Characteristics
Human flu symptoms usually include fever, cough, sore throat, muscle aches, conjunctivitis and, in severe cases, severe breathing problems and pneumonia that may be fatal. The severity of the infection will depend to a large part on the state of the infected person's immune system and if the victim has been exposed to the strain before, and is therefore partially immune.
All of these symptoms are characteristic of numerous infectious agents, so many that most diagnoses of human influenza technically are diagnoses of influenza-like illness (ILI) and most cases of ILI are not due to influenza.
Read more about this topic: Human Flu