Like all ticks in the genus Ixodes, the deer tick or I. scapularis is a three host tick. Each feeding stage (larva, nymph and adult) requires one vertebrate blood meal for its development. The life cycle of I. scapularis may range from two to four years and appears to be regulated by host abundance and physiological mechanisms of the tick. The nymphal stage is most responsible for disease transmission to humans.
Four diseases are spread by the bite of I. scapularis, the deer tick: Lyme disease, caused by Borrelia burgdorferi; human babesiosis, caused by a protozoan, Babesia microti; human granulocytic ehrlichiosis (HGE) (a bacterial infection); and tick-borne encephalitis (TBE) (a viral infection).