Deer and Lyme Disease, Research and News on the Relationship

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Summary:  Deer are immune to Lyme disease and do not carry the disease. If an infected tick bites a deer, the disease does not spread to other ticks that may bite the deer as it would if the tick bit a mouse. Reducing the number of deer may reduce the number of ticks, but because of the dilution effect, the result can be a higher percentage of remaining ticks with the disease since the ticks will choose other hosts that may be carriers of the disease. Deer also browse on the vegetation that provide tick habitat. While deer may provide a meal for the adult tick, research shows the risk of Lyme disease is statistically correlated to mice, chipmunks, and ground dwelling birds. Deer groom themselves, eliminating many ticks.  A reference book

Ecology of Infection Disease:  A Special Report (On Lyme Disease) National Science Foundation

... Areas of patchy woods, which are very common in cities and suburban and rural areas, may have higher populations of Lyme-disease carrying ticks than forest fragments, which generally have fewer species than continuous habitat. This is because some species thrive in smaller places.  White-footed mice, for example, are more abundant in forest fragments in some parts of the country, likely because fewer predators and competitors remain there. These mice are particularly abundant in patches smaller than about five acres, which could spell trouble for people living nearby: the mice are the main carriers of Lyme disease-causing bacteria ... 

   "Our results suggest that efforts to reduce the risk of Lyme disease should be directed toward decreasing fragmentation of deciduous forests of the northeastern United States, particularly in areas with a high incidence of Lyme disease ...The creation of forest fragments smaller than five acres should especially be avoided."  

Lyme Disease, Deer management generally reduces densities of nymphal Ixodes scapularis, but not prevalence of infection with Borrelia burgdorferi sensu stricto 2023 - Ticks and Tick-borne Diseases

... Human Lyme disease–primarily caused by the bacterium Borrelia burgdorferi sensu stricto (s.s.) in North America–is the most common vector-borne disease in the United States ... Controlling white-tailed deer populations has been considered a potential method for reducing tick densities, as white-tailed deer are important hosts for blacklegged tick reproduction ... while white-tailed deer reduction efforts were followed by a decrease in the density of I. scapularis nymphs in parks, deer removal had variable effects on B. burgdorferi s.s. infection prevalence, with some parks experiencing slight declines and others slight increases in prevalence...

Experimental oral delivery of the systemic acaricide moxidectin to free-ranging white-tailed deer (Artiodactyla: Cervidae) parasitized by Amblyomma americanum (Ixodida: Ixodidae) 2023 Journal of Medical Entomology

... Orally delivered, host-targeted, systemic acaricide treatment has potential to be an effective areawide tick abatement strategy... While we did not document differences in burdens of parasitizing A. americanum based on moxidectin sera levels, we did document fewer engorged specimens on deer with increased sera levels. The systemic use of moxidectin for tick management in critical reproductive hosts has the potential to be effective in an areawide capacity while also permitting human consumption of treated venison...

Don't blame deer because ticks carry disease June 19, 2017 Maine, The Forecaster

"... Research in New England shows that when deer abundance is reduced, adult ticks crowd onto the remaining deer, so that there is little if any decline in total ticks on deer... Our studies in upstate New York show that Lyme disease risk is correlated with abundance of mice, but not with abundance of deer.  Deer do not infect the ticks with Lyme disease bacteria, but mice and chipmunks do..." [Dr. Richard Ostfeld, a director of The Tick Project]

An anti-Lyme disease vaccine for mice could help prevent human infections January 19, 2020 Connectictut, Medical Xpress

... Scientists at the Connecticut Agricultural Experiment Station recently finished a three-year study that provided vaccine-coated food pellets to mice in the backyards of 32 homes in Redding.  In a recently published paper on the study, researchers reported a 26% drop in the number of Lyme disease-infected white-footed mice ...

Tick expert: Killing deer, keeping chickens won't cut Lyme risk in Fayetteville May 26, 2016 New York, Syracuse Post-Standard

... Felicia Keesing, a Bard College biology professor who has researched the distribution of ticks and Lyme disease since 1999, said culling some deer hasn't been shown clearly to cut the risk of Lyme in communities. She said many of the studies that indicate culling deer could help have been found to be unreliable....

