a pox on

Originally an expression of abuse to wish that someone develop pocks, that is to say, contract pox. Though pox can range from smallpox to chickenpox to cowpox to syphilis, this expression almost always referred to the last one, the Great Pox.

a pox on

1. (archaic, offensive) To express curses upon (somebody), when irked or wroth, as though wishing someone "a pox".
   • 1610–1611 (date written), William Shakespeare, “The Tempest”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene i]:

     A pox o' your throat, you bawling, blasphemous, incharitable dog!

2. (humorous, said alternatively with of) To hell with (abstract or unalive things).
   • c. 1595–1596 (date written), William Shakespeare, “Loues Labour’s Lost”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act V, scene ii]:

     A pox of that jest! and I beshrew all shrows.

   • c. 1603–1604 (date written), William Shakespeare, “The Tragedie of Othello, the Moore of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene iii]:

     […] A pox of drowning thyself!

• woe betide, fie upon, to hell with

• “a pox on*”, in OneLook Dictionary Search.