Parents at two Illawarra schools have received a notification from the region's public health unit after confirmed cases of whooping cough in students.
Parents at Lake Illawarra High and Mount Warrigal Public schools have been warned to be alert for signs of the highly infectious disease, also called pertussis.
There's been 3675 cases of whooping cough across the state so far this year according to NSW Health statistics, with 170 of those within the Illawarra Shoalhaven Local Health District.
The region's public health director Curtis Gregory said the public health unit routinely issued letters to parents when cases were reported, to improve awareness and provide information.
He said early diagnosis and treatment of symptoms was important.
"Whooping cough starts like a cold with a blocked or runny nose, sneezing, a mild fever and an occasional cough," Mr Gregory said.
"The cough gets worse and severe bouts of uncontrollable coughing develop. Coughing bouts can be followed by vomiting, choking or taking a big gasping breath which causes a 'whooping' sound.
"The cough can last for many weeks and can be worse at night."
Mr Gregory said some newborns might not cough at all, but stop breathing completely and turn blue. Other babies could have difficulties feeding or they could choke and gag.
Older children and adults might just have a mild cough which can last up to seven weeks, sometimes longer.
"See your GP early and follow their treatment advice; after five days of treatment with appropriate antibiotics people with whooping cough are no longer infectious but without proper treatment they will remain infectious for 21 days," Mr Gregory said.
The spread of whooping cough can be minimised by practicing good personal hygiene and staying away from child care, school and work when sick.
Vaccination was the key to preventing severe whooping cough infection.
"Parents and carers are advised to make sure their children are fully immunised and up to date with their vaccination schedule," Mr Gregory said.
Children can receive catch-up vaccinations from GPs and Aboriginal medical services; while free whooping cough vaccines are available for pregnant women.
"Pregnant women are recommended to be vaccinated at around 28 weeks gestation as this enables whooping cough antibodies to be transferred to the unborn baby," Mr Gregory said.
"This helps prevent severe whooping cough in young babies who are too young to be vaccinated.
"It's also important that all people in contact with newborn babies are up to date with their whooping cough vaccines."