Where foxes thrive, Lyme disease doesn't September 10, 2012 New York, Poughkeepsie Journal

... Taal Levi has studied environments from Brazil to Alaska ... His statistical analysis showed little correlation between the prevalence of deer and the incidence of Lyme. If that were the case, Levi said, “then why is Lyme disease so relatively rare in Western New York when deer are more abundant than in places here that have lots of Lyme disease?” ...Levi used statistical data to show that as fox populations went down, Lyme went up. The statistical connection between Lyme and other species wasn’t as consistent. The study was published in the Proceedings of the National Academy of Sciences in June... 

Lyme study highlights why small mammals spread disease September 23, 2014 New York, Poughkeepsie Journal 

... The research also undercuts a misconception that Lyme disease is spread primarily by ticks that feed on deer, a notion that has incorrectly popularized the label "deer tick" for the black-legged tick that can be infected by other mammalian hosts...  large litters of mice, shrews and chipmunks correspond with the increased chance that a tick will pick up Lyme disease and two malaria-like diseases... [read the article in PLOS ONE]

State of New Hampshire Tickborne Disease Prevention Plan [PDF] March 31, 2015 

...   For the years 2008 and 2012, NH had the highest incidence rate of Lyme disease in the US.... Because NH is near the northern limit of white-tailed deer range it is known to have one of the lowest density deer herds in the eastern US ... The main, and shared, reservoir host for the four tickborne diseases known to be transmitted in NH is the white footed mouse. Chipmunks, shrews, voles and birds, including the American Robin, have also been identified as reservoirs for Lyme disease, although are of lesser importance. Wild

rodents have been identified as possible reservoirs for anaplasmosis and babesiosis; woodchucks, squirrels and the white footed mouse are the three known reservoirs for Powassan virus... 

Co-Infections Possible from Tick Bites June 24, 2014 Massachusetts,  Boston 

... New to this study, said co-author Felicia Keesing, is that the small mammals the ticks feed on also carry multiple infections... Ticks resort to feeding exclusively on small mammals when there aren’t larger animals, like raccoons or deer, to feast upon. ... scientists at Bard College, Sarah Lawrence College and the Cary Institute of Ecosystem Studies...

Have deer gotten a false rap for Lyme disease? August 3, 2012 Earthwise [includes pictures and podcast]

... While deer host lots of ticks, so do other vertebrates, including raccoons, skunks, and white-footed mice. Eliminate deer, and ticks will feed on other hosts. Also, while deer don’t transmit the Lyme bacterium to ticks—the smaller mammals do. Rick Ostfeld, a senior scientist at the Cary Institute of Ecosystem Studies, has written a book on Lyme disease ecology… 

Help Stop the Spread of Lyme Disease and Kill Deer Ticks With Damminix Tick Tubes August 22, 2013 Massachusetts, Comtex

... "Homeowners trying to kill ticks in their own yards need to target the rodents that carry the Lyme disease bacteria," says the CDC's Division of Vector-Borne Diseases Director Lyle Petersen in its recent report.  That's how Tick Tubes target deer ticks. Developed at the Harvard School of Public Health, Damminix relies on the natural nesting instincts of rodents that carry Lyme disease and is the only rodent-targeting deer tick control solution on the market today.  "Historically, people focused on deer as the culprit, but it's mice that spread Lyme disease," says Damminix Company Director Ariana Ganak. "When deer ticks hatch, they are disease free. Immature ticks feed on mice twice a year, and when they bite the infected mouse they become carriers of Lyme and pass it on to the unsuspecting general public. At long last people are becoming aware that mice are the real cause of this public health epidemic ...

     Spritzing deer with tick insecticide is one way to fight Lyme disease September 1, 2013 New Hampshire, Nashua Telegraph

...  the black-legged tick picks up the bacteria – a spirochete, to get technical – as a larva from the blood of the white-footed mouse, which carries the bacteria. ... They aren’t called “deer ticks” anymore ...  even if every deer in New Hampshire became tick-free, we could still get Lyme from ticks via the white-footed mouse...  the population of white-footed mice has exploded ... A variant of the deer feeding station idea is available for ticks: cardboard tubes filled with cotton balls treated with permethrin, a tick insecticide. Mice take the cotton back to their nests as building material, and it kills the ticks...

