How would the United States goverment handle a major epidemic today?

We already have one. The Obama Plague.

it would quarantine people

Obama would blame the Republicans for resisting Obama care.

The government are usually behind nearly all the major crisis, so believe you me, they are more than ready to take away your rights just like they do after every major crisis.

We would issue a state of emergency...I need to know like what a nuke?
If a nuke went off we would evacuate the area send out a has mat team and save the ones that can be saved. We (we meaning NATO) would launch a full scale invasion on the enemy and there would be a nukular war and it wouldnt turn out good.

It depends on the disease. Most first world countries have stopped vaccinating kids against "old" diseases such as smallpox but third world, developed countries (Mexico, Brazil, Japan, etc) still vaccinate kids against every type of disease possible in case of an epidemic. Well, to answer your question, the U.S. would be in a state of emergency because they barely were able to battle the H1N1 pandemic. Could you imagine an epidemic? No one in their right mind would want to travel to the U.S. risking being infected and Americans would probably not be welcome to travel internationally. It would also devastate border areas along Mexico and Canada.

NOT very Well, -I'm afraid... :(