Parents of one of the Hunter's Catholic primary schools were urged to keep their children at home late last week as a significant outbreak of gastroenteritis required the help of Hunter New England Health District's public health unit to contain.
Emails to parents from school principal Duilio Rufo, seen by the Newcastle Herald, note upwards of 180 cases of gastro among students at St Therese's Primary School at New Lambton on Friday, with as many as 22 teachers taking leave because of the outbreak.
On Thursday, the school told parents as many as 89 students were absent and sick and 18 others were sent home after becoming ill at school.
The school has pleaded with parents to keep their children at home if they are unwell as Hunter New England Health was called in to help contain the spread of the infectious bug.
A spokesperson for the health district on Saturday said the matter was under investigation and declined to comment further.
But in a letter to parents, seen by the Herald, the public health unit urged parents to screen their children for symptoms of fever, muscle aches and lethargy before sending them to school and, if they became unwell, to stay at home until 48 hours after symptoms abated.
The health district also advised regular hand-washing as a preventative measure and to discourage children from sharing food with friends at school.
"Gastroenteritis is difficult to control and is easily spread from person to person," the letter said on Friday.
"People are most infectious when they have symptoms but can remain infectious until 48 hours after the last symptom.
"It's important that we use the opportunity the weekend provides us to break the transmission cycles and have the school community return to usual function as soon as possible."
In a statement at the weekend, the Diocese of Maitland-Newcastle confirmed the "highly infectious gastroenteritis outbreak".
"The school notified and has been working with Hunter New England Health since Thursday, August 3, to implement the appropriate control measures, including additional cleaning and hygiene measures," a spokesperson said.
"However, given the highly infectious nature of the virus, the school has experienced a very high number of student and staff absences due to illness.
"All health authority advice and precautionary measures are being followed to ensure the health and safety of the school community."
The school remained open, the statement said, but on advice from the local health authority, people were encouraged to keep children at home if they became ill.
While gastro is not typically serious, it can cause dehydration, and is usually caused by a common virus or bacteria.
It is spread by personal contact with another infected person or a contaminated food, drink or other objects.
It can be treated by drinking fluids to avoid dehydration.
Preventative measures like regular hand-washing with soap can help limit the spread.