Forest Journal: Winter in New Hampshire a time for survival of the fittest January 18, 2014 New Hampshire, Union Leader 

... Deer don't experience severe winter tick infestations. They tend to groom off questing winter ticks in autumn...Overwintering deer ticks may be reduced by extreme cold. That good news translates into a reduction in future rates of human Lyme disease... 

East Hampton, Deer in Town Sights July 5, 2012 New York, East Hampton Star 

... As for Lyme disease, the Group for Wildlife suggests that the town do more to educate the public about how to avoid tick bites and to prohibit the hunting of turkeys, which eat immature ticks. Because Lyme disease is also spread by ticks that feed on the white-footed mouse, the report says, “it’s unlikely that any reduction of deer populations can alleviate the disease.” ... if deer were eliminated, the ticks would feed on other animals ... two recent studies show that “four-poster” stations, where deer are exposed to tick-killing chemicals, reduced ticks by 69 to 100 percent.... 

Hunting Isn’t the Answer to Animal “Pests” November 27, 2013, Time

... Efforts to reduce Lyme disease with deer hunting are ineffective because the ticks feed on a wide variety of host species ... The only places where hunting is effective are in isolated areas—islands and peninsulas–where the ticks have few alternate hosts. To reduce the incidence of Lyme disease in humans on the mainland, the number of ticks needs to be reduced, not the number of deer. A 2011 study published in Public Health Reports found that a tick-killing device led to a reduction in the incidence of Lyme disease in humans in the area, while deer hunting “did not show a clear decreasing trend.” ...

The Rocky Mountains Have Ticks. Scientists Want To Know What Viruses They're Carrying April 29, 2018 Colorado, KUNC

... Researchers in other parts of the country have noticed that when deer populations drop, Buttke says, “the following year and sometimes the next year we have a really, really high number of ticks looking for blood meal hosts.” Instead of biting deer, they turn to people. Buttke says it’s all speculation whether chronic wasting could lead to a temporary spike in tick-borne disease...

Tick expert: Killing deer, keeping chickens won't cut Lyme risk in Fayetteville May 26, 2016 New York

... Felicia Keesing, a Bard College biology professor who has researched the distribution of ticks and Lyme disease since 1999, said culling some deer hasn't been shown clearly to cut the risk of Lyme in communities. She said many of the studies that indicate culling deer could help have been found to be unreliable...

Missing Foxes Fuel Lyme Disease Spread June 18, 2012

Researchers used to think the increases were due to increasing deer populations ,,, However, the new data show these increases were independent of deer population levels... "Increases in Lyme disease in the Northeastern and Midwestern United States over the past three decades are frequently uncorrelated with deer abundance and instead coincide with a range-wide decline of a key small-mammal predator, the red fox, likely due to expansion of coyote populations,"... in the journal Proceedings of the National Academy of Sciences (June 18, 2012 article). 

Increase in Lyme disease cases might have a coyote connection July 8, 2012 Michigan, Detroit Free Press

... Increases in the deer population have been blamed for the explosion of Lyme disease cases, but changes in the numbers of foxes and coyotes -- and what they eat -- actually might be responsible, according to a study published late last month. ... As coyotes have expanded in numbers and range, the new study suggests, they interfere with the important role served by foxes: to suppress rodent hosts of Lyme disease, especially around human habitation.

Council Talks Deer Management, Chevy Chase Program Deemed A Success? February 28, 2013 Maryland, Bethesda Now

... County data shows the deer management program racked up 5,598 deer kills during the 2012-2013 seasons, 5,571 in 2011-2012, 5,969 in 2010-2011 and 5,599 in 2009-2010.  Despite those totals...      In the case of Lyme disease, which some dispute is related to deer overpopulation, the numbers have also remained steady. There were 297 confirmed and probably cases of Lyme disease in the county in 2011 and 296 in 2010, the two most recent years that those statistics were available.

Lyme Disease: Habitat Fragmentation and the Abundance of White-tailed Deer  L Chavez - 2017

... ​The results of the linear regressions that were ran did not support the hypothesis that in areas with increased cropland acreage there would be a higher population of white-tailed deer which would result in more reported cases of Lyme disease...

