequences. There is always the possibility that something which is not now a threat can become one in the future."

While we are all in a constant state of evolution, at the level of the micro organism that turnover is more rapid and the potential for something new and deadly is always possible.

The National Virus Reference Laboratory, based in UCD, is responsible for the fight against threatening organisms here. Established 30 years ago, it works closely with the department of medical microbiology at the university, so much so that in the past year, both entities have been incorporated into the Centre for Research into Infectious Diseases.

“We test around half a million samples a year for a range of viral infections,” explains Dr Jeff Connell, assistant director of the laboratory.

“But we have a dual function: one is to screen patients for infection; the second is to confirm results in the laboratory of screening tests. Once an infection has been identified we have various methodologies to treat it.”

The work of the lab has become increasingly effective in the past decade thanks to advances in technology. “I’ve been involved in virology for over 25 years,” says Connell. “In the past 15 years, though, there’s been an explosion in methodology and technology. We can look at the acute antibody responses to infection while at the same time looking at actual viruses themselves through molecular methods.”

While precautions are in place to facilitate the study and containment of threatening micro organisms and viruses, it is an area of science so expansive that keeping on top of what’s out there would be almost impossible.

Not only are they dominant in numbers but many organisms can thrive in conditions where humans wouldn’t last a second.

Extremophiles are organisms that live in places as unusual as on the sides of hydrothermal vents at the bottom of the Atlantic Ocean, or within active volcanoes. International drilling companies have found evidence of living organisms two miles down into the earth. These organisms are taking adaptation to a whole new level.

Couple this with the potential arrival of bacteria from space, and it’s hard to see how we could ever win the battle to contain them.

In 1996, bacteria-like structures were believed to have been found on a meteorite that came from Mars. The original hypothesis was they were in fact bacteria but, to quote Carl Sagen, “extraordinary claims require extraordinary evidence”. So the discoverers proceeded with caution.

“While the structures resembled bacteria, they were much smaller than our terrestrial bacteria – about 100 nanometres long,” explains Dr Jane Irwin of UCD. “But there was other evidence to suggest they were bacteria: they contained an iron oxide mineral called magnetite, which is used by terrestrial bacteria almost as a magnetic compass.”

To date, no agreement has been reached on whether or not the structures are bacteria,

There are some theories which suggest the existence of another world of even tinier entities beyond the world of the micro organisms, bacteria and viruses we’re currently aware of.

“Work in this area really still is in its infancy,” says Dr Kevin Divine of the London Metropolitan University. “But there may very well be what’s known as a ‘shadow biosphere’ among us with even smaller microbes living in environments too small for us to see, which would be truly exciting.”

Armageddon: Could a global pandemic end civilisation?

HOW CLOSE are we to a deadly global pandemic breaking out? In the cinemas at the moment, Steven Soderbergh's film, Contagiondeals with a deadly new virus that spreads worldwide, threatening to wipe civilisation off the face of the earth. The director gathered the expertise of several virologists who had worked on controlling the Sars, swine and avian flu pandemics in order to bring as much realism to the movie as possible. Pandemics like this have happened before. Could they happen again?

In order for a super virus to arise – like the Spanish flu of 1918 – it would need three distinct properties, explains Dr Kevin Divine of the London Metropolitan University.

“It needs to be easily transmittable like a cold or flu,” he says. “Secondly, it needs a long latency period between infection and the onset of the disease, like HIV. Thirdly, once the disease sets in, it must have a high mortality rate [like Ebola which has an 80-90 per cent death rate].

“Combining these factors together in a modern context with the level of global communication and contact now made on a daily basis and you would have an Armageddon situation on your hands,” he says.

The fact that existing deadly viruses haven’t already resulted in a major culling of the human species is down to one of these three properties being missing.

“If you look at some of the severe viruses already here, like Ebola, you’ll see that the mortality rate for that virus is in fact higher than HIV,” says Divine. “It is what’s known as a Category 5. What gives us an advantage over the Ebola virus, however, is that it has a very short time between infection and the onset of disease, which means it can be isolated. In the case of Aids, on the other hand, the onset of the disease is slow, so difficult to identify. But the virus is not as easily spread as something like Ebola.”

Should a new threat present itself, it will more than likely have spread from another species.

“There could be other viruses that reside in closely related species – monkeys and apes, for example – that we don’t know about,” says Divine. “If they jump the species barrier, then we have a problem. That’s usually how a super virus begins.”