Tick-Borne Diseases: Awareness and Prevention

Infected female deer tick on human skin.Tick-borne diseases (TBDs) range from mild infections to life-altering chronic diseases. They pose a significant and growing threat in the United States, Europe, and worldwide. [1, 2, 3] According to the United States Environmental Protection Agency, the incidence of Lyme disease rose 93% from 3.74 to 7.21 reported cases per 100,000 people between 1991 and 2018. [4] Apart from Lyme disease being the most well-known TBD, ticks are also vectors for other serious illnesses. These include viral, parasitic, and bacterial pathogens such as babesiosis, Powassan virus, bourbon virus, spotted fever rickettsiosis, and tick-borne encephalitis. [5, 6] Climate change, deforestation, and urbanization are some of the reasons behind this ticking time bomb. [7]

As TBDs become more prevalent, the need for reliable and accurate diagnostic tools is increasingly urgent, especially as traditional serological testing methods are famously unreliable. [8] It’s important to stay up-to-date so you’re equipped to address this trend and educate the public on how to stay safe.

Understanding Vector-Borne Infections

Typically transmitted by blood-feeding arthropods such as ticks, fleas, and mosquitoes, vector-borne diseases (VBDs) cause 700,000 deaths per year. [9] However, ticks are responsible for more than 75% of all VBD cases in the United States. [2, 8]

Why Are Ticks So Good at Spreading Diseases?

Evolutionary adaptations have made ticks particularly skilled at latching onto hosts and feeding for extended periods. There are several reasons ticks are especially adept at spreading pathogens.

Transmission Method: Ticks are slow feeders. Other than Powassan virus, which only takes 15 minutes to transmit, most TBDs need time. [10] For instance, a Lyme disease infection usually takes between 36 and 48 hours to transmit. [11] Compared to other arthropods, such as mosquitoes, which feed quickly, ticks’ prolonged attachment bolsters the likelihood of infection.

Stealth: A tick’s saliva blocks pain and itching, serves as an anticoagulant, and modulates immune response and wound healing as they feed. [12] This is how they’re able to remain attached for so long without the host noticing and brushing it off.

Lifespan and Lifecycle: Mosquitoes live for 4 days to a month, but ticks can survive for 2–3 years, provided they feast on a blood meal to progress through each phase of their lifecycle. [13, 14] As such, they have plenty of time to attach to hosts and stockpile a supply of pathogens for future transmission.

Questing: Ticks display questing behavior, which involves waiting in plants and foliage and extending their front legs until a suitable host arrives. [15] Older adults and individuals who spend a lot of time doing gardening and yard work are at the highest risk of a bite. [16]

Common Tick-Borne Diseases: A Closer Look at Lyme Disease

Lyme disease is the most common VBD in the world, with an estimated 476,000 cases diagnosed and treated each year in the United States and 200,000 cases reported annually in Western Europe. [17] It’s even a growing concern in areas that had barely any incidence previously, like Canada. In 2009, there were only 144 reported cases there, rising to 2,636 (almost 20 times the number of cases) in 2019. [18] 

Lyme Disease Symptoms

Lyme disease is mainly caused by Borrelia burgdorferi and transmitted via the Ixodes tick, also known as the blacklegged or deer tick. Symptoms manifest in three distinct stages:

Early localized stage (3-30 days following a bite): During this stage, a distinctive circular rash called erythema migrans, which can expand beyond 12 inches in diameter and often resembles a bull’s-eye, appears in 70% to 80% of infected individuals. Flu-like symptoms such as fever, fatigue, chills, muscle and joint aches, headache, and swollen lymph nodes are also common.

Early disseminated stage (weeks to months following a bite): As the infection progresses, multiple rashes may develop on various parts of the body. Additional symptoms can include facial paralysis (Bell’s palsy), neck stiffness, and joint pain.

Late disseminated stage: (months to years following a bite): If left untreated, Lyme disease can lead to chronic joint inflammation, carditis causing irregular heartbeat or palpitations, nerve pain, neuropathy, and inflammation of the spinal cord and brain.[19]

Lyme Disease Diagnosis

Diagnosing Lyme disease traditionally involves a combination of clinical evaluation and laboratory tests. The standard tool is two-tiered serological testing:

  1. Enzyme-linked immunosorbent assay (ELISA): An initial test to detect antibodies — but a positive result doesn’t confirm Lyme unequivocally.
  2. Western blot: Confirmatory test in case ELISA is positive or equivocal. [20]

Symptom variability and serological tests’ limitations make early and accurate diagnosis difficult.

