Attached is a photo of a skin reaction to crack cocaine that has been contamined with a deworming medication used on livestock. Handout

Crack cocaine contaminated with a deworming agent used in livestock is causing a severe skin reaction in those who smoke or snort the drug, researchers are finding.

Physicians in emergency departments in both Los Angeles and New York are seeing deep, purple colored patches and decomposing skin on ears, noses, cheeks, and other parts of the body on some crack cocaine users, according to findings in a report published in the Journal of the American Academy of Dermatology.

The skin lesions can be painful and horrific and point to a potential public health epidemic, researchers say.

The report, which was written six months ago, tracked six patients with similar skin reactions. All were cocaine users.

After some follow ups, researchers found that patients who used the contaminated cocaine all had traces of the deworming agent levamisole in their bodies. Levamisole was once used in humans to kill intestinal worms but was discontinued because of allergic reactions. The agent is now used on cows, pigs, and sheep.

Such severe skin reaction cases appear to be continuous in Los Angeles, said Dr. Noah Craft, a researcher at the Los Biomedical Research Institute at Harbor-UCLA Medical Center and principal author of the report.

"We see them regularly," Craft said. "We believe

In one case, a patient used cocaine again and developed the same skin reaction again.

"He then switched drug dealers and the problem cleared up," Craft said.

Cocaine use has dropped in the United States, from 2.1 million in 2007 to 1.7 million in 2009, according to national drug agencies, but nearly 70 percent of all cocaine samples in the United States and Canada contain levamisole, according to published reports.

The federal Drug Enforcement Administration typically collects the drug, but doesn't test it regularly. However, of the cocaine that is analyzed, levamisole appears frequently, said Sarah Pullen, spokeswoman for the DEA.

"The cocaine is cut here by lower level drug dealers," said Pullen said. "It's a good cutting agent for crack. The appeal is that it makes nice size rocks."

Hospitals contacted in the San Fernando Valley did not report seeing such cases, but Craft said it may be because physicians are mistaking the marks for an autoimmune disease.

The contaminated cocaine also can cause life-threatening immune-system disorder called agranulocytosis, which kills 7 to 10 percent of patients who contract it, Craft said.

Craft said he sees at least one patient a month with the skin reaction at Harbor UCLA Medical Center.

"The patients are really frightened," Craft said. "Sometimes it's quite painful. The skin is dying."

Craft said the report was published specifically to educate the public of the additional risks of cocaine use and to raise an awareness among physicians who see the skin reactions.

"We want to educate the public," he said. "It doesn't seem like they need another reason to stay away from cocaine, but this would be one more reason not to use it. It does definitely frighten people more."