What is it and how to stop this disease?

[greenpassion]

Hello all. Haven't been on here for quite some time. In the past year I have rehomed 80% of my orchids. I do have nine left and of the nine there is a disease spreading rather rapidly through the collection. Hopefully these pictures will post and I will get some responses. They are in orchidia in an East window. They bloom reliably and other than these leaves with these pitted Brown markings, they all appear to be in good health. Help!