27/04/2016 2:23 PM AEST | Updated 15/07/2016 12:52 PM AEST

Virus Hunters Follow One Gastro Bug's Rise And Demise To Make Way For A New Strain

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Map of the world highlighting Australia and New Zealand

The spread of one gastro strain has been traced from Sydney through Australia, into New Zealand and around the world, and now experts warn of its demise as a new viral threat approaches.

The highly contagious virus, named 'Sydney 2012', has been responsible for outbreaks in hospitals, aged care facilities, cruise ships and hostels since it was first discovered in, you guessed it, Sydney in 2012.

Sydney 2012 was one of the first gastro bugs to have its genome sequenced, which allowed researchers to follow its rise and, now, its demise.

What's a norovirus?

A type of highly infectious virus that causes gastroenteritis, including vomiting and diarrhea.

There are many different strains of norovirus and it can be spread through person-to-person contact, vomit and feces.

University of New South Wales professor Peter White told The Huffington Post Australia the virus' success would also be its undoing because every time someone was infected, they developed immunity.

"About 1.5 to 2 million Australians are infected with norovirus each year and those people then develop some level of immunity," White said.

"This strain is still dominant three or four years later and that's a good thing because we've probably got the highest level of herd immunity yet.

"What we tend to see is one strain will be dominant for about three years and then as herd immunity increases, incidences drop. Then another strain overtakes it and no one has any immunity.

"A new strain is coming to Australia, there's no doubt about that."

In other words, we're currently experiencing the calm before the s***storm.

"We've only recently had capabilities to predict a pandemic before it happens," White said.

"With Sydney 2012, we could let the whole world know it was a new strain three months before the pandemic struck."

To give you an idea of what a gastro outbreak is like, White and his team collect samples from all sorts of institutional outbreaks, mostly aged-care facilities and hospitals, but he said one cruise ship outbreak was particularly memorable.

"We just investigated ship with 800 people on board – I won’t say which ship – but there were 26 vomiting events including one in the swimming pool," White said.

Norovirus outbreaks on cruise ships are not uncommon.

"This is a very highly contagious virus anyway, but it's also one of the few viruses that spreads in vomit. If someone is sick, anyone within a range up to 10m can easily get sick as well.

"At that point, it’s quite impossible to avoid, and one quarter of those on board became sick."

White and his team has contributed to a PLOS One collection of data and analysis looking at the global burden of norovirus which found it was globally responsible for more than 200,000 deaths and causing a global economic burden of US$60 billion.

Check out the collection of information here.