NASHVILLE, Tenn. – An outbreak of a rare and deadly form of meningitis has now sickened 26 people in five states who received steroid injections mostly for back pain, health officials said Wednesday. Four people have died, and more cases are expected.

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

Three cases have been reported in Virginia, two in Maryland, two in Florida and one in North Carolina. Two of the deaths were in Tennessee; Virginia and Maryland had one each, the Centers for Disease Control and Prevention.