<prompt> A-34 year old person has rapidly developing cough, dyspnoea, expectoration and blood tinged sputum. He is febrile cyanosed and toxic.Chest examination reveals crepitation and rhonchi. The most likely diagnosis is -Legionella pneumoniaPneumonic plagueSepticaemic plaguePulmonary tuberculosis  <response>: Ans. is b i.e., Pneumonic plague . Radidly developing cough, dyspnea, blood tinged sputum with fever and cyanosis is the classical presentation of pneumonic plague. About other options Option a . Legionnaires pneumonia presents as mild cough, only slight production of cough . There is associated diarrhea and neurological abnormalities. . There is no cyanosis Option c Usually in septicemic plague respiratory symptoms do not occur. Option d . Tuberculosis has gradual course. 