The Law governing the INTERSTATE transport of disease is a function of FEDERAL authorities.

Who Is in Charge (click here)

The federal government

• Acts to prevent the entry of communicable diseases into the United States. Quarantine and isolation may be used at U.S. ports of entry.
• Is authorized to take measures to prevent the spread of communicable diseases between states.
• May accept state and local assistance in enforcing federal quarantine.
• May assist state and local authorities in preventing the spread of communicable diseases.

State, local, and tribal authorities

• Enforce isolation and quarantine within their borders.

It is possible for federal, state, local, and tribal health authorities to have and use all at the same time separate but coexisting legal quarantine power in certain events. In the event of a conflict, federal law is supreme.

§264. Regulations to control communicable diseases (click here)

(a) Promulgation and enforcement by Surgeon General

The Surgeon General, with the approval of the Secretary (The secretary referred to is the HHS Secretary) , is authorized to make and enforce such regulations as in his judgment are necessary to prevent the introduction, transmission, or spread of communicable diseases from foreign countries into the States or possessions, or from one State or possession into any other State or possession. For purposes of carrying out and enforcing such regulations, the Surgeon General may provide for such inspection, fumigation, disinfection, sanitation, pest extermination, destruction of animals or articles found to be so infected or contaminated as to be sources of dangerous infection to human beings, and other measures, as in his judgment may be necessary.

42 U.S.C. 
United States Code, 2011 Edition
Title 42 - THE PUBLIC HEALTH AND WELFARE
CHAPTER 6A - PUBLIC HEALTH SERVICE
SUBCHAPTER II - GENERAL POWERS AND DUTIES
Part G - Quarantine and Inspection
From the U.S. Government Printing Office