With new cases being reported here every day it's clear Australia is in the grip of a gastro outbreak, and its effects are severe.

The extreme virus, which is named norovirus, has public health officials like Professor Mark Ferson worried.

"We have been aware of outbreaks in nursing homes, hospitals, cruise ships and childcare centres from mid to late 2012," Professor Ferson said.

• Preventing childhood obesity
• Healthy child called 'fat and obese'
• Fighting fat with food

"It is extremely contagious," he warned.

University of New South Wales Professor Peter White discovered the virus in March last year. Since its appearance there's been a 400 per cent increase in cases in Victoria.

"Up to 70 per cent of the cases now, of gastro, we can find this virus," Professor White said.

Keeping your home germ free

"We do know from its genetic makeup that it is a combination of two viruses - one from an ancestor of a Dutch virus, the other from a Japanese virus discovered in 2007."

The virus strikes rapidly - one minute you can feel fine, and then next you'll experience some dizziness. Before you know it you'll have nausea, stomach cramps, diarrhoea and vomiting.

400,000 Australians are expected to be struck down this winter, but the disease hasn't stopped on our shores.

Today Tonight's latest health stories

According to Professor Ferson "it has obviously spread around the world."

1.2 million Britons have been infected by the virus, and hospital wards and childcare centres have closed, while nursing homes are on high alert.

Teams of British health officials have even created a vomiting robot to try and understand how to prevent more people from being exposed to the severe projectile vomiting that can occur without warning.

More stories from reporter James Thomas

After that happens, whoever is standing around that person will get the virus.

Professor Ferson says places like cruise ships are the perfect incubators for a pandemic. With thousands of people eating from the same restaurants and breathing the same air, the ship becomes a floating Petri dish.

And when she pulls into a new port, passengers disembark and infect a whole new population.

"It can affect anyone. The people that are particularly vulnerable are the frail elderly, particularly in nursing homes, and very young children may be affected," Professor Ferson said.

"There have been some fatalities linked to this infection, usually in elderly people who have lots of other problems."

Work on a vaccine is underway, but at present none exists and personal hygiene is crucial.

"Anyone with diarrhoea or vomiting needs to be careful about washing hands. Stay away from people ... and try and stay away from work for a day or two after you recover, because we know the virus is still there," Professor Ferson warned.