Disease		Causative agents	Vectors	Geographic regions
Rocky Mountain spotted fever		Rickettsia rickettsii	Wood tick (Dermacentor andersoni)	Limited to Western hemisphere; all states except Maine, Hawaii, and Alaska
			Dog tick (Dermacentor variabilis)	Common to eastern and southern states
Lyme disease		Borrelia burgdorferi	Black-legged or deer tick (Ixodes scapularis)	Majority of cases are reported in the Northeast and Great Lakes area; reported in every state except Montana
			Main reservoir: white-footed mouse
Ehrlichiosis
	Human monocytic ehrlichiosis	Ehrlichia chaffeensis	Lone Star tick (Amblyomma americanum)	South-central United States
			Dog tick (D. variabilis)	Southeastern United States
	Human granulocytic ehrlichiosis	Anaplasma phagocytophilum	Black-legged or deer tick (I. scapularis)	Upper midwestern and northeastern United States
Tularemia		Francisella tularensis	Lone Star tick (A. americanum)	Occurs in rural areas in all states except Hawaii, mostly in south-central and southeastern United States
			Wood tick (D. andersoni)	Western United States
			Dog tick (D. variabilis)	Southeastern United States
Babesiosis		Babesia microti	Black-legged or deer tick (I. scapularis)	Most cases occur in the northeasternUnited States.
		Babesia divergens
Colorado tick fever		RNA orbivirus	Wood tick (D. andersoni)	Found predominantly in Rocky Mountain region
Relapsing fever		Spirochete withinBorrelia genus	Ticks of the Ornithodoros genus	Most cases occur west of the MississippiRiver, especially in mountainous areas.
			Main reservoirs: rodents, rabbits, and hares