Medicine:Tick-borne disease

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Tick-borne disease
SpecialtyInfectious disease

Tick-borne diseases, which afflict humans and other animals, are caused by infectious agents transmitted by tick bites.[1] They are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa.[2] The economic impact of tick-borne diseases is considered to be substantial in humans,[3] and tick-borne diseases are estimated to affect ~80 % of cattle worldwide.[4]

The occurrence of ticks and tick-borne illnesses in humans is increasing.[5] Tick populations are spreading into new areas, in part due to climate change.[6][7] Tick populations are also affected by changes in the populations of their hosts (e.g. deer, cattle, mice, lizards) and those hosts' predators (e.g. foxes). Diversity and availability of hosts and predators can be affected by deforestation and habitat fragmentation.[6]

Because individual ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment.[2] As the incidence of tick-borne illnesses increases and the geographic areas in which they are found expand, health workers increasingly must be able to distinguish the diverse, and often overlapping, clinical presentations of these diseases.[8]

(As of 2020) 18 tick-borne pathogens have been identified in the United States according to the Centers for Disease Control[8] and at least 27 are known globally.[6][9][10] New tick-borne diseases have been discovered in the 21st century, due in part to the use of molecular assays and next-generation sequencing.[11]



A tick crawling on a human head in a wooded area near LeRoy, Michigan.

Ticks tend to be more active during warmer months, though this varies by geographic region and climate. Areas with woods, bushes, high grass, or leaf litter are likely to have more ticks. Those bitten commonly experience symptoms such as body aches, fever, fatigue, joint pain, or rashes. People can limit their exposure to tick bites by wearing light-colored clothing (including pants and long sleeves), using insect repellent with 20%–30% N,N-Diethyl-3-methylbenzamide (DEET), tucking their pants legs into their socks, checking for ticks frequently, and washing and drying their clothing in a hot dryer.[12][13]

According to the World Health Organization, tick-to-animal transmission is difficult to prevent because animals do not show visible symptoms; the only effective prevention relies on killing ticks on the livestock production facility.[14]

Tick removal

Ticks should be removed as soon as safely possible once discovered. They can be removed either by grasping tweezers as close to the mouth as possible and pulling without rotation; some companies market grooved tools that rotate the hypostome to facilitate removal. Chemical methods to make the tick self-detach, or trying to pull the tick out with one’s fingers, are not efficient methods.[15]


In general, specific laboratory tests are not available for rapid diagnosis of tick-borne diseases. Due to their seriousness, antibiotic treatment is often justified based on clinical presentation alone.

Assessing risk

For a person or pet to acquire a tick-borne disease requires that the individual gets bitten by a tick and that the tick feeds for a sufficient period of time. The feeding time required to transmit pathogens differs for different ticks and different pathogens. Transmission of the bacterium that causes Lyme disease is well understood to require a substantial feeding period.[16] In general, soft ticks (Argasidae) transmit pathogens within minutes of attachment because they feed more frequently, whereas hard ticks (Ixodidae) take hours or days, but the latter are more common and harder to remove.[15]

For an individual to acquire infection, the feeding tick must also be infected. Not all ticks are infected. In most places in the US, 30-50% of deer ticks will be infected with Borrelia burgdorferi (the agent of Lyme disease). Other pathogens are much more rare. Ticks can be tested for infection using a highly specific and sensitive qPCR procedure. Several commercial labs provide this service to individuals for a fee. The Laboratory of Medical Zoology (LMZ), a nonprofit lab at the University of Massachusetts, provides a comprehensive TickReport [17] for a variety of human pathogens and makes the data available to the public.[18] Those wishing to know the incidence of tick-borne diseases in their town or state can search the LMZ surveillance database.[18]


Major tick-borne diseases include:


