Key to Reducing Ticks is Looking at Tick-Host Interactions Ticks, diseases, animals, humans, and the environment make up a complex web interactions. A vast majority of the tick life cycle is spent off the host, spread throughout the environment where they are hard to find and reach. This means acquiring a host and successfully feeding is a bottleneck in the tick lifecycle. Therefore, the main interactions we focus on at Tick Free MV are tick-host interactions, which fall into 3 main buckets: Reproductive hosts – animals on which ticks reproduce and complete their life cycle. This enables tick abundance or the total number of ticks out there. Dispersal hosts – since ticks largely do not move around in the environment on their own, animal hosts help ticks move around their environment. This enables ticks to spread to new areas. Reservoir hosts – animals that are infected with pathogens, that then infect the tick once it bites. After the tick drops off, it is now infectious to future hosts. This enables infectious disease transmission. There are animals that serve as multiple types of hosts. Deer definitively serve as 2 types of hosts (reproductive and dispersal hosts) and can serve as a third (reservoir host). Deer as Key Reproductive and Dispersal Hosts Deer are well-established in nationwide research as key reproductive and dispersal hosts for several tick species. Relevant to the Vineyard we will focus on how deer are central to deer tick and lone star tick abundance and spread. Deer are the largest warm-blooded animal on Martha’s Vineyard, they do not protect themselves from tick bites (unlike humans, pets, and livestock), and they walk through tick habitat every day picking up unfed ticks and dispersing fed ticks throughout the environment. To illustrate the impact of White-tailed deer on tick abundance, let’s review a couple numbers: Deer ticks were given that name for a reason. It has been estimated that over 90% of adult deer ticks feed on deer, find a mate, and then reproduce. Each adult female lays approximately 2,000 eggs (Stafford, 2009) Lone star ticks prefer large-bodied mammals, and here on the Vineyard that is deer. In one paper, at the peak season for Lone star tick (A. Americanum) density, researchers found an average of 200 adult ticks, 500 nymphs, and 1500 larvae on each White-tailed deer (Bloemer et al, 1988). Ticks only remain attached to a host for about a week before they drop off, so this is a snapshot of a peak week. Each adult lone star female can produce approximately 3,000 eggs. Home ranges for female deer (does) are 100 to 800 acres, while male deer can be as large as 400 to 2000 acres. As they range for food, shelter, and mating, they are picking up, feeding, and dropping off ticks in the environment. No other host species covers as great a range of territory, spreading ticks throughout the island. Deer as Occasional Reservoir Hosts Deer are known reservoir hosts for one pathogen found in Martha’s Vineyard lone star ticks: ehrlichia chafeensis (which causes ehrlichiosis). Deer do not serve as reservoir hosts for Lyme disease, babesiosis, anaplasmosis, or the other tickborne infections, but they still play a critical role as reproductive and dispersal hosts for ticks. Deer Reduction is a Necessary First Step, but not Sufficient on its own for Tick Borne Disease Reduction As outlined above, multiple public health and wildlife sources argue that substantially reducing deer density is a critical first step towards reducing tick numbers and thus bites and health risks. However, tickborne disease experts make clear that complementary strategies will be necessary to achieve the goal of reducing disease and suffering overall. This is often referred to as “Integrated Tick Management” or “Integrated Tick Control” where multiple strategies are employed to target ticks, hosts, diseases, and environment. Still, any intervention deployed will be swimming upstream against the extreme abundance of deer on Martha’s Vineyard. Therefore, deer reduction becomes a necessary first step. “Eradication of a zoonotic vector-borne disease is not possible without reducing the reproductive or pathogen reservoir host. One of the key insights gleaned from research is the existence of a White-tailed Deer density threshold for tick-borne disease transmission. When White-tailed Deer populations exceed certain thresholds, estimated at approximately 5–7 animals per km2 [equivalent to 13 to 18 deer per mi2], the risk of tick-borne diseases escalates significantly. This threshold serves as a crucial metric for wildlife managers and public health officials to implement effective strategies for disease control. By managing White-tailed Deer populations within or below these thresholds, communities can mitigate the risk of tick-borne diseases and safeguard public health. Reduction of White-tailed Deer densities could simultaneously address concerns over ecosystems, wildlife, and human health” Rochlin, I., Kenney, J., Little, E. et al. “Public health significance of the white‑tailed deer (Odocoileus virginianus) and its role in the eco‑epidemiology of tick and mosquito‑borne diseases in North America” Parasites Vectors 18, 43 (2025). https://doi.org/10.1186/s13071-025-06674-6 For the in-depth reader, we highly recommend reviewing the entire comprehensive article: “Public health significance of the white-tailed deer (Odocoileus virginianus) and its role in the eco-epidemiology of tick- and mosquito-borne diseases in North America” by Ilia Rochlin, Joan Kenney, Eliza Little, and Goudarz Molaei, published in Parasites & Vectors, 18:43, on Feb 6, 2025 

