When a player draws the first Virulent Strain Epidemic card, the Virulent Strain is determined for the rest of the game. After Performing this card's Infect step, the disease with the most cubes on the board is the Virulent Strain.
If several diseases are tied for the most cubes on the board, the Virulent Strain is chosen randomly among the tied diseases.
Once the Virulent Strain is chosen, special cubes are used to distinguish it from normal diseases.
