Almost anything you buy commercially in the Amaryllidaceae family is virused, I would just steer clear unless you get them from trusted friends or other growers. Many Crinum were pass a long plants, especially in the US which almost guarantees virus! While the plants are beautiful a virus can take over your entire collection in one season.
I wish it were possible to eradicate virus and maybe one day it will be, I've seen a guy that is experimenting with heat treatment for extended periods of time, maybe this will bring something to the table that will be realistic for anyone to do!