Norovirus epidemic spreading nationwide

Health experts are warning that norovirus outbreaks are on the increase and are sweeping the country.

The latest case has seen the closure of Nelson College yesterday after about 100 students were suspected to be infected.

Nelson's senior health protection officer Geoff Cameron said, based on the symptoms, it was likely to be norovirus, but this could not be confirmed until lab results were returned next week.

Environmental Science and Research (ESR) communicable disease science leader Gail Greening told NZPA today the instances of norovirus outbreaks had increased over the last few years.

"We had a big year in 2004, a bit like overseas countries had a big year and there were a lot of outbreaks in New Zealand in 2004. Last year was a quieter year, (but) this year it seems to be on the increase again."

Norovirus is found in the faeces and vomit of infected people and people can be infected through direct contact with another person who is sick, through eating contaminated food, or touching surfaces and objects contaminated with the virus.

The symptoms often begin suddenly and include vomiting, diarrhoea and stomach-aches. People may also have a fever, chills, headache and muscle aches.

The illness is usually brief, with symptoms lasting about one or two days. Children tended to have more vomiting than adults.

Dr Greening said she did not know the reason for the increase.

"We have what is called 'global strains' that seem to go from the United States to Europe and they do move around -- and we have very similar strains to Australia.

"But why we have the peaks and drops in prevalence, we're not totally sure why."

Dr Greening said it could be different strains circulating that people have not developed an immunity to.

The higher rate could also be attributed to more instances being recorded due to increased awareness of the disease.

"But I think personally we have seen an increase and there seems to be more outbreaks everywhere."

The virus more often strikes groups of people living in close quarters, she said.

"Like rest homes, hotels and institutions because of the way it (the virus) spreads.

Dr Greening said the virus can survive and stay infectious on surfaces for several weeks.

"Once there is an outbreak around you get this epidemic spread from people secondary spreading it (the virus) from person to person as well as the initial case, which could be from eating contaminated food."

Dr Greening said the best way to avoid becoming ill from the norovirus was simply "very good personal hygiene".

"And if you are sick, keeping away from other people and not going and coughing and vomiting over people."

She said if places like boarding schools or hospitals experience an outbreak, they have to be closed down.

"Because it has to be a quarantine situation to clean everything down and keep infected people away from others so they don't spread it."

She said that in elderly or vulnerable people, the virus can be deadly.

"In some cases it can be the last straw because it's just so traumatic on the body."

- NZPA