Another case of invasive meningococcal disease has been identified in Adelaide, the second in 24 hours.
Health officials say a 29-year-old woman has been admitted to hospital in a stable condition.
Her case follows that of a two-year-old boy who remains in a serious but improving condition after being confirmed to have contracted the B strain of the disease.
Chief Medical Officer Paddy Phillips says the two cases are not related.
They take the number reported in SA so far this year to 24, including 19 cases of the B strain compared to 31 cases at the same time last year.
Professor Phillips has defended SA Health's handling of the case of the young boy amid concerns some parents with children at the childcare centre he had been attending were not properly notified.
He has also defended the decision not to publicly name the centre.
"It's always a fine balance between informing the public and causing anxiety and stigma among those affected," he said on Thursday.
"With meningococcal disease, the risk to the community from this child is zero; the risk to the contacts in the childcare centre is low but real.
"That's why we go out and provide clearance antibiotics to those who have been in close contact with the affected cases."
Prof Phillips said in the boy's case, 64 people were being provided precautionary treatment.
"Our duty of care is to those directly affected by any public health risk and there was no public health risk to the rest of the community from this case," he said.
The boy's case also came after Monday's start to free vaccines in SA for the B strain of the disease for children between six months and four years.
It was not known if he had been vaccinated.
