1) Fever is the most common symptom of an infectious disease. It can be a high temperature for several days without characteristic symptoms of acute respiratory infections, or, conversely, a low (subfebrile) temperature for a long time (2 weeks or more) without a specific reason. 2) Discoloration of the skin and sclera of the eyes (jaundice), discoloration of urine and stools. 3) The appearance of a rash of any nature, especially against the background of a rise in temperature. 4) Allergic manifestations are long-term and without much success after treatment with an allergist. 5) Stool disorders of a different nature (from frequent for a short period of time to semi-liquid for 2 or more weeks). 6) Nonspecific symptoms: weakness, fatigue, headaches, muscle weakness and others. 7) Any symptoms after a characteristic epidemiological history (contact with a sick person, bites of insects, rodents, contact with sick cattle, other animals and birds, leaving the country with a visit to any countries with a subtropical and tropical climate).