A) Nobody likes to be sick - and a flu is a pretty nasty sickness with all the vomiting and pain.

B) If you do not at least try to contain it, it will spread faster, and perhaps hit more of the people actually in danger from it.

C) If I were your employer and found out you had gone to work knowing you had an illness like this, you'd be fired as it is bad for business.

Also, regarding the flu... it is a general flu thing, so the symptoms may vary according to who has it... but in general most of the symptoms you have are included.