The Centers for Disease Control in Atlanta said the number of cases had risen to 64, up from 47 cases and five deaths in seven states a day earlier. Tennessee had the most cases -- 29 -- followed by Virginia (11), Michigan (8), Indiana (5), Florida (4), Maryland (3), North Carolina (2), Minnesota (1) and Ohio (1).
The source of the outbreak of the non-contagious inflammation of the brain's lining had yet to be confirmed, officials at the CDC said, though interim data indicated all infected patients received injections of preservative-free methylprednisolone acetate prepared by New England Compounding Center in Framingham, Mass.
The CDC said several of the afflicted patients had received steroid injections into the spine, and several suffered strokes related to the meningitis.
"The source of the fungus has not yet been identified, and the cause of infections in the other patients is still being assessed," the CDC said on its website.
"At this point, there is not enough evidence to determine the original source of the outbreak; however, there is a link to an injectable steroid medication. The lots of medication that were given to patients have been recalled by the manufacturer."
The states that received the implicated product are: California, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Maryland, Michigan, Minnesota, North Carolina, New Hampshire, New Jersey, Nevada, New York, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Virginia and West Virginia.
"Epidural injections are generally very safe procedures, and complications are rare. Fungal meningitis is an extremely rare cause of meningitis overall, including after epidural injections," the CDC said. "The type of epidural medication given to patients affected by this outbreak is not the same type of medication as that given to women during childbirth."
Fungal meningitis occurs when the protective membranes that cover the brain and spinal cord are infected with a fungus. Fungal meningitis can develop after a fungus spreads through the bloodstream from somewhere else in the body, as a result of the fungus being introduced directly into the central nervous system, or by direct extension from an infected body site next to the central nervous system, the CDC said.