Before we go further, we should say that reducing ticks is hard to do. If this were easy, it would have been fixed already. Why? Ticks need a blood meal to grow into the next life stage, but they only need to get a blood meal 3 times in their whole lives. When they feed on hosts (animals or humans), they usually feed for 5-15 days before becoming fully engorged, and then drop off. Ticks live 2 or 3 years depending on the species, but they are only on hosts for a total of 15-45 days of their whole lives. This means for 95% of their lives, they are in the environment, not looking to bite, and spread across the landscape making targeted control efforts off of the host difficult. Different ticks like to be in different habitats and prefer to bite different animals. This is why it is essential that we not only look at host animals but also environmental strategies. Using multiple strategies to address ticks is often called “integrated tick control” or “integrated tick management.” All experts in the field of ticks state that a multi-pronged approach is necessary to address ticks. Islands also have the strongest chance of achieving and sustaining long-term tick reduction. 

The Martha’s Vineyard Tick Program and tick ecology researchers explicitly link these factors to our crisis: 1. Over-abundance of game species with the decline in hunting: Deer and turkey used to be hunted extensively for food. With fewer host animals, there were fewer ticks. Hunter numbers have declined progressively over decades as fewer people hunt for food, leaving hosts to proliferate. Humans have also removed large native carnivores (e.g. wolves) enabling unrestricted growth of prey populations throughout the region. 2. Tick abundance due to deer abundance: Vector abundance is linked to the abundance of their vertebrate hosts. White-tailed deer are key hosts for adult deer tick and Lone star tick reproduction cycles. The adult female deer tick are deer specialists, meaning she overwhelmingly prefers to take her last blood meal on a deer and the male adult finds her there to reproduce. Each female deer tick produces approximately 2,000 eggs while lone star tick females can produce 3,000 on average. For Lone star ticks, one study estimated that a single deer can harbor 200 adults, 500 nymphs, and 1,500 larvae during peak weeks of the season. Abundant deer provide ample opportunities for ticks to complete their reproduction cycle facilitating tick population growth. 3. Historical land use change made better habitat for hosts and ticks: Certain species of ticks have different habitat preferences ranging from open grasslands to dense forests. In the past 150 years the island environment has undergone drastic changes which affected habitat suitability to support certain tick species and their hosts. Overall, Martha’s Vineyard used to have mostly pastures and meadows, not forests. As agriculture dwindled as a main industry on the Vineyard, forests have reestablished creating more habitat suitable for deer ticks and lone star ticks as well as their associated hosts such as deer, turkey, mice, skunks and raccoons amplifying the abundance of both host and vector. 4. Suburban development and summer population growth: As Island habitats have changed, the increase of development in suburban and rural communities has exacerbated the issue. Increased development fragments continuous habitats creating edge habitat, also called ecotones, which provide increased forage and cover for common tick hosts perpetuating high tick abundances in areas of increased human density. The summer also brings more visitors to the island from April to September which coincides with peak tick activity season increasing contact between humans, vectors and the pathogens. This means more humans are getting bitten by more ticks. 5. Human activity: Our beautiful outdoors on Martha’s Vineyard is a large part of why people choose to live and visit here. However with our current tick problem, to go outside unprotected poses significant tick-bite risk. Increasingly, people are turning to effective personal protection strategies like permethrin-treated clothing, repellents, and covering up with long sleeves and pants. While there are effective and available ways to protect ourselves from tick bites, we dare to pursue a future where we can have picnics on the grass and a walk in the woods without requiring hypervigilance. 6. Globalization: Globalization increases the risk of invasive species—like the lone star tick or longhorned tick—finding new territories and becoming established. As people, pets, livestock, and goods move around the country and the world, invasive insects can hitch a ride. The lone star tick was found in established populations on Martha’s Vineyard in 2011 on Chappaquiddick. It is not known for sure how lone star ticks arrived on Martha’s Vineyard. One thought, is that they arrived on birds during migration. Another theory is they were introduced from travelling pets or animals coming from areas with abundant lone star ticks. Whether natural import, or unintentional import, once ticks find their way to the Vineyard they proliferate with our abundant host animals available. 7. Climate change: Our climate on Martha’s Vineyard is growing warmer and wetter. Ticks rely on warm, moist conditions for survival, but tolerances can depend on each species. Climate change could extend the season that ticks are actively looking for a bloodmeal. Greater opportunity to find a host will likely mean more success for ticks to grow to the next life stage.

