Ticks carry bacteria that can cause human disease. Ehrlichiosis, Rocky Mountain spotted fever, and Lyme disease are infectious
diseases transmitted by tick bites. The Lone Star tick carries Ehrlichia chaffeensis (named to honor bacteriologist Paul Ehrlich),
the bacteria that causes human monocytic ehrlichiosis.
Another type of tick, the deer tick, carries the bacteria responsible for
another type of ehrlichiosis, called human granulocytic
ehrlichiosis. Deer ticks also carry the organism that causes Lyme disease.
The November 10, 2004, issue of JAMA includes an
article about ehrlichiosis.