I stood there in front of the mirror, in my little bedroom in Maine, jaw to the floor, staring at the four-inch-wide, red, raised bullseye rash on my side, and all I could think was Lyme disease. I suspected Lyme the second I saw it, but I kept zeroing in on the word disease. It had terrifying connotations, conjuring up images of dirtiness, of defectiveness, of sickness, of the end of my health as I knew it. The word disease came attached with so much stigma in my mind that I refrained from sharing the experience for three years. This target on my body made me ask, "Why me?" For a long time, I couldn't find an answer. But now that I've had friends and family struggle with it, I have realized I'm not alone and the importance of spreading awareness.
My rash appeared over the course of 48 hours and stuck around for 2 weeks. I hadn't noticed I had been bitten, as there was no tick in sight. Over the course of the next few weeks, even light touch brought searing pain. Forget sleep. Every time I rolled onto my right side, I'd wake up—up to 5 times per night. I was also concurrently trying to fight Epstein Barr Virus, and the combination of these two infections resulted in the worst mental fog of my life.
My combined symptoms included:
fatigue, low energy - sleeping ~15 hours a night
intense, phlegmy coughing / congestion in the morning
waking up multiple times at night
sweating despite minimal blankets / clothes / fan
extremely deep, dark orange urine
swollen lymph nodes
general inability to focus
Thankfully, after a 3-week course of doxycycline and 2-3 months of feeling "not myself," I eventually made full recovery, which deepened my sense of gratitude for future moments of clarity. I was lucky that my symptoms were unambiguous and that I caught it early, grateful a simple treatment option existed when I needed it.
Prevalence and Incidence of Lyme Disease
Little did I know, Maine has one of the highest Lyme disease rates in the country. According to the CDC, there are an estimated 329,000 new cases in the US each year, but several scientists believe it is severely underreported and actually as high as 1 million cases a year (Nelson, 2015 & Stricker, 2014). With increasing average temperatures the past several years, black-legged deer ticks are on the rise, and Lyme disease rates are climbing.
According to CDC data, most cases were reported in NY, PA, and NJ. Another interactive map shows where Lyme disease is most prevalent using the underreported CDC data. Overall, we still see trends towards increasing Lyme incidence and highest prevalence in the northeast.
How is Lyme disease transmitted?
Lyme disease, or borreliosis, is transmitted by at least 21 of 52 known species of Borrelia, a spiral-shaped spirochete bacteria. Borrelia burgdorferi and B. mayonii (a newly discovered species in the Midwest) are known to cause Lyme disease in the US, while B. afzelii and B. garinii are found in Europe and Asia (Pritt, 2016). Rodents, birds, and deer are all competent vectors for these bacteria. Animals are bitten by infected ticks, which can then cause future ticks that bite that animal to become infected. This is how Lyme disease spreads.
Why is Lyme disease most prevalent in the northeast?
According to Vector Disease Control International, there are three major reasons for the increasing rates of Lyme disease in New England and Mid-Atlantic states:
Milder winters, longer falls, and warmer springs contribute to longer seasonal activity of deer ticks. This has enabled ticks to expand their habitat range.
The northeast has seen an overpopulation of white-tailed deer in recent years.
Humans increase their outdoor activity during warmer months, increasing exposure to ticks.
If the south is warmer, why are Lyme disease rates lower there?
According to the US Geological Survey, low humidity and high temperature is a deadly combination for ticks. Ticks can survive high temperature and high humidity by burrowing in the forest bed, where they can keep cool. This is what they tend to do in the south, where it's generally warmer. As a result, they're less likely to encounter humans.
Symptoms of Lyme Disease:
Lyme disease symptoms appear in 3-30 days. Lyme bacteria can move to your central nervous system, muscles, joints, eyes, and heart.
Rashes – erythema migrans (bullseye) or solid red oval
Achy, stiff, or swollen joints
Headaches, dizziness, fever
Night sweats and sleep disturbances
Difficulty concentrating and memory loss
Sensitivity to light and vision changes
Heart problems, lightheadedness, shortness of breath, heart palpitations
Mood changes – irritable, anxious, depressed
Unexplained pain/sensations: tinnitus, hearing loss, jaw pain/toothaches unrelated to tooth decay/infection
Treatment: Most people treated with 3 weeks of antibiotics have good prognosis. Shorter courses led to 40% relapse.
Prevention & Tick Repellents: Conventional vs. Naturally Derived
Is DEET Safe?
DEET is a pesticide derivative of toluene, a class of organic solvents used in rubber and plastic cements and paint removers. DEET works through its unpleasant odor: it masks the smell of humans and stimulates the insect's olfactory system differently so the human is not detected or the insect is confused by the cues.
