South and North Tamworth Cricket Clubs attended an event on Saturday night, player Harry Baxter had two beers about 7pm.

By Sunday evening, he became seriously unwell.

"It hit me like a freight train," Mr Baxter said.

"From our club alone there was at least 25, 26 people who got sick.

"I'm still not 100 per cent, I'm not going anywhere put it that way."

The incident has been reported to NSW Health after a number of people presented at the hospital for treatment.

Public health expert Dr David Durrheim said the outbreak is being investigated, and those with symptoms are being surveyed.

"We are working with the NSW Food Authority and the council. It was a catered event so we are obliged to investigate it," he said.

"It's most likely Norovirus but we can't be sure without laboratory evidence."

The symptoms of the viral infection are vomiting, loose or watery diarrhea, nausea, fever, headaches and muscle aches.

There is a risk that people with the infection can become dehydrated, so Dr Durrheim recommends people keep their fluids up and avoid contact with others.

"If it is Norovirus, that can be spread between people's hands with poor hygiene, contaminated objects, food or drink," he said.

"It's that infectious that you don't need to be exposed to a large quantity to get the virus. If someone vomits in a confined space the bug can be breathed in through the air.

"Symptoms will usually start within 48 hours after the person has been exposed."

In Tamworth, there's often a period at the tail end of winter where reports of Norovirus increase.

Patients can remain infectious for 48 hours after their symptoms stop, so people who have been infected should avoid public places, swimming in public pools and food preparation.

A surveillance system at Tamworth hospital was triggered overnight that showed more cases than normal had presented, Dr Durrheim said.

"We usually have five present in ED at this time, this was three times that with 17 people," he said.

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"We are aware there was already gastro in the community before the event so Tamworth is experiencing an increase but it's usually fairly short-lived.

"It's self-curing most of the time, there isn't really an antiviral or antibiotic you can take - it's important those with symptoms rest and are well-hydrated."

Specimens have been taken from those infected at the social event to determine the specific cause and whether there is an ongoing health risk.

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