Diagnosis of dengue fever.. Decreased number of white blood cells and high albumin rate in urine. Serological diagnosis

1 - decrease in the number of white blood cells within 2 - 5 days of fever to less than half of the normal number.
2. The rate of albumin increases slightly in urine.
3. Serological diagnosis.
4 - injected blood within the first 4 days of fever in the brain of mice or tissue transplantation.