Nine people who injected the drug were admitted to hospitals in San Diego County with severe myonecrosis between October 2 and November 24, the San Diego County Health and Human Services Agency announced in a news release Wednesday.
The patients ranged in age from 19 to 57 years old, the statement said. Only two survived.
Myonecrosis is a severe soft tissue infection that destroys the muscle. Symptoms often include severe pain near the injection site, swelling, fever, blisters and pale skin that changes to dark red or purple.
Another rare illness associated with black tar heroin injection was reported in San Diego County in October, the statement said. It was the county’s first confirmed case this year of wound botulism — a serious illness that attacks the body’s nerves. Seven cases were reported last year and three in 2017.
Health officials have advised the medical community to be on the lookout for additional cases of severe soft tissue infections linked to heroin use.
“People who use black tar heroin are not only at higher risk of dying from an overdose, but also more prone to developing myonecrosis and wound botulism,” said Dr. Wilma Wooten, a public health officer for San Diego County.
The sources of the black tar heroin are unknown, the statement said, but an investigation is ongoing and additional cases may occur.
CNN’s Christina Walker contributed to this report.