Fungal meningitis is diagnosed through a lumbar puncture, which draws cerebrospinal fluid from the spine that can be inspected for signs of the disease. Once detected, it can be treated with high doses of intravenous antifungal medications.
"Treatment could be prolonged, possibly on the order of months," said Park, adding that the IV treatment would require a hospital stay.
Unlike bacterial and viral meningitis, fungal meningitis is not transmitted from person to person. Only people who received the steroid injections are thought to be at risk, but only one in 100 of them have developed signs of the disease.
"At the moment the attack rate appears to be one percent or less, but of course more cases are sure to develop," said Schaffner, adding that the level of contamination may have varied from vial to vial. "Some patients also received more than one dose, which would increase their risk."
It's also possible, Schaffner added, that the placement of the needle during the steroid injection could influence the risk.
"Could it be that on occasion the dura -- the outer membrane that covers the brain and spinal cord -- was nicked? That might provide a means of access," he said.