Across all 6 towns, the Martha’s Vineyard Tick Program can find very high densities of: Deer ticks (Ixodes scapularis) – Also called the black-legged tick. Main vector for Lymedisease, babesiosis, anaplasmosis, Borrelia miyamotoi, and Powassan virus. Prefer moister, shady environments and can be found in leaf litter, low-lying grasses and vegetation, and where lawns meet the woods (edge habitat). Lone Star ticks (Amblyomma americanum) – Main vector for Alpha-gal Syndrome (an allergy to mammalian products). On Martha’s Vineyard, can carry infections like tularemia, ehrlichiosis and STARI. Elsewhere in the United States, can transmit Heartland virus and Bourbon Virus. These are heartier ticks and can be found in many Vineyard habitats. American Dog ticks (Dermecentor variablis) – Main vector for tularemia and Rocky Mountain Spotted Fever. Found in tall grasses like dune grasses and meadows. Longhorned Tick (Haemaphysalis longicornis) - As of 2026, longhorned ticks are rare but have been found on Martha’s Vineyard since 2023. In its native range in Asia, longhorned ticks can transmit diseases to humans. However, those diseases are not found in the United States. Therefore, the risk to humans is currently unknown, but there is potential for longhorned ticks to transmit pathogens. Longhorned ticks pose a threat to livestock and can transmit Theileriaorientalis Ikeda.

The Infectious Diseases: The Martha’s Vineyard Boards of Health provided public health surveillance data of infections in humans from 2020–2024 (per 100,000 population in Dukes County). Public health surveillance data accounts for residents and is put into context of the resident population to create a rate. They also included the comparison to the statewide rate provided by the Massachusetts Department of Public Health: Lyme: 784 confirmed and probable cases in five years, equating to a rate of 749.1 per 100,000 population (11 times state rate) Babesiosis: 113 confirmed and probable cases in five years, equating to a rate of 108.0 per 100,000 population (11 times state rate). Anaplasmosis: 60 confirmed and probable cases in five years, equating to a rate of 57.3 per 100,000 population (5 times state rate) Ehrlichiosis: 25 confirmed and probable cases in five years, equating to a rate of 23.9 per 100,000 population (99 times state rate) Rocky Mountain Spotted Fever: 22 confirmed and probable cases in five years, equating to a rate of 21.0 per 100,000 population (185 times state rate) Tularemia: 17 confirmed and probable cases in five years, equating to a rate of 16.2 per 100,000 population (143 times state rate) Powassan: One confirmed and probable case in five years, or a rate of 1.0 per 100,000 population (8 times state rate) Borrelia miyamotoi: 1 confirmed or probable case in five years, or a rate of 1.0 per 100,000 population (2 times state rate). The Allergy: Alpha-gal syndrome (AGS) is an allergy caused by the lone star tick bite. Elsewhere in the worldother species of ticks cause this allergy. Not everyone who is bitten develops the allergy, however for those who do, individuals can become allergic to mammal meat (e.g. beef, pork, venison, lamb), dairy, and/or medications containing mammal products (e.g. gelatin capsules, heparin, porcine heart valves, etc). The Martha’s Vineyard Tick Program has documented the rapid growth in size and distribution of the lone star tick. The growth in ticks has resulted in an allergy epidemic. Notably, the data on Alpha-gal syndrome is different than the data on infections. AGS is not a notifiable condition in Massachusetts (though it is in several other states). Public health officials, epidemiologists and Tick Free MV are advocating for the state to specifically record and track AGS testing and cases. In the interim, Martha’s Vineyard Hospital’s lab has provided data that shows a dramatic rise in total tests performed, and positive test results. Alpha Gal IgE Testing at Martha’s Vineyard Hospital: Year, Tests performed, Positive test results, Percent Positivity, 2020, 9, 2, 22.2% 2021, 78, 32, 41.0% 2022, 164, 77, 47.0% 2023, 382, 140, 36.6% 2024, 1254, 523, 41.7% 2025, 1689, 742, 43.9% Tests are not equal to cases. To be diagnosed with Alpha-gal syndrome requires both a positive test and allergic symptoms. It is possible for people to test positive for Alpha-gal IgE and not have allergic symptoms. This is called sensitization and is not Alpha-gal Syndrome. Public health officials do not know what proportion of these positive tests represent truly allergic individuals (cases) without detailed investigation. However, the data still tells us about trend. The dramatic rise in tests ordered shows increasing awareness and concern. Then the corresponding rise in the number of positive tests gives good indication of an increasing burden of allergic individuals. Nationally, CDC estimates that up to 450,000 of Americans may be living with AGS, particularly in the South and Mid-Atlantic where Lone Star ticks were historically concentrated. What makes Martha’s Vineyard unique is the rapid, exponential burden of allergy which matches the rapid, exponential expansion of Lone Star ticks. CDC’s Estimated Geographic distribution of suspected alpha-gal syndrome cases* per 1 million population per year — United States, 2017–2022 https://www.cdc.gov/mmwr/volumes/72/wr/mm7230a2.htm

Dogs, cats, horses, and livestock can get many of the same infections that humans can. Tickborne infections can cause severe symptoms in animals, especially if left untreated. On the Vineyard, there is a risk of a tick biting your animal all year round. Talk to your veterinarian about the best way to protect your animals from tick bites and tick-borne diseases. There is one tick problem that does not affect animals: Alpha-gal syndrome. Humans become allergic to Alpha-gal because our bodies do not have it naturally. All four-legged mammals have Alpha-gal in their cells and tissues, and they do not become allergic to themselves. For detailed information on tickborne diseases and the symptoms to look for in your pets, please visit: Veterinary Partner online.