Four more Marylanders have developed fungal meningitis after receiving a steriod injection for back pain as a national outbreak has grown to 170 victims in several states.

In Maryland, 13 people have been diagnosed with the rare disease and 1,500 could have been exposed to it. One person in the state has died, but health officials have released no specifics about the case.

The outbreak has been linked to the steroid methylprednisolone acetate that was produced and distributed by the New England Compounding Center in Framingham, Mass.

Vials of the steroid were sent to 76 clinics in 23 states, including seven in Maryland. Authorities have said those vials could have been used to inject thousands of patients. People have been infected in 11 states. 

Federal officials continue to investigate and search for the root of the contamination.

Maryland clinics have been calling patients who may have been exposed to the disease and say others will likely develop it in coming weeks.