For the love of God, people, it's "flu symptoms," not "flu-like symptoms." Let me walk you through it. There is a difference between having a particular illness, such as influenza, and having symptoms of that illness. Symptoms are signs, indicators, or manifestations. Flu symptoms include nausea, vomiting, fever, cough, runny nose, and muscle aches. Doctors make diagnoses based on symptoms. Having flu symptoms does not mean that one has the flu; it merely points in that direction. Two or more illnesses can have the same, or roughly the same, symptoms.
Still with me? If you come down with a fever, experience nausea, begin vomiting, and start coughing, you have flu symptoms. This does not mean you have the flu; it means you have symptoms of flu. You might have something other than the flu. What sense could it make to describe what you have as "flu-like symptoms"? That you have signs that are like signs of the flu? But that's not true! You have signs of the flu. You have flu symptoms. Whether you have the flu is a separate question.
I think the source of this mistake is that people don't know what symptoms are. (Not knowing what symptoms are is symptomatic of a bad education.) They think every illness has a unique set of symptoms. Flu (they think) has its own symptoms and no other illness has those same symptoms. But this is false. As I said, two or more illnesses can have the same symptoms. A symptom is a sign or indicator of something. It is not the thing itself.
Flu symptoms, people. Flu symptoms. To repeat: You can have flu symptoms even if you don't have the flu. For the love of God.
Keith Burgess-Jackson, J.D., Ph.D. 