NASHVILLE, Tenn. (AP) — Health officials are expecting to find more cases of a rare and deadly form of meningitis that has sickened more than two dozen people in five states. Four have died.

All received steroid injections, mostly for back pain, a fairly typical treatment.

The type of meningitis involved is not contagious like the more common forms. This type is caused by a fungus often found in leaf mold and which health officials suspect may have been in the steroid.

Eighteen of the cases are in Tennessee, where a Nashville clinic received the largest shipment of the steroid. The drug was made by a specialty pharmacy in Massachusetts that issued a recall last week. Investigators, though, say they’re still trying to confirm the source of the infection.