Picture background in PDF conversion

[Dea Syria]

My boss wanted me to create a word document that would look like parchment. He supplied a jpeg of a scan of a sheet of parchment. I inserted it as a background using the fill effects that's under the page color section on the page layout tab (this is in windows 2007 running on Vista).



Everything was fine, but now he wants it turned into a PDF. But when I save the word file as a PDF, there is no longer a single parchment image filling the page, but rather the image is used as a tile repeated a couple dozen times to fill up the background with small copies of the jpg image (I guess its like a texture, but it was never a texture in the word file).

What do I have to do to get the picture to display as a single background image per page in the PDF?

By the way, I tried a new file with a different image, just as a test, and the result was the same: in the world file, one large background image per page, in the PDF file dozens of little background images per page.

Thanks for any help.