"with flu" is a valid phrase that can be used in written English.
An example would be, "Many students have been absent from school this week with flu."
You can't predict with flu.
Elder Daughter is down with flu.
"Aaron arrived with flu," Coleman revealed.
However, he abandoned the race on Friday with flu.
On Sunday van Hanegem was conspicuously absent with "flu".
1994 Judy is off work with flu, leaving Richard to pilot the sofa alone.
Robinson started in place of Quentin Richardson, who sat out with flu-like symptoms.
Mechanical and thermo-gravimetric properties of an unsaturated polyester resin blended with Flu-Gas Desulfurization (FGD) gypsum were assessed.
Then came three months with flu-like symptoms and horrible pains that moved around the body.
In many patients, the CRS is mild and patients present with flu-like symptoms, including fever, myalgia, fatigue, and headache.
His general condition deteriorated 10 days prior to admission, with flu-like symptoms followed by swelling of both legs.
