A substance used to deworm livestock has made its way into the local cocaine supply, sickening 10 people in the last five months. According to King County health officials, 10 men and women—all primarily in their 40s and 50s—have been admitted to local hospitals a total of 13 times after they used cocaine possibly tainted with the drug levamisole.

King County Public Health disease-control officer Dr. Bob Wood says health officials don't yet know why the cocaine supply has increasingly become tainted with levamisole. Wood says it's possible the drug is being used to bulk up cocaine during production, and he says there has also been some speculation that the deworming agent "might add to the euphoria people get when they take cocaine." The problem is that levamisole also drops users' white-blood-cell count to zero—essentially causing drug-induced AIDS—making them susceptible to serious bacterial infections. So far, three deaths (in Spokane, New Mexico, and Alberta, Canada) have been linked to levamisole-tainted cocaine.

Levamisole only stays in the system for five and a half hours, Dr. Wood says, but that's long enough for the drug to shut down white-blood-cell production and expose users to infection. Antibiotics are used to treat the infections, and doctors have used a drug called Neupogen to jump-start bone marrow into resuming production of white blood cells.

As of late last year, "nearly a third of all cocaine seized in the U.S. is tainted with the drug," the Associated Press reported on August 31, based on a review of Drug Enforcement Administration documents. King County received two reports of sickness in June, six in July, and two in August—the latest case on August 20. Nine of the 10 cases countywide were reported in Seattle, one was found in Shoreline. According to Wood, people who snort, inject, smoke, or "keister" cocaine are susceptible to exposure to levamisole—which is colorless, odorless, and can't be detected except through laboratory testing.

On top of the lack of information about why bad cocaine is entering the market, health officials also aren't sure where it's coming from. As Wood says, the health department is limited in its investigatory powers. "When you get involved in asking questions about who [their] supplier was, that's something that the health department stays away from," Wood says.