LOS ANGELES (KABC) -- Los Angeles County health officials have issued a warning about black-tar heroin that may be contaminated with a deadly bacteria.County officials are investigating three suspected cases of wound botulism, which can be fatal, associated with heroin use.Sharing needles is also one way the bacteria can spread.Cooking or heating the heroin will not kill the bacteria, officials say.Symptoms of wound botulism can be similar to a drug overdose, including blurred vision, difficulty speaking, swallowing or breathing. Symptoms can appear within days or even weeks of injecting the contaminated drug.San Diego County has also had a recent outbreak of heroin-associated botulism cases.