Unusual Illness

In the context of bioterrorism agents, an unusual illness is one in which patients present with signs and symptoms that don’t fit a recognisable clinical picture; or which is of known aetiology, but usually not expected to occur in the place where it is identified; or which is of known aetiology, but behaves in an atypical manner (e.g., doesn’t respond to the usual therapy); or is of unknown aetiology