A 25-year-old patient was delivered to an infectious diseases unit on the 3rd day of illness with complaints of headache, pain in the lumbar spine and gastrocnemius muscles, high fever, chills. Objectively: condition is of moderate severity. Scleras are icteric. Pharynx is hyperemic. Tongue is dry with dry brown coating. Abdomen is distended. Liver is enlarged by 2 cm. Spleen is not enlarged. Palpation of muscles, especially gastrocnemius muscles, is painful. Urine is dark in color. Feces are normal in color. What is the most likely diagnosis?