Models of a heroin epidemic.

Heroin addiction may be considered an epidemic disease that is communicated by people who are addicted to the drug. It has been suggested that the most recent epidemic in the United States had its peak incidence in 1969. The age of heroin addicts entering treatment has increased systematically from 1973 to 1976 at a rate of less than one year of age per calendar year. This pattern is consistent with a moderate decline in a national heroin epidemic or a geographical migration of the epidemic from more to less populated areas. There are also seasonal trends in the age of admission to treatment.