An ethno-epidemiological model for the study of trends in illicit drug use: reflections on the ‘emergence’ of crack injection Michael C. Clatts *, Dorinda L. Welle, Lloyd A. Goldsamt, Stephen E. Lankenau Institute for International Research on Youth at Risk, National Development and Research Institutes, Inc., 71 West 23rd Street, 4th Floor, New York, NY 10010, USA Abstract Public health, including the prevention of drug use, has long relied upon sentinel marker data obtained from national and regional tracking systems in order to forecast changes in patterns of drug abuse. More recently, these types of data have also played an important role in monitoring particular types of medical consequences associated with drug use, including the spread of HIV, HBV, HCV and other viral infections prevalent in IDU populations. While these types of data may provide an important sources of information about changes in drug use and its consequences, the limits of these sources of data have also become widely apparent. Based on a patchwork of institutionally-derived sources of data (e.g. emergency departments, drug treatment admissions, and law enforcement data on drug seizures and arrests), sentinel marker data typically fail to capture a number of ‘‘hidden populations’’ evidencing ‘‘hidden’’ drug-related risk behaviours. Many of these populations and behavioural practices only become apparent well after they have become diffused across regions and diverse drug user subpopulations, making prevention more difficult and more expensive. Furthermore, these systems cannot capture patterns of episodic use, such as those evidenced in crack injection. Ethnographic methods, including field-based community assessment, semi-structured qualitative interviews, and targeted observation of ‘‘natural’’ venues in which drugs are bought, sold, and used, have the potential to overcome some of the limitations from which ‘‘systems data’’ often suffer. Drawing on an ethno-epidemiological approach, our ongoing multi-site research on the use of injection as a mode of administration in the use of crack cocaine is a case in point, and illustrates the potential utility an ethnographic model for the identification and tracking of emergent and ongoing drug use practices. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Crack cocaine; Ethnography; Drug trends; Injecting drug use; Epidemiology Introduction Sentinel drug forecasting systems often fail to ade- quately identify and assess emerging trends in the use of illegal drugs, with the result that public health systems are rarely able to adequately mobilise local, regional, and national prevention and treatment systems in a timely manner. The spread of crack-cocaine in the USA in the 1980s is a prime example. Drug forecasting systems were slow to identify and track the rapid diffusion of crack smoking and both research and prevention lagged well behind the epidemic. When the epidemic did become apparent, much of the early information came from popular media that provided potent images of unbridled violence and lurid sex, and subsequently, of public health and law enforcement’s alleged control and triumph over the epidemic. In a tragic twist of ‘‘art imitating life’’, much of the research on crack use has reflected similarly erroneous assump- tions about the nature of crack use, often playing upon and reinforcing stereotypical images of one type of user and one type of mode of administration, in an epide- miological trend that had a singular ‘‘start’’ and ‘‘end’’. Despite the propositions made in the USA from sentinel data that the use of crack cocaine is waning, there is potent evidence that it remains prevalent among many groups of drug users, and indeed that both its use and its mode of administration have become more elaborate in the US. As far back as the late 1980s, there has been ample evidence of the emergence of the use of injection as a mode of administration in the use of crack cocaine. Despite its implications for the heightened risk * Corresponding author E-mail address: michael.clatts@ndri.org (M.C. Clatts). International Journal of Drug Policy 13 (2002) 285  /295 www.elsevier.com/locate/drugpo 0955-3959/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0955-3959(02)00123-8