WOUND BOTULISM ASSOCIATED WITH BLACK TAR HEROIN AMONG INJECTING DRUG-USERS

Context.-Wound botulism (WB) is a potentially lethal, descending, flac cid, paralysis that results when spores of Clostridium botulinum germi nate in a wound and elaborate neurotoxin. Since 1988, California has e xperienced a dramatic increase in WB associated with injecting ''black tar'' heroin (BTH), a dark, tarry form of the drug. Objective.-To ide ntify risk factors for WB among injecting drug users (IDUs). Design.-C ase-control study based on data from in-person and telephone interview s. Participants.-Case patients (n=26) were IDUs who developed WB from January 1994 through February 1996. Controls (n=110) were IDUs newly e nrolled in methadone detoxification programs in 4 counties. Main Outco me Measures.-Factors associated with the development of WB. Results.-A mong the 26 patients, the median age was 41.5 years, 15 (58%) were wom en, 14 (54%) were non-Hispanic white, 11 (42%) were Hispanic, and none were positive for the human immunodeficiency virus. Nearly all partic ipants (96% of patients and 97% of controls) injected BTH, and the mea n cumulative dose of BTH used per month was similar for patients and c ontrols (27 g and 31 g, respectively; P=.6). Patients were more likely than controls to inject drugs subcutaneously or intramuscularly (92% vs 44%, P<.001) and used this route of drug administration more times per month (mean, 67 vs 24, P<.001), with a greater cumulative monthly dose of BTH (22.3 g vs 6.3 g, P<.001). A dose-response relationship wa s observed between the monthly cumulative dose of BTH injected subcuta neously or intramuscularly and the development of WB (chi(2) for linea r trend, 26.5; P<.001). In the final regression model, subcutaneous or intramuscular injection of BTH was the only behavior associated with WB among IDUs (odds ratio, 13.7; 95% confidence interval, 3.0-63.0). T he risk for development of WB was not affected by cleaning the skin, c leaning injection paraphernalia, or sharing needles. Conclusions.-Inje ction of BTH intramuscularly or subcutaneously is the primary risk fac tor for the development of WB. Physicians in the western United States , where BTH is widely used, should be aware of the potential for WB to occur among IDUs.