Patches on Catt leaves
 

Is this a virus?

It doesn't look good. Maybe its a fungus though, I'm definitely not an expert but I would treat it as a fungus and see if it gets better, if not, you might want to test it for a virus.

Isolate the orchid until you know what is wrong. Hope these will help:
Orchid Pests, Orchid Diseases
http://www.houstonorchidsociety.org/...ySueBottom.pdf

http://www.icogo.org/images/Dr._Chin...id_Viruses.pdf
Orchid Virus

Hi why_le. I am also having trouble with my cattleya. Like others, I recommend isolating it from other orchids.I am beginning to learn about keeping orchids and a book that has helped me a lot in identifying fungal, bacterial, and viral issues is published by the American Orchid Society. It's called "Orchid Pests and Diseases." It has detailed description on identifying the problem and recommended treatment.
I bought it at a local orchid society meeting, for twelve dollars.

Ok..... Shall I destroy it?

I usually just put them in a seperate room and then take care to practice good hygene so nothing might spread to the others. If the orchid shows new symptoms and seems to lack vigor, I will then toss it. However, with these spots, I would probably toss it right away. It could be a fungus, sure, but I probably would be relieved that it was gone.