Update: Clostridium novyi and unexplained illness among injecting-drug users--Scotland, Ireland, and England, April-June 2000.

Since April 19, 2000, health authorities in Scotland, Ireland, England, and the United States have been investigating an outbreak of unexplained illness and death among injecting-drug users (IDUs) in the United Kingdom and Ireland (1-3). Initial testing of specimens from 76 IDUs identified Clostridium species in 18 (24%) patients; nine were Clostridium novyi. This report updates the investigation of this outbreak, which indicates that Clostridium species may be associated with these illnesses.