The U.S. government for the first time has quantified the loss of life resulting from a spike in fentanyl use in recent years, stating that 1,013 people died of fentanyl overdoses from April 2005 through March 2007, the Associated Press reported July 24.

Use of an illegal version of the painkilling drug appears to have subsided greatly in the past couple of years, with authorities crediting the May 2006 shutdown of a major fentanyl-making operation in Toluca, Mexico for stemming the outbreak.

Authorities first began to notice an increase in fentanyl overdoses in Chicago in 2005, and by the following year intensified activity was seen in other metropolitan communities across the country as well. Illegally made versions of the drug are sold in powder form and often are mixed with cocaine or heroin, sometimes unbeknownst to users. The narcotic is considered 30 to 50 times more potent than heroin.

Researchers for the Centers for Disease Control and Prevention (CDC) used information such as drugs found at the scene of an overdose to distinguish between deaths from illegally manufactured fentanyl and deaths from misuse of the pharmaceutical product, which are generally indistinguishable in autopsies. Researchers said the overall numbers in the report likely understate the overall problem because they are derived from data from only two states (New Jersey and Delaware) and four cities (Chicago, Detroit, Philadelphia and St. Louis).

The report is published in the July 25 edition of the CDC's Morbidity and Mortality Weekly Report.