Evolution of a laboratory based system for investigating outbreaks of infectious intestinal disease.

In 1995 Preston Public Health Laboratory introduced an incident logging system intended to improve the investigation of suspected outbreaks of infectious intestinal disease. A unique incident log (Ilog) number assigned and issued to the reporting individual and other interested parties when the laboratory is informed of a potential outbreak is used to identify all associated specimens submitted to the laboratory and is quoted in all communications about the incident. The results are reviewed formally each month. Between January 1995 and December 1998, 349 potential outbreaks of infectious intestinal disease were investigated, 325 of which were considered to be general outbreaks. Small round structured viruses were identified in 45% of these outbreaks, salmonellas in 8%, and no pathogens in 35%. Data from the national surveillance scheme for general outbreaks of infectious intestinal disease included 104 general outbreaks in 1996 and 1997 for the entire North West region, but our laboratory alone reported 184 general outbreaks during that period. The Ilog system is a simple and effective means for reviewing data from outbreaks, and helps to coordinate their investigation.