Infections with Spore-forming Bacteria in Persons Who Inject Drugs, 2000–2009

Norah E. Palmateer

, Vivian D. Hope, Kirsty Roy, Andrea Marongiu, Joanne M. White, Kathie A. Grant, Colin N. Ramsay, David J. Goldberg, and Fortune Ncube

Author affiliations: Author affiliations: Health Protection Scotland, Glasgow, Scotland, UK (N.E. Palmateer, K. Roy, C.N. Ramsay, D.J. Goldberg); Health Protection Agency, London, UK (V.D. Hope, A. Marongiu, J.M. White, K.A. Grant, F. Ncube); London School of Hygiene and Tropical Medicine, London (V.D. Hope)

Abstract

Since 2000 in the United Kingdom, infections caused by spore-forming bacteria have been associated with increasing illness and death among persons who inject drugs (PWID). To assess temporal and geographic trends in these illnesses (botulism, tetanus, Clostridium novyi infection, and anthrax), we compared rates across England and Scotland for 2000–2009. Overall, 295 infections were reported: 1.45 per 1,000 PWID in England and 4.01 per 1,000 PWID in Scotland. The higher rate in Scotland was mainly attributable to C. novyi infection and anthrax; rates of botulism and tetanus were comparable in both countries. The temporal and geographic clustering of cases of C. novyi and anthrax into outbreaks suggests possible contamination of specific heroin batches; in contrast, the more sporadic nature of tetanus and botulism cases suggests that these spores might more commonly exist in the drug supply or local environment although at varying levels. PWID should be advised about treatment programs, injecting hygiene, risks, and vaccinations.

Clostridium and Bacillus spp. produce spores that can be found in soil, dust, human and animal intestines, and aquatic environments; these spores can remain viable for long periods (1). Spores can contaminate illicit drugs or drug-injecting equipment. If injected intravenously, intramuscularly, or subcutaneously, spores can germinate and produce potent neurotoxins or histotoxins that cause illness and death (2). In persons who inject drugs (PWID), these organisms often initially cause localized infections; however, the toxins they produce can result in severe systemic illness, which usually becomes apparent within a week after infection.
Infections with spore-forming bacteria in PWID have historically been more common in the United States than in Europe. By the 1950s, injection drug use accounted for most cases of tetanus in New York (3,4), and wound botulism associated with injecting black tar heroin was first described in California just over 2 decades ago (5). In contrast, such infections have occurred more recently in Europe; in the United Kingdom, for example, few infections had been reported before 2000 (1). Nevertheless, a recent article noted that 367 infections with spore-forming bacteria among PWID in Europe were reported during 2000–2009 (6). Although high rates of these infections were reported in northwestern Europe (United Kingdom, Norway, and Ireland), few cases have been reported elsewhere in Europe. The reasons for this marked regional variation within Europe remain unclear but might reflect drug trafficking routes, the type of drugs injected locally, and/or differences in local injecting practices (6).
In addition to the varied extent of these infections among PWID across Europe, some regional variation within the United Kingdom has been noted (7) but not fully explored. To further explore this variation, we compared the regional rates of infection and death caused by a small number of aerobic and anaerobic spore-forming bacteria among PWID in Scotland and England over a 10-year period beginning in 2000. The availability of detailed epidemiologic data on cases in England and Scotland enabled us to examine regional and temporal trends and demographic patterns. Information about differences in drug-injecting populations and practices that might be associated with infection could be used to prevent future infections.