A Sydney school has been offered antibiotics as a preventive measure following an outbreak of meningococcal disease late last month.
NSW Health issued a public health alert about two weeks ago after two cases of meningococcal were recorded in Sydney's northern beaches region.
A third case was detected on June 1.
Close contacts were identified and offered preventive antibiotics.
"The crucial action people can take is to get assessed quickly by their local doctor or emergency department, as early recognition and treatment is very effective," Northern Sydney Local Health District public health director Dr Michael Staff said.