The patient was taken to the department in serious condition: body temperature - 36.5°C, inhibited, facial features are pointed, the tongue is dry, the skin fold is not straightened. Tachypnea up to 28/min., Pulse - 126/min., AT - 60/40 mm Hg. art., the abdomen is painless. During hospitalization was observed: vomiting fountain, watery stools resembling rice broth. From the epidemiology it is known: a week ago he returned from Sudan (Africa). Choose a starting therapy for emergency care: