Two wards are effectively closed to new patients and staff movements are restricted to reduce the risk of spreading the virus.

Mid North Coast Local Health District director of public health Paul Corben said these were standard responses.

The guidelines in action at the hospital include encouraging unwell visitors not to attend the hospital. Regular handwashing is also vital.

Gastroenteritis is commonly caused by viral infections and result in vomiting and diarrhoea.

Mr Corben said they believed the first gastroenteritis case was detected last weekend, and it was not unusual to have people with those symptoms in hospital.

“The public health unit has been aware for a couple of days, and the hospital has been ramping up its responses,” he said.

The best way to reduce your chance of getting viral gastroenteritis is to wash your hands thoroughly with soap and running water for at least 10 seconds before handling and eating food, and always wash your hands after using the toilet.

Outbreaks of gastroenteritis, commonly called the “gastro flu”, increase in winter and are common within families and group settings, such as nursing homes, hospitals, childcare centres and schools.

Doctors and hospitals are required to notify the public health unit whenever there are at least two cases of gastroenteritis that are linked.

Mr Corben said NSW Health had been warning of a gastroenteritis epidemic circulating around the state.

These outbreaks are mostly caused by infection with a virus – most often norovirus or rotavirus – and spread easily.

Mr Corben said people with gastroenteritis should stay at home and keep their fluids up.

Most people recover within 48 hours.