Agreed.
Unless your condition is preventing you from walking, you should go to the gym.
Ofcourse, a high fever is not normal and should be looked at by a doctor if it persists.
Working out will make sure nutrients are being pumped in all parts of your body, it might even help to get better.
Especially when on medication (like antibiotics

) you _could_ see some negative effect on your performance, although from personal experience I must say it mostly effects your perceived energy level.
Once the iron is on your back it is only you and your mental state which will determine if you are going to make it or not (especially if the weights are relatively low) so do not let being sick be an excuse to fail !