Spruce losing needles

[s003apr]

I have a spruce that lost needles on its lower half on the eastern facing side.
[img]https://img30.imageshack.us/img30/9877/spruce.jpg[/img]
I see no other signs of infestations or fungus or anything like that and there are two other spruces close by that are not having any issues.

What are the likely causes of this and is there anything that I can do to help the tree recover?

[bullthistle]

I'd check with copperative extension and see if there are probelsm with spruce in your area. I doubt you can save the one that already shed its needles.