Surprise Culprits of Lyme Disease Boom June 18, 2012 Discovery News

Deer are not to blame for rising rates of Lyme disease ... Foxes don’t spread Lyme disease directly. Instead, they cull populations of small mammals, which are responsible for the bulk of infectious ticks. Where foxes are thriving, the risk of disease drops. But when fox numbers fall – often because coyotes move in, small mammal populations surge and Lyme disease flourishes. 

Killing deer is no solution [to Lyme Disease] September 17, 2013 Connecticut, The Advocate, Laura Simon

Preventing Lyme disease is a vital goal, but killing deer isn't a solution ... Even when deer numbers are drastically lowered, ticks have no trouble finding other hosts and reproducing merrily.... Mice and chipmunks are important hosts for the immature stages of the tick, and popular songbirds bring ticks to new areas... National health authorities, such as the Centers for Disease Control and World Health Authority, as well as Connecticut State Health Department, are not calling for increased hunting because it will not effectively reduce human disease risk...

Predators, Prey and Lyme Disease June 18, 2012 New York Times (blog)

... While people used to blame deer for the spread of Lyme disease, Dr. Levi said that scientific evidence has indicated that deer probably aren’t significant transmitters of B. burgdorferi bacteria because their systems tend to quickly flush it out. ... models showed higher numbers of Lyme disease cases in places where there are fewer foxes. They detected no significant relationship between numbers of deer and numbers of Lyme disease cases.

Deer, predators, and the emergence of Lyme disease Proceedings of the National Academy of Science. June 18, 2012. Taal Levi, A. Marm Kilpatrick, Marc Mangel, and Christopher C. Wilmers


Lyme disease is the most prevalent vector-borne disease in North America, and both the annual incidence and geographic range are increasing. The emergence of Lyme disease has been attributed to a century-long recovery of deer, an important reproductive host for adult ticks. However, a growing body of evidence suggests that Lyme disease risk may now be more dynamically linked to fluctuations in the abundance of small-mammal hosts that are thought to infect the majority of ticks. The continuing and rapid increase in Lyme disease over the past two decades, long after the recolonization of deer, suggests that other factors, including changes in the ecology of small-mammal hosts may be responsible for the continuing emergence of Lyme disease. We present a theoretical model that illustrates how reductions in small-mammal predators can sharply increase Lyme disease risk. We then show that increases in Lyme disease in the northeastern and midwestern United States over the past three decades are frequently uncorrelated with deer abundance and instead coincide with a range-wide decline of a key small-mammal predator, the red fox, likely due to expansion of coyote populations. Further, across four states we find poor spatial correlation between deer abundance and Lyme disease incidence, but coyote abundance and fox rarity effectively predict the spatial distribution of Lyme disease in New York. These results suggest that changes in predator communities may have cascading impacts that facilitate the emergence of zoonotic diseases, the vast majority of which rely on hosts that occupy low trophic levels.

Climate, Deer, Rodents, and Acorns as Determinants of Variation in Lyme-Disease Risk Ostfeld RS, Canham CD, Oggenfuss K, Winchcombe RJ, Keesing F (2006) Climate, Deer, Rodents, and Acorns as Determinants of Variation in Lyme-Disease Risk. PLoS Biol 4(6): e145. doi:10.1371/journal.pbio.0040145

Indices of deer abundance had no predictive power, and precipitation in the current year and temperature in the prior year had only weak effects on entomological risk. The strongest predictors of a current year's risk were the prior year's abundance of mice and chipmunks and abundance of acorns 2 y previously. In no case did inclusion of deer or climate variables improve the predictive power of models based on rodents, acorns, or both. We conclude that interannual variation in entomological risk of exposure to Lyme disease is correlated positively with prior abundance of key hosts for the immature stages of the tick vector and with critical food resources for those hosts.

Biodiversity and Disease Risk: The Case of Lyme Disease Richard S. Ostfeld and Felicia Keesing

Conservation Biology Vol. 14, No. 3 (Jun., 2000), pp. 722-728

"A positive correlation between Lyme disease per capita and species richness of ground dwelling birds . . ."

