Analysis of data obtained from discrete variables requires the use of specific statistical tests which are different from those used to assess continuous variables (such as cardiac output, blood pressure, or PaO 2) which can assume an infinite range of values.
Primary symptoms of dengue appear three to 15 days after the mosquito bite and include the following: 1  high fever and severe headache, 2  with severe pain behind the eyes that is apparent when trying to move the eyes.
Initial symptoms of yellow fever include sudden onset of fever, chills, severe headache, back pain, general body aches, nausea and vomiting, fatigue, and weakness.Most people improve after these initial symptoms.ellow fever virus is found in tropical and subtropical areas in South America and Africa. Yellow fever virus is a very rare cause of illness in U.S. travelers to these areas.