  • Lyme disease or borreliosis
  • Relapsing fever (tick-borne relapsing fever, different from Lyme disease due to different Borrelia species and ticks)
    • Organisms: Borrelia species such as B. hermsii, B. parkeri, B. duttoni, B. miyamotoi
    • Vector: Ornithodoros species
    • Regions : Primarily in Africa, Spain, Saudi Arabia, Asia in and certain areas of Canada and the western United States
    • Symptoms: Relapsing fever typically presents as recurring high fevers, flu-like symptoms, headaches, and muscular pain, with less common symptoms including rigors, joint pain, altered mentation, cough, sore throat, painful urination, and rash[22]
    • Treatment: Antibiotics are the treatment for relapsing fever, with doxycycline, tetracycline, or erythromycin being the treatment of choice.[23]
  • Typhus Several diseases caused by Rickettsia bacteria (below)
  • Rocky Mountain spotted fever
    • Organism: Rickettsia rickettsii
    • Vector: Wood tick (Dermacentor variabilis), D. andersoni
    • Region (US): East, Southwest
    • Vector: Amblyomma cajennense
    • Region (Brazil): São Paulo, Rio de Janeiro, Minas Gerais.
    • Symptoms:Fever, headache, altered mental status, myalgia, and rash
    • Treatment: Antibiotic therapy, typically consisting of doxycycline or tetracycline
  • Helvetica spotted fever
    • Organism: Rickettsia helvetica
    • Region(R. helvetica): Confirmed common in ticks in Sweden, Switzerland, France, and Laos[24]
    • Vector/region(s)#1: Ixodes ricinus is the main European vector.[24]
    • Symptoms: Most often small red spots, other symptoms are fever, muscle pain, headache and respiratory problems[24]
    • Treatment: Broad-spectrum antibiotic therapy is needed, phenoxymethylpenicillin likely is sufficient.[24]
  • Human granulocytic anaplasmosis (formerly human granulocytic ehrlichiosis or HGE)
    • Organism: Anaplasma phagocytophilum (formerly Ehrlichia phagocytophilum or Ehrlichia equi)
    • Vector: Lone star tick (Amblyomma americanum), I. scapularis
    • Region (US): South Atlantic, South-central
  • Bartonella: Bartonella transmission rates to humans via tick bite are not well established [25] but Bartonella is common in ticks. For example: 4.76% of 2100 ticks tested in a study in Germany [26]
  • Tularemia
    • Organism: Francisella tularensis, A. americanum
    • Vector: D. variabilis, D. andersoni
    • Region (US): Southeast, South-central, West, widespread





  • Alpha-gal allergy - Alpha-gal syndrome is likely caused by a hypersensitivity reaction to the Alpha-gal (Galactose-alpha-1,3-galactose) sugar molecule introduced by ticks while feeding on a human host. The immune reaction can leave people with an allergy to red meat and other mammalian derived products.[32]

