That is one ugly virused plant.
If it were me, I would dig it all out after you have enjoyed the blooms of the healthy ones. I wouldn't be worried about the virus spreading through the soil, unless you originally planted them rather close together (less than 2 inches between), in -+++which case they could grow enough to touch or be too close for comfort that when you dig they might rub each other.
My concern stems from what might happen with this current year's growth of the virused bulb. If you didn't get all of the stem, it could produce stem bulblets, and the resulting baby plant it produces next season might be undetectable among healthy bulblet growth. There is also the possibility of the virus causing the bulb to "fracture" into many small bulbs, producing another delemma for separation this fall or next season.
Rather than trying to surgically remove the bulb without disturbing the others, that's way too much work for me, and I would opt for the easy way:
dig up all three bulbs with one big shovel, and gently separate the bad bulb. Use one hand for the virused bulb, one hand for the good bulbs so there is no possibility of transmitting the virus yourself.
Rick
