Seven people in San Diego have died in the last two months from a flesh-eating bacteria associated with black-tar heroin use, prompting public health officials to warn the medical community to be on the lookout for additional cases.

The San Diego County Health and Human Services Agency reported Wednesday that the seven people died from myonecrosis, a severe infection that destroys muscle tissue. The dead ranged in age from 19 to 57; five were male.

They were among nine people admitted between Oct. 2 and Nov. 24 to county hospitals with the condition after injecting black-tar heroin, a dark, sticky drug that often contains impurities resulting from crude processing methods.

Two remain hospitalized. One is expected to survive; the other is “quite ill,” said Dr. Eric McDonald, medical director for the epidemiology program at the county health agency.