Tick-borne diseases

Last updated: August 12, 2022

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Tick-borne diseases are predominantly caused by pathogens that are transmitted by ticks (and sometimes other vectors), except tick paralysis, which is caused by a neurotoxin produced by the tick itself. Tick-borne diseases are typically associated with specific geographical regions. The most clinically significant tick-borne diseases in the US include Lyme disease, Rocky Mountain spotted fever (RMSF), babesiosis, ehrlichiosis, anaplasmosis, tularemia, Colorado tick fever, tick-borne relapsing fever, southern tick‑associated rash illness, and tick paralysis. While manifestations of these conditions vary, common symptoms include fever, flu-like symptoms, and skin rashes. Most tick-borne diseases are treated with antibiotics and patients usually respond well to treatment.

Lyme disease is covered in more detail in its own article.

Overview of tick-borne diseases [1]
Pathogen/cause US distribution

Clinical features

Diagnostics Treatment
Lyme disease
  • Upper midwestern and northeastern US
Rocky Mountain spotted fever (RMSF)
  • Rickettsia rickettsii
  • Midwestern, northeastern, and southern US
  • Midwestern (especially Minnesota and Wisconsin) and northeastern US
  • Mainly east of the Rocky Mountains
  • Some cases in the Southwest


  • Upper midwestern and northeastern US
  • Growing number of cases on the West Coast
Tularemia [2]
  • All states except Hawaii
Colorado tick fever (CTF) [3]
  • Western US
  • < 2 weeks after onset of symptoms: viral RNA detection by RT-PCR of blood sample
  • > 2 weeks after onset of symptoms: serum assay to detect CTFV-specific IgM antibodies
  • Supportive management only
Tick-borne relapsing fever [4]
  • Western US and Texas
  • Recurring episodes of high fever for 3 days and an afebrile period of 7 days
  • Arthralgia
  • Gastrointestinal symptoms
  • Macular rash or scattered petechiae
Southern tick‑associated rash illness (STARI)
  • Unknown
  • Southeastern and eastern US
Tick paralysis
  • Rocky Mountains and northwestern US
  • Remove the tick
  • Supportive therapy


Clinical features [6]

The rash may be less obvious in dark-skinned individuals; therefore, close inspection and a high degree of clinical suspicion are required. [7]

Diagnostics [7][8][9]

RMSF is a clinical diagnosis.

Do not delay treatment while waiting for confirmatory studies and do not discontinue treatment based solely on the results. [9]

RMSF is a nationally notifiable disease in the United States. Contact the state or local health department if a potential case is suspected. [7]

Differential diagnosis [9]


Initiate empiric antibiotic treatment immediately and consider consulting local infectious disease specialists. [9]

Treatment should be initiated as soon as RMSF is suspected, as it can be fatal if not treated early.

Disposition [9]

  • Consider hospitalization for patients who:
  • Escalate to critical care unit based on clinical condition.
  • In selected cases, consider discharge with oral antibiotics.

Prognosis [12]

  • If treated within the first 5 days, patients typically fully recover without hospitalization.
  • If treated after the first 5 days, symptoms are more severe and often require hospitalization. There is also a greater risk of long-term consequences of ischemia (e.g., amputations, paralysis, hearing loss, intellectual disability).
  • If not treated early enough, the disease can be fatal.

Ehrlichiosis is a nationally notifiable disease in the United States. Contact the state or local health department if a potential case is suspected. [7]

Anaplasmosis is a nationally notifiable disease in the United States. Contact the state or local health department if a potential case is suspected. [7]

References: [26]

