Among all tick species worldwide, only a small number transmit viruses, bacteria, or parasites (collectively known as pathogens) that infect humans. Different tick species carry different pathogens. Adult ticks are most easily identifiable, although male and female ticks of the same species differ. The nymphal and larval ticks are the most difficult to identify, as they’re very small.
American Dog Tick
Distribution:Dermacentor variabilis is popular east of the Rocky Mountains and only in small numbers along the Pacific Coast. The newly identified species, Dermacentor similis, occurs west of the Rocky Mountains. We still need to learn more about how these species transmit diseases. Diseases Transmitted: Tularemia and Rocky Mountain spotted fever. Remarks: Bite risks peak during the spring and summer, with adult females most likely to attack people.
Blacklegged Tick
Distribution: The United States, particularly the eastern region, is home to Ixodes scapularis. Diseases Transmitted:B. miyamotoi (hard tick relapsing fever), Borrelia burgdorferi and B. mayonii (Lyme disease), Ehrlichia muris eauclairensis (ehrlichiosis), Anaplasma phagocytophilum (anaplasmosis), Babesia microti (babesiosis), and Powassan virus. Remarks: The bite threat is highest in spring, summer, and fall, although adult ticks can attack during warmer winter days. Nymphs and adult females bite humans the most frequently.
Brown Dog Tick
Distribution:Rhipicephalus sanguineus can be found worldwide. Diseases Transmitted: Rocky Mountain spotted fever, especially in the Southwest U.S. and at the border between the U.S. and Mexico. Remarks: Dogs are the most common hosts for all tick life stages. However, these species also bite humans and other mammals.
Gulf Coast Tick
Distribution:Amblyomma maculatum’s habitat includes the Atlantic and Gulf coasts of the U.S. Diseases Transmitted:Rickettsia parkeri rickettsiosis spotted fever. Remarks: Larvae and nymphs feed on birds and small rodents, while adults on deer and other wild animals. Adult ticks mainly transmit R. parkeri to humans.
Lone Star Tick
Distribution: The southeastern, south-central, and eastern United States are home to Amblyomma americanum. Diseases Transmitted:Ehrlichia chaffeensis and Ehrlichia ewingii (human ehrlichiosis), Bourbon virus, Heartland virus, tularemia, STARI. According to available data, humans can develop alpha-gal syndrome (red meat allergy) due to bites from lone star ticks, although no other tick species are excluded. Remarks: A very dangerous tick that frequently attacks people. A white "lone star" on its back can distinguish the adult female. Tick saliva stings the bite area, but redness doesn’t necessarily mean infection. The disease agents are the nymphs and adult females.
Rocky Mountain Wood Tick
Distribution:Dermacentor andersoni is widespread throughout southwestern Canada and the Rocky Mountains, elevating up to 10,500 feet. Diseases Transmitted: Tularemia, Colorado tick fever, and Rocky Mountain spotted fever. Remarks: Adult ticks bite mammals, larvae, and nymphs – small rodents. They are most commonly associated with the transmission of pathogens to humans.
Western Blacklegged Tick
Distribution:Ixodes pacificus resides on the Pacific Coast of the U.S., mainly in northern California. Diseases Transmitted:Borrelia burgdorferi (Lyme disease), Anaplasma phagocytophilum (anaplasmosis), and B. miyamotoi (hard tick relapsing fever) are the most common. Remarks: Larvae and nymphs feed on lizards, birds, and rodents, and adults often feed on deer. Nymphs and adult females are reported more frequently, although all stages can bite humans.
