Researchers from the University of California, San Francisco, report that the use of black tar heroin, popular on the West Coast, may be helping to hold down HIV infection rates among injection-drug users who share needles, Reuters Health reports. East Coast cities tend to have illegal supplies of a powdered form of heroin from Asia and South America, but cities west of the Mississippi River tend to have black tar heroin from Mexico. The thicker black tar heroin commonly clogs the needles used to inject the drug, forcing users to regularly clean the syringes and needles, which could be leading to the lower infection rates, according to the researchers. The needles also are discarded more quickly, which also helps prevent their reuse among many heroin users. Black tar heroin also must be heated before use, which may kill HIV in drug paraphernalia, the researchers theorize.
"This paper shows a possible solution for a public health paradox that has been unsolved for 20 years-- i.e., why did Western U.S. heroin injectors not get the full brunt of [the] HIV epidemic?" study coauthor Daniel H. Ciccarone told Reuters Health. Injection-drug users on the East Coast have a far higher HIV prevalence rate than those on the West Coast—more than 40% of New York City users are HIV-positive, compared with about 4% of Los Angeles users.
The full study, titled "Explaining the Geographical Variation of HIV Among Injection Drug Users in the United States," appears in the journal Substance Use and Misuse.