Is There a Cure for Lyme Disease?

Effective antibiotic treatment exists for Lyme disease, but a cure isn’t always possible. That’s because Borrelia burgdorferi exhibits immune evasion and can persist in a dormant state within the body.

Successful treatment of Lyme disease hinges on early diagnosis and antibiotic treatment using medicines such as doxycycline or amoxicillin. However, treating post-treatment Lyme disease syndrome (PTLDS) remains an area of active investigation. Standardized protocols are lacking, and the efficacy of extended antibiotic regimens is unclear. [21]

Other Tick-Borne Diseases

Other tick-borne diseases include:

Rocky Mountain Spotted Fever (RMSF): Caused by the bacterium Rickettsia rickettsii, RMSF often presents with a sudden onset of fever, headache, rash (typically starting on wrists and ankles), and muscle pain. Without prompt treatment, it can be severe or even fatal.

Anaplasmosis: This disease, caused by Anaplasma phagocytophilum, usually manifests with fever, chills, severe headache, muscle aches, and sometimes gastrointestinal symptoms such as nausea and diarrhea. It can lead to serious complications if not treated early.

Ehrlichiosis: Caused by bacteria of the Ehrlichia species, ehrlichiosis often results in fever, headache, chills, muscle pain, and malaise. In some cases, patients may also experience a rash, gastrointestinal symptoms, and confusion.

Babesiosis: This infection, caused by Babesia parasites, primarily affects red blood cells. Symptoms can range from mild to severe and include fever, chills, sweats, headache, body aches, loss of appetite, nausea, and fatigue. Severe cases can cause hemolytic anemia and require hospitalization.

Tick Myths vs. Facts: Debunking Common Misconceptions

Myth Fact
You can feel when a tick bites you. Ticks’ saliva is adapted for stealth. [11]
No rash means no Lyme disease. There’s no rash with approximately 20%-30% of Lyme disease cases. [18]
Lyme disease is the only serious illness transmitted by ticks. Ticks can transmit a variety of serious diseases other than Lyme, such as anaplasmosis, babesiosis, and Powassan virus disease. [22]
Removing a tick with heat, such as a hot match, is effective. Using heat can increase saliva production and make disease transmission more likely. [23] 
Ticks only live in wooded areas. Ticks live in urban parks and gardens, not just in dense forests or rural areas. [24]
You are safe from ticks in the winter. Ticks can be active year-round, but their activity is reduced in winter months. [3]

Geographic and Seasonal Impacts of Tick-Borne Diseases

Geography and seasons play a pivotal role in the prevalence and spread of tick-borne diseases. In North America, Lyme disease is most prevalent in the Northeast and Upper Midwest due to an abundance of blacklegged ticks. The American dog tick transmits Rocky Mountain spotted fever, and it’s more common in the southern states.

Spring and summer see peak activity for nymphs and adult ticks, with nymphs posing a particular threat as their small size makes them even more difficult to detect. Tick activity decreases in autumn and winter, but they can remain active during warmer winters or in regions with mild winters.

In recent years, the effects of climate change have resulted in warmer temperatures and milder winters, which has extended the ticks’ active seasons and expanded their geographical range. Additionally, changes in land use, such as reforestation and suburban development, have created ideal habitats for ticks and their hosts, including deer and rodents. Increased human outdoor activity in these areas has also heightened the risk of tick encounters and tick-borne diseases.

Staying Safe Through Prevention and Awareness

Preventing tick bites and raising public awareness are the only ways to reduce the spread of tick-borne diseases.

Tips for prevention include using insect repellent containing DEET, wearing permethrin-coated clothes, and covering limbs. After spending time outdoors, perform routine tick checks on your body, clothing, pets, and equipment after spending time outdoors. Properly removing ticks with fine-tipped tweezers as close to the skin’s surface as possible is also crucial. [25]

Sources

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