  1. Simon LV, West B, McKinney WP. Tick Paralysis. StatPearls. 2020 .
  2. Rocky Mountain Spotted Fever (RMSF) - Epidemiology and Statistics. https://www.cdc.gov/rmsf/stats/index.html. Updated: April 7, 2020. Accessed: January 27, 2021.
  3. Snowden J, Simonsen KA. Rickettsia Rickettsiae. StatPearls. 2020 .
  4. Walls R, Hockberger R, Gausche-Hill M. Rosen's Emergency Medicine. Elsevier Health Sciences ; 2018
  5. Gottlieb M, Long B, Koyfman A. The Evaluation and Management of Rocky Mountain Spotted Fever in the Emergency Department: a Review of the Literature. J Emerg Med. 2018; 55 (1): p.42-50. doi: 10.1016/j.jemermed.2018.02.043 . | Open in Read by QxMD
  6. Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis — United States. MMWR Recomm Rep. 2016; 65 (2): p.1-44. doi: 10.15585/mmwr.rr6502a1 . | Open in Read by QxMD
  7. Todd SR, Dahlgren FS, Traeger MS, et al. No Visible Dental Staining in Children Treated with Doxycycline for Suspected Rocky Mountain Spotted Fever. J Pediatr. 2015; 166 (5): p.1246-1251. doi: 10.1016/j.jpeds.2015.02.015 . | Open in Read by QxMD
  8. Blanton LS. The Rickettsioses: A Practical Update.. Infect Dis Clin North Am. 2019; 33 (1): p.213-229. doi: 10.1016/j.idc.2018.10.010 . | Open in Read by QxMD
  9. RMSF: deadly, but preventable. https://www.cdc.gov/ncezid/dvbd/media/rmsf.html. Updated: June 10, 2019. Accessed: January 27, 2021.
  10. Belongia EA. Epidemiology and impact of coinfections acquired from Ixodes ticks.. Vector Borne Zoonotic Dis. 2002; 2 (4): p.265-73. doi: 10.1089/153036602321653851 . | Open in Read by QxMD
  11. DPDx - Laboratory Identification of Parasites of Public Health Concern - Babesiosis. https://www.cdc.gov/dpdx/babesiosis/index.html. Updated: October 30, 2017. Accessed: January 28, 2021.
  12. Vannier E, Gewurz BE, Krause PJ. Human babesiosis.. Infect Dis Clin North Am. 2008; 22 (3): p.469-88, viii-ix. doi: 10.1016/j.idc.2008.03.010 . | Open in Read by QxMD
  13. CDC - Ehrlichiosis. https://www.cdc.gov/ticks/tickbornediseases/ehrlichiosis.html. Updated: October 1, 2020. Accessed: January 27, 2021.
  14. Bennett JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Elsevier Saunders ; 2015
  15. Ismail N, Bloch KC, McBride JW. Human ehrlichiosis and anaplasmosis.. Clin Lab Med. 2010; 30 (1): p.261-92. doi: 10.1016/j.cll.2009.10.004 . | Open in Read by QxMD
  16. Guzman N, Yarrarapu SNS, Beidas SO. Anaplasma Phagocytophilum (Anaplasmosis). StatPearls. 2020 .
  17. Tularemia. https://www.cdc.gov/tularemia/index.html. Updated: September 27, 2016. Accessed: December 11, 2017.
  18. WHO Guidelines on Tularaemia.
  19. Colorado Tick Fever (CTF) - Symptoms & Treatment. https://www.cdc.gov/coloradotickfever/symptoms-treatment.html. Updated: December 3, 2018. Accessed: January 27, 2021.
  20. Tickborne Diseases of the United States - Colorado Tick Fever. https://www.cdc.gov/ticks/tickbornediseases/ctf.html. Updated: January 10, 2019. Accessed: January 27, 2021.
  21. Snowden J, Yarrarapu SNS, Oliver TI. Relapsing Fever. StatPearls. 2020 .
  22. Tick-borne Relapsing Fever (TBRF). https://www.cdc.gov/relapsing-fever/clinicians/index.html. Updated: January 8, 2016. Accessed: December 11, 2017.
  23. Southern Tick–Associated Rash Illness - STARI or Lyme?. https://www.cdc.gov/stari/disease/index.html. Updated: November 19, 2018. Accessed: January 27, 2021.
  24. Southern Tick–Associated Rash Illness - Symptoms, Diagnosis and Treatment. https://www.cdc.gov/stari/symptoms/index.html. Updated: November 19, 2018. Accessed: January 27, 2021.
  25. Tickborne Diseases of the United States: A Reference Manual for Health Care Providers.
  26. Colorado Tick Fever. https://www.cdc.gov/coloradotickfever/healthcareproviders.html. Updated: January 13, 2015. Accessed: December 11, 2017.

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