Until now, the only ticks known to spread Rocky Mountain spotted fever were the less common American dog tick and the Rocky Mountain wood tick.  The Common dog tick was recently linked to a serious outbreak of the disease in Arizona.   The newly implicated tick lives everywhere in the world and there is some concern that there may be larger outbreaks of the disease.  See the links below for more information.

http://www.cnn.com/2005/HEALTH/08/10/dog.tick.disease.ap/index.html

http://content.nejm.org/cgi/content/short/353/6/587