The site won't let me post a proper link, so you'll have to copy and paste a search from this snippet:
Lyme disease is a stealthy, often misdiagnosed disease that was only recognized about 40 years ago, but new discoveries of ticks fossilized in amber show that the bacteria which cause it may have been lurking around for 15 million years -- long before any humans walked on Earth. The findings were made by researchers who studied 15-20 million-year-old amber from the Dominican Republic that offer the oldest fossil evidence ever found of Borrelia, a type of spirochete-like bacteria that to this day causes Lyme disease.
The original article was found on sciencedaily dot com. Perhaps someone with a longer post history can post the direct link below.