A 40 year old male with history of alcohol abuse for 20 years is brought to the hospital emergency with complaints of fearfulness, talking to self, aggressive behavior, tremulousness and saying that there insects crawling under his skin. Physical examination shows tachycardia, palpitations, sweating, and high grade fever. He is unable to recognize few of his family members. There is history of drinking alcohol two days prior to the onset of the present complaints. He is most likely suffering from?