The 1997 case definition appearing on this page was previously published in the 1990 MMWR Recommendations and Reports titled Case Definitions for Public Health Surveillance [MMWR 1990;39(RR13)] (available at http://www.cdc.gov/mmwr/preview/mmwrhtml/00025629.htm). Thus, the 1990 and 1997 versions of the case definition are identical.
Confirmed: a case that is laboratory confirmed