Cat-scratch disease: an unusual cause of combative behavior. Acute encephalitis is an unusual manifestation of cat-scratch disease. The authors present the case of a 27-year-old man who exhibited the acute onset of encephalitis manifested by violent behavior and confusion. The diagnosis of drug abuse was presumed initially, but a careful examination revealed the true cause to be cat-scratch disease. Emergency physicians are frequently faced with the challenging task of evaluating confused and combative patients. This case demonstrates the importance of a complete physical examination and a thorough laboratory evaluation. 