Influenza
An acute, contagious respiratory infection that is characterized by sudden onset, high fever, chills, headache, muscle soreness, and sometimes prostration. Nasal discharge, cough and sore throat are also common; and stomach symptoms such as nausea, vomiting and diarrhea may also occur, but are more often seen in children than adults. Most people recover from the flu in a few days to less than two weeks. People age 65 years and older, people of any age with chronic medical conditions (such as asthma, diabetes, or heart disease), pregnant women, and young children are more likely to get complications from influenza.