TABLE 1.

Tick-borne diseases discussed in this review

Diseasea	Causative organism	Tick vector(s)	No. of reported casesb	Area(s) of endemicity
Lyme disease	Borrelia burgdorferi	Ixodes scapularis, Ixodes pacificus	36,429/yr	Northeastern and northern Midwest U.S.
B. mayonii	B. mayonii	Ixodes scapularis	NA	Northern Midwest U.S.
B. miyamotoi	B. miyamotoi	Ixodes scapularis, I. pacificus, I. ricinus, I. persulcatus	NA	Northeastern and northern Midwest U.S., California, China, Japan, Russia
Tick-borne encephalitis	Tick-borne encephalitis virus (Flaviviridae: Flavivirus)	Ixodes ricinus, Ixodes persulcatus	>5,000–12,000/yr	Eurasia
Crimean-Congo hemorrhagic fever	Crimean-Congo hemorrhagic fever orthonairovirus (Nairoviridae: Orthonairovirus)	Hyalomma spp., Rhipicephalus sanguineus, among others	>5,000	Africa, Asia, eastern Europe, the Middle East, the Indian subcontinent
HGAc	Anaplasma phagocytophilum	Ixodes scapularis, I. pacificus	4,151/yr	Northeastern U.S.
Babesiosisd	Babesia microti	Ixodes scapularis, Ixodes pacificus	1,910/yr	Northeastern and northern Midwest U.S.
Babesiosis	Babesia venatorum, B. microti, B. divergens	Ixodes ricinus	NA	Europe, northwestern China
HME	Ehrlichia chaffeensis	Amblyomma americanum, Dermacentor variabilis	1,377/yr	Northeastern mid-Atlantic and Midwest U.S.
Severe fever with thrombocytopenia	Severe fever with thrombocytopenia virus (Phenuiviridae: Phlebovirus)	Haemaphysalis longicornis	>650	China, Japan, South Korea
Heartland virus disease	Heartland virus (Phenuiviridae: Phlebovirus)	Amblyomma americanum	40f	Midwest and southern U.S.
E. ewingii infection	E. ewingii	Amblyomma americanum and others	22/yr	Midwest
Powassan encephalitise	Powassan virus lineages 1 and 2 (Flaviviridae: Flavivirus)	Ixodes scapularis, Ixodes cookei	133	Northeastern and northern Midwest U.S.
Bourbon virus disease	Bourbon virus (Orthomyxoviridae: Thogotovirus)	Amblyomma americanum	>5g	Midwest and southern U.S.

^aHGA, human granulocytic anaplasmosis; HME, human monocytic ehrlichiosis.

^bNumbers of cases and geographic locations in the United States are from the CDC (66) unless otherwise noted. NA, data not available.

^cFormerly known as human granulocytic ehrlichiosis (HGE).

^dIncludes cases reported from 24 of 33 states where babesiosis is reportable.

^eAn excellent review of tick-borne viruses in the world can be found in reference 289.

^fNumbers of cases and geographic locations for Heartland virus can be found at https://www.cdc.gov/heartland-virus/statistics/index.html.

^gInformation on Bourbon virus can be found in reference 285.