I'm yet to wash them in the washer. I usually just rinse them by hand without soap, and just make sure there are no particles in there. Then just lay them out on the rack to dry. I figure they're going to be boiled for an extended period of time, so that'll kill just about anything on there that I can't rinse off.
They seem pretty delicate, so I don't bother adding them to the wash ... but I'm sure yuou probably could and it wouldn't hurt anything.