By Rachael Rettner - Senior Writer  -  Live Science

Seven people in San Diego have died in recent months from a "flesh eating" infection tied to use of black tar heroin, according to health officials.

On Wednesday (Dec. 4), the San Diego County Health and Human Services Agency announced that nine people in the area had been hospitalized with a serious infection called myonecrosis over a two-month period (from Oct. 2 to Nov. 24). Of these, seven died. The patients ranged in age from 19 to 57 years, and all had used black tar heroin, according to a statement from the agency.

Myonecrosis is a rare bacterial infection that destroys muscle tissue, the statement said. Often, it is caused by a type of bacteria called Clostridium, which releases a toxin that causes tissue death, according to Healthline. These bacteria also release a gas, and the condition is sometimes referred to as "gas gangrene." 

People who inject illicit drugs, especially black tar heroin, are at higher risk of developing myonecrosis, the statement said.

The condition can spread quickly in the body, and lead to amputations or death, according to the statement. Symptoms often include severe pain around a wound or injection site, swelling, blisters with foul-smelling discharge and skin that turns gray, dark red, purple or black.

A different infection called wound botulism, which attacks the body's nerves, is also linked with black tar heroin use. In October, there was also one case of wound botulism reported in San Diego, which was the first reported case in the area in 2019, the statement said.

The sources of black tar heroin in both the myonecrosis and wound botulism cases are unknown, the statement said. An investigation in ongoing, and additional cases may be reported.