The flu season is in full swing with hundreds of cases being reported at hospitals across Macarthur.
But the flu isn't the only the South Western Sydney Local Health District wants Macarthur residents to keep an eye out for.
The district is urging people to be alert to lesser known signs of meningococcal disease.
Two cases have already been reported in the south-west region this year and the peak period for the disease is still more than a month away.
Public health director Naru Pal said meningococcal disease could occur at any time of year, but cases normally started to increase towards the end of flu season when people's immune systems were weaker from viruses.
"Last year the district reported 12 cases of meningococcal disease," Dr Pal said.
"It is a rare but serious bacterial infection that can cause death within hours so the more symptoms people know about, the better.
"Most cases occur in infants, young children, teenagers and young adults, although people of any age can be affected."
In October last year seven-year-old Marcus Cruz died at Campbelltown Hospital after contracting the disease.
The Narellan Public School student's mum, Evelyn Cruz, told the Advertiser at the time that it was important parents read as much about meningococcal as they could.
"My advice is to be aware of all that is out there," she said.
"This is a parent's worst nightmare and I don't want anyone else to go through this heartache."
NSW Health's director of communicable diseases Dr Vicky Sheppeard said meningococcal could often mimic other common illnesses, so it was important people be aware nearer spring that nausea symptoms, vomiting, neck stiffness, joint pain, light sensitivity or a sudden fever, could be something else.
"Most people normally associate meningococcal disease with a rash of red-purple spots or bruises but in some cases a rash doesn't appear, or it could be the last symptom to take shape," Dr Sheppeard said.
"Meningococcal is spread by secretions from the nose and throat of a person who is carrying the bacteria.
"Close and prolonged contact is needed to pass it on."
Vaccination is the best means of protection against meningococcal disease.
Vaccines for types A, C, W and Y are available on the National Immunisation Program for infants aged 12 months and students in year 10.
Any adolescents aged 15 to 19 years who miss the vaccine in school are eligible for a free vaccine from their GP.
However, as there are several strains of meningococcal disease, and vaccination does not cover all strains, even vaccinated people need to be on the lookout for symptoms.
Parents can find all the information they need to know about meningococcal at www.meningococcal.org.au.