Americans are concerned about DEET. A 2018 Consumer Reports nationally representative survey of 2,052 adults found that 25% of Americans said they avoid using insect repellents with DEET. And about a third said they thought repellents containing DEET are not as safe as those that don't have the chemical.
According to Pharmaceutical Information Associates Ltd., up to 56% of DEET applied to the skin is absorbed and 17% is absorbed into the bloodstream. DEET can cross the placenta and can be detected in fetal blood. Children are more sensitive to DEET than adults. DEET was reported to cause neurological effects like seizures in young children, but they were exposed to unusually high concentrations (Corbel, 2009).
Even if studies have shown DEET is safe on its own, it is important to note that combinations of chemicals can work synergistically and have harmful effects that are poorly characterized. Long-term and epigenetic effects are possible, and it may take multiple generations for bioaccumulation to observe an adverse effect. One Duke University study found that daily skin application of DEET to rats for 2 months in doses equivalent to those in humans caused neurons in the cerebral cortex, hippocampus, and cerebellum to die. These rats had impairments in muscle movement, learning, memory, and concentration.
Overall, DEET has been used for over 50 years by hundreds of millions of people, and adverse events from DEET are rare. Despite this, natural and effective alternatives to DEET exist.
Other Tick Repellents
DEET, picaridin, permethrin, IR3535, and oil of lemon eucalyptus are marketed as the most effective insect repellents that diminish the risk of a tick bite.
IR3535 was developed by Merck in the 1970s and is similar structurally to the amino acid B-alanine. It has been found to have the longest lasting repellent activity against black-legged ticks (Lupi, 2013).
Permethrin is a synthetic derivative of the insecticide pyrethrum, which comes from chrysanthemums. It is biodegradeable but also highly toxic to bees, cats, and marine life, and its recommended application is to clothes, not skin. The EPA considers it a possible carcinogen when ingested, as it was found to cause liver and lung tumors in mice.
Picaridin is an odorless insect repellent made by Bayer in the 1980s. It was approved for sale in the US in 2005. It is a synthetic derivative of a plant extract of the genus Piper, a component of black pepper. Long-term safety is not known. Around 60% of applied picaridin is absorbed by the skin. According to the National Pesticide Information Center, it is moderately toxic to fish and algae and can bioaccumulate. A 2-year study of rodents given topical picaridin found that the higher the dose, the heavier their livers.
Oil of lemon eucalyptus (which is different from the essential oil) was formulated in the 1960s. It is refined to increase the concentration of one of its component terpenoids, para-menthane-1,3-diol, or PMD, from 1 to 65%. According to EWG, studies have shown a concentration of 20-26% PMD is as effective as 15-20% DEET against mosquitos and ticks. PMD can provide up to 2 hours of protection against ticks and up to 5 hours against mosquitoes. However, like many insecticides, it should not be used in pregnant women or children under 3 years (Yates, 2015).
According to the CDC, natural tick repellants safe for skin include essential oils from lemongrass, rosemary, thyme, and geraniol plants, as well as 2-undecanone, an essential oil of tomatoes and cloves.
According to Reader's Digest, 4 ounces of distilled or boiled water, witch hazel, and 30-50 drops of cedar oil is effective; it's helpful to have a spray bottle handy.
Essential Oils Against Ticks: The Evidence
Studies have shown essential oils can also be effective against ticks without the adverse effects on the environment. However, their efficacy may not compare to DEET due to their volatility and low vapor pressure which causes them to evaporate from skin more quickly (Maia, 2011). As such, they may need to be applied more frequently, every hour, to stay effective.
Citronella and clove oil were as effective at repelling ticks as DEET (Thorsell, 2006)
A mixture of creeping thyme and citronella repelled 91% of ticks (Stefanidesova, 2017)
Oregano oil repelled ticks in vitro (Carroll, 2017)
Essential oils weren't as effective as DEET (Meng, 2016)
Geranium oil was found to be as effective as DEET (Tabanca, 2013)
Java citronella is has repellent, acaricidal, and larvicidal activity. Clove has acaricidal, antioxidant, anti-microbe, and antifungal properties and is widely used in dentistry (de Mello, 2014).
Killing Ticks: Pest Control
Studies have shown that the following essential oils may be effective at killing larva, nymphs, or adult ticks, altering oocyte morphology in female ticks, affecting egg-laying capacity (oviposition) or hatching, inhibiting reproduction of ticks, or reducing fertility in ticks. However, caution should be taken with acaricides, or tick killers, because they can promote pesticide resistance.
Tick life cycles last 3 years, and pest resistance is a problem with health and agricultural importance. Tick resistance to acaricides is growing with high intensity of use, starting from tropical and subtropical areas and spreading to the US (Rodriguez-Vivas, 2018).