Does a player need to complete a full turn (i.e. 4 actions, pickup, infect) if during the action portion the final disease was cured? I only ask because there was only 1 player card left in the deck and I wouldn't have been able to complete a full turn, which in the rules, signifies that players have lost. However, I knew that I could cure the final disease in one action.
You won. The rules state that in order to win, you must discover the cure to all 4 diseases. The moment you discover the 4th cure, the game ends and you win.
From the rules:
The players win as soon as cures to all 4 diseases are discovered.
The players do not have to eradicate all 4 diseases to win; just cure them. Once all diseases are cured, the game ends and players win immediately, no matter how many cubes are on the board.
You can look at it another way. If you did not lose, then you must have won. What is one way to lose? You lose if you cannot take two cards at the end of your turn, so you have four actions to win. From 2013 edition:
The game ends...if a player cannot draw 2 Player cards after doing his action