NASHVILLE, Tenn. — An outbreak of a rare form of meningitis is likely to grow after sickening 26 people in five states, including four who died, health officials warned.

All received steroid injections, mostly for back pain, a fairly typical treatment. The drug was made by a specialty pharmacy in Massachusetts that issued a recall last week and has shut down operations.

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.