a question: fern virus

[Alfred Geskin]

I have an unknown fern (8 inch dark green wide shiny pinnate leaves on
stalks) and when  I bought it a few fronds had cloudy white spots that I
thought were variagation.  Shortly after I bought the fern, a bird's nest
fern grew a frond with the same spots, which I removed, and since then the
bird's nest fern has been ok, but it made me suspicious of the original
plant's health.  I have since learned that such discoloration can be
produced by viri (viruses).  I cut the affected fronds and all was well for
a month or so, but recently a new frond also had the white spots.

Is this likely to be a virus, and should I discard the two infected plants,
or is removing infected leaves a valid method of control?

-Alfred