See also


  1. "Let's Do a Tick Check - These pervasive bloodsuckers can give you more than just Lyme disease. Here's how to protect yourself. (Interactive)". The New York Times. 11 June 2021. 
  2. 2.0 2.1 Kumar, Manish; Sharma, Aniket; Grover, Prashant (13 February 2019). "Triple Tick Attack". Cureus 11 (2): e4064. doi:10.7759/cureus.4064. PMID 31016091. 
  3. Mac, Stephen; da Silva, Sara R.; Sander, Beate (4 January 2019). "The economic burden of Lyme disease and the cost-effectiveness of Lyme disease interventions: A scoping review". PLOS ONE 14 (1): e0210280. doi:10.1371/journal.pone.0210280. ISSN 1932-6203. PMID 30608986. 
  4. Rochlin, Ilia; Toledo, Alvaro (1 June 2020). "Emerging tick-borne pathogens of public health importance: a mini-review" (in en). Journal of Medical Microbiology 69 (6): 781–791. doi:10.1099/jmm.0.001206. ISSN 0022-2615. PMID 32478654. 
  5. "Lyme and Other Tickborne Diseases Increasing" (in en-us). 21 October 2021. 
  6. 6.0 6.1 6.2 Chrobak, Ula (3 February 2022). "Lyme and other tick-borne diseases are on the rise. But why?". Knowable Magazine. doi:10.1146/knowable-020222-1. Retrieved 4 March 2022. 
  7. Gilbert, Lucy (7 January 2021). "The Impacts of Climate Change on Ticks and Tick-Borne Disease Risk". Annual Review of Entomology 66 (1): 373–388. doi:10.1146/annurev-ento-052720-094533. ISSN 0066-4170. PMID 33417823. Retrieved 4 March 2022. 
  8. 8.0 8.1 Tick-Borne Disease Working Group. 2020 Report to Congress. Washington, D.C.: U.S. Department of Health and Human Services. 2020. Retrieved 4 March 2022. 
  9. Paddock, Christopher D.; Lane, Robert S.; Staples, J. Erin; Labruna, Marcelo B. (21 September 2016) (in en). Changing paradigms for tick-borne diseases in the Americas. National Academies Press (US). Retrieved 4 March 2022. 
  10. Zhao, Guo-Ping; Wang, Yi-Xing; Fan, Zheng-Wei; Ji, Yang; Liu, Ming-jin; Zhang, Wen-Hui; Li, Xin-Lou; Zhou, Shi-Xia et al. (17 February 2021). "Mapping ticks and tick-borne pathogens in China" (in en). Nature Communications 12 (1): 1075. doi:10.1038/s41467-021-21375-1. ISSN 2041-1723. PMID 33597544. PMC 7889899. Retrieved 4 March 2022. 
  11. Tokarz, Rafal; Lipkin, W. Ian (1 July 2021). "Discovery and Surveillance of Tick-Borne Pathogens". Journal of Medical Entomology 58 (4): 1525–1535. doi:10.1093/jme/tjaa269. ISSN 0022-2585. PMID 33313662. PMC 8285023. Retrieved 4 March 2022. 
  12. "Tick-Borne Diseases". Centers for Disease Control and Prevention: National Institute for Occupational Safety and Health. 
  13. "Prevention of tick-borne diseases: an overview". The British Journal of General Practice 66 (650): 492–494. September 2016. doi:10.3399/bjgp16X687013. PMID 27563139. 
  14. "Crimean-Congo haemorrhagic fever" (in en). 
  15. 15.0 15.1 "Removal of ticks: a review of the literature". Euro Surveillance 11 (8): E060817.4. August 2006. doi:10.2807/esw.11.33.03027-en. PMID 16966784. 
  16. "TickEncounter Resource Center". University of Rhode Island. 
  17. "TickReport". Laboratory of Medical Zoology. University of Massachusetts. 
  18. 18.0 18.1 "Tick-Borne Disease Network". Laboratory of Medical Zoology. University of Massachusetts. 
  19. "Host association of Borrelia burgdorferi sensu lato: A review". Ticks and Tick-Borne Diseases 12 (5): 101766. September 2021. doi:10.1016/j.ttbdis.2021.101766. PMID 34161868. 
  20. Mayo Clinic Staff. "Lyme disease: Symptoms". Mayo Clinic. 
  21. Mayo Clinic Staff. "Lyme disease: Treatments and drugs". Mayo Clinic. 
  22. Relapsing fever at eMedicine.
  23. Relapsing fever~treatment at eMedicine.
  24. 24.0 24.1 24.2 24.3 "Seroreactivity for spotted fever rickettsiae and co-infections with other tick-borne agents among habitants (sic) in central and southern Sweden". European Journal of Clinical Microbiology & Infectious Diseases 32 (3): 317–323. March 2013. doi:10.1007/s10096-012-1742-3. PMID 22961007. 
  25. "Bartonella spp. Bacteremia and rheumatic symptoms in patients from lyme disease-endemic region". Emerging Infectious Diseases 18 (11): 1918–1919. November 2012. doi:10.3201/eid1811.120675. PMID 23092626. 
  26. "Bartonella spp. infection rate and B. grahamii in ticks". Emerging Infectious Diseases 18 (10): 1689–1690. October 2012. doi:10.3201/eid1810.120390. PMID 23017501. 
  27. "Zoonotic tick-borne flaviviruses". Veterinary Microbiology. Zoonoses: Advances and Perspectives 140 (3–4): 221–228. January 2010. doi:10.1016/j.vetmic.2009.08.024. PMID 19765917. 
  28. "Powassan Virus | Powassan | CDC" (in en-us). 
  29. "Notes from the field: Heartland virus disease - United States, 2012-2013". MMWR. Morbidity and Mortality Weekly Report 63 (12): 270–271. March 2014. PMID 24670929. PMC 5779346. 
  30. "Chinese researchers highlight new tick-borne disease, Alongshan virus". CIDRAP - Center for Infectious Disease Research and Policy. Minneapolis, MN: University of Minnesota. May 29, 2019. 
  31. "Ticks". Department of Entomology, University of Sydney and Westmead Hospital. November 7, 2003. 
  32. Crispell, Gary; Commins, Scott P.; Archer-Hartman, Stephanie A.; Choudhary, Shailesh; Dharmarajan, Guha; Azadi, Parastoo; Karim, Shahid (17 May 2019). "Discovery of Alpha-Gal-Containing Antigens in North American Tick Species Believed to Induce Red Meat Allergy". Frontiers in Immunology. 10: 1056. PMC 6533943. PMID 31156631

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