Tick with tick-borne disease burrowing into person's skin

Why have tick-borne diseases increased?

Written on May 22, 2023 by Sendra Yang, PharmD, MBA. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

The prevalence of tick-borne diseases in the United States has risen within the past decade, becoming an increasing public health concern.[1] Each year, close to half a million people are diagnosed and treated for tick-borne diseases.[1] Although many tick species exist, only a few types of ticks transmit bacteria, viruses, parasites, or pathogens that cause diseases.[2] These include the American dog tick, black-legged tick, brown dog tick, gulf coast tick, and lone star tick.[2] These tick species vary in their geographical distribution in the United States.

Ticks go through four life stages: egg, larva, nymph, and adult.[4] They require blood at each stage to survive. When ticks feed on blood, they can pass pathogens responsible for illnesses such as Lyme disease or Rocky Mountain fever.[2]

Tick-borne diseases tend to have similar signs and symptoms. The most common symptoms of tick-related illnesses include fever or chills, aches and pains, headache, and fatigue, mimicking many other diseases.[3] People with Lyme disease may also have joint pain or rash.[3] Read on to learn why tick-borne diseases have increased.

Factors contributing to the increase in tick-borne diseases

There are a number of contributing factors to the increase in tick-borne diseases.

Climate change

Climate warming and other environmental changes have contributed to the expansion of the range of several tick species into higher latitudes in North America.[6] Ticks flourish in warm and humid environments, and as these conditions become more prevalent with climate change, their population is expected to increase.[6-8] The number of reported cases of Lyme disease in the colder climates of the northeastern United States has increased over time, potentially due to the warmer temperatures.[8]

Changes in host species

Animals play a crucial role in the transmission cycle of tick-borne pathogens.[4,5] Wild animal hosts such as mice or deer are responsible for providing pathogens to immature ticks, and these wild animals are the primary reservoir hosts for most tick-borne diseases.[4] Climate change impacts the interaction of ticks and hosts, greatly influencing the spread of tick-borne diseases.[7] Rising temperatures will favor expanding the range of rodents and deer, increasing their abundance and activity in geographical regions where they may have previously had limited activity. Wildlife populations can impact the number of ticks and their infection rates.[4]

Human encroachment

As people move into developments that were once forest habitats, ticks have increased opportunities to come into contact with people.[9-10] It is well-established that tick populations are higher in forest habitats than in developed areas.[9] As a result, land-use changes have important implications for the distribution and abundance of tick hosts and vector sources of human disease associated with ticks.[10]

What can you do to prevent contracting tick-borne diseases?

The best way to avoid tick-borne diseases is to avoid contact with ticks. With proper planning, you can reduce your risk of exposure if you plan to be in areas with possible tick activity. Your behavior and tick awareness can help reduce the risk of tick-borne diseases. To reduce your exposure risk, according to the CDC, you should take the following precautions [11,12]:

  1. Wear long sleeves and pants to prevent your skin from coming into contact with a tick.
  2. After returning from an area known to have ticks, remove clothing before returning indoors.
  3. Use insect repellents.
  4. Check your body, pets, or children after going outdoors.
  5. Apply pesticide outdoors to create a safe zone from ticks.

Summary and next steps

The rise of tick-borne diseases presents substantial challenges for public health. The complex nature of tick-borne diseases can mimic other illnesses and present with a wide range of symptoms that can be medically challenging to diagnose. Misdiagnosis or delayed treatment can result in prolonged suffering and chronic health complications.[13] Factors contributing to this increase include climate change, human encroachment, shifts in wildlife populations, human behavior, and challenges public health systems face. Limited awareness of preventive measures further contributes to the problem.[3]

If you think you may have been exposed to a tick, an initial step is to get tested for tick-borne diseases. Everlywell has a Lyme Disease Test that will allow you to test from the comfort of your home. If your lab test result is positive, a healthcare provider will contact you to discuss the next steps and how you may be diagnosed and treated, if appropriate.

Lyme disease prevalence: what you need to know

Who's at risk of Lyme disease?

Where is Lyme disease common?


  1. Understanding Lyme and other Tick-borne Diseases. Centers for Disease Control and Prevention. https://www.cdc.gov/ncezid/dvbd/media/lyme-tickborne-diseases-increasing.html. Last Reviewed May 11, 2022. Accessed May 17, 2023.
  2. Regions where ticks live. Centers for Disease Control and Prevention. https://www.cdc.gov/ticks/geographic_distribution.html. Last Reviewed December 5, 2022. Accessed May 17, 2023.
  3. Symptoms of tick-borne illness. Centers for Disease Control and Prevention. https://www.cdc.gov/ticks/symptoms.html. Last Reviewed August 5, 2021. Accessed May 17, 2023.
  4. How ticks spread disease. Centers for Disease Control and Prevention. https://www.cdc.gov/ticks/life_cycle_and_hosts.html. Last Reviewed September 21, 2020. Accessed May 17, 2023.
  5. The life cycle of a tick with photos. Tick Talk. May 10, 2021. https://www.ticktalk.org/lets-talk-ticks/tick-life-cycle/. Accessed May 17, 2023.
  6. Bouchard C, Dibernardo A, Koffi J, Wood H, Leighton PA, Lindsay LR. N Increased risk of tick-borne diseases with climate and environmental changes. Can Commun Dis Rep. 2019;45(4):83-89. doi:10.14745/ccdr.v45i04a02. https://pubmed.ncbi.nlm.nih.gov/31285697/.
  7. Randolph SE. Is expert opinion enough? A critical assessment of the evidence for potential impacts of climate change on tick-borne diseases. Anim Health Res Rev.2013;14(2):133-137. doi:10.1017/S1466252313000091. https://pubmed.ncbi.nlm.nih.gov/24067445/.
  8. Climate Change Indicators: Lyme Disease. EPA. https://www.epa.gov/climate-indicators/climate-change-indicators-lyme-disease. Accessed May 17, 2023.
  9. Guerra M, Walker E, Jones C, et al. Predicting the risk of Lyme disease: habitat suitability for Ixodes scapularis in the north central United States. Emerg Infect Dis. 2002;8(3):289-297. doi:10.3201/eid0803.010166. https://pubmed.ncbi.nlm.nih.gov/11927027/.
  10. Jones BA, Grace D, Kock R, et al. Zoonosis emergence linked to agricultural intensification and environmental change. Proc Natl Acad Sci U S A.2013;110(21):8399-8404. doi:10.1073/pnas.1208059110. https://www.pnas.org/doi/10.1073/pnas.1208059110.
  11. Preventing tick bites. Centers for Disease Control and Prevention. https://www.cdc.gov/ticks/avoid/on_people.html. Last Reviewed July 1, 2020. Accessed May 17, 2023.
  12. Preventing ticks in the yard. Centers for Disease Control and Prevention. https://www.cdc.gov/ticks/avoid/in_the_yard.html. Last Reviewed February 22, 2019. Accessed May 17, 2023.
  13. Post-treatment lyme disease syndrome. Centers for Disease Control and Prevention. https://www.cdc.gov/lyme/postlds/index.html. Last Reviewed January 10, 2022. Accessed May 17, 2023.
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