Explanation:

Dengue High Fever (DHF) is characterized by a fever that lasts for 2 to 7 days, with general signs and symptoms consistent with dengue fever. In addition to these symptoms, if a patient suspected with dengue experiences decrease in platelets or an increase in blood haematocrit, it becomes more certain that the patient is suffering from the infection.Platelets are cells in blood that help to stop bleeding, while haematocrit indicates thickness of blood. The smallest blood vessels become excessively permeable allowing fluid component to escape from blood vessels to organs of the body. This may lead to failure of circulatory system, which might also cause death.