Drugs of abuse and infectious diseases.

The association of increased severity of infectious diseases and recreational drug abuse can be traced to the last century with the finding that alcoholics often suffered more severely from bacterial pneumonia than nonalcoholics. More recently there have been numerous associations with use of opiate and other psychogenic drugs and increased incidence and severity of a variety of infectious diseases including the human immunodeficiency virus and development of AIDS. In fact, the AIDS epidemic has heightened awareness of the importance of abused drugs as cofactors in disease precipitation and severity. Evidence is examined for the role of opiates, marijuana, and alcohol as substances that promote infectious diseases.