Full Abstract: Utilitarian arguments concerning the value of biodiversity often include the benefits of animals, plants, and microbes as sources of medicines and as laboratory models of disease. The concept that species diversity per se may influence risk of exposure to disease has not been well developed, however. We present a conceptual model of how high species richness and evenness in communities of terrestrial vertebrates may reduce risk of exposure to Lyme disease, a spirochetal (Borrelia burgdorferi) disease transmitted by ixodid tick vectors. Many ticks never become infected because some hosts are highly inefficient at transmitting spirochete infections to feeding ti cks. In North America, the most competent reservoir host for the Lyme disease agent is the white-footed mouse (Peromyscus leucopus), a species that is widespread and locally abundant. We suggest that increases in species diversity within host communities may dilute the power of white-footed mice to infect ticks by causing more ticks to feed on inefficient disease reservoirs. High species diversity therefore is expected to result in lower prevalence of infection in ticks and consequently in lower risk of human exposure to Lyme disease. Analyses of states and multistate regions along the east coast of the United States demonstrated significant negative correlations between species richness of terrestrial small mammals (orders Rodentia, Insectivora, and Lagomorpha), a key group of hosts for ticks, and per capita numbers of reported Lyme disease cases, which supports our "dilution effect" hypothesis. We contrasted these findings to what might be expected when vectors acquire disease agents efficiently from many hosts, in which case infection prevalence of ticks may increase with increasing diversity hosts. A positive correlation between per capita Lyme disease cases and species richness of ground-dwelling birds supported this hypothesis, which we call the "rescue effect." The reservoir competence of hosts within vertebrate communities and the degree of specialization by ticks on particular hosts will strongly influence the relationship between species diversity and the risk of exposure to the many vector-borne diseases that plague humans.

Dilution Effect, "the scientific evidence as I’ve reviewed it, without any preconceived notion or political agenda or any other agenda, does not support the notion that tick numbers and Lyme disease risk are strongly correlated with deer numbers, and the data do not suggest that if you manage deer by hunting, you’ll reduce the number of Lyme cases.” Dr. Richard S. Ostfeld Disease Ecologist Ph.D., 1985, University of California. Buy the book on Amazon: Lyme Disease: The Ecology of a Complex System

Acorns And Mice Driving Unusual Lyme Disease Risks (ICEID 2) March 14, 2012, Wired News

Dr. Richard S. Ostfeld of the Cary Institute of Ecosystem Studies in Millbrook, New York, explained .. Mice also can survive in much smaller areas than the larger animals, chiefly deer, that are usually blamed for perpetuating Lyme, Ostfeld pointed out. In sampling of “forest fragments” sliced up by development in three northeastern states, his team has not found a parcel in which mice did not thrive. Larger parcels with more balanced ecosystems, with natural mouse predators and larger mammals, actually tend to have lower Lyme density ...

White-tailed deer live throughout Minnesota, but blacklegged ticks are not found everywhere that deer live

From Michigan Department of Natural Resources (Lyme disease): The relationship between deer and the disease is complex. Deer show no symptoms of the disease. Deer may carry small numbers of the spirochete that causes Lyme disease but they are dead-end hosts for the bacterium. Deer cannot infect another animal directly and no deer hunter has acquired the disease from dressing out a deer. Infected ticks that drop from deer present little risk to humans or other animals since the ticks are now at the end of their life cycle and will not feed again. There is no evidence that humans can become infected by eating venison from an infected deer. In addition, the Lyme organism is killed by the high temperatures that would be reached when venison is cooked or smoked. Deer supply the tick that transmits the bacterium with a place to mate and provides a blood meal for the female tick prior to production of eggs. Research has shown that white-tailed deer are important to the reproductive success of the black-legged tick. In the absence of deer, this tick will opportunistically feed on other medium sized mammals and humans. As a management tool for Lyme Disease, there is still debate in the scientific community as to whether reducing the number of deer present in an area will effectively or dramatically reduce Lyme Disease "risk".

Duke Forest, Our illogical war on deer February 9, 2013 North Carolina, The Durham News, Karin Yates

...   According to John Rohm of the Virginia Department of Game and Inland Fisheries, “Reducing deer density by X will not = X percentage reduction in Lyme disease cases. ... Deer should not be blamed for the current Lyme disease situation. Integrated pest management would be more effective than focusing solely on deer.”

Deer ticks thriving in Ohio December 3, 2013

... “Migratory birds probably brought them to Ohio from Pennsylvania,” Needham said [Glen Needham, Ph. D., a deer tick expert and associate professor emeritus at Ohio State University] ... “Deer ticks will feed on anything despite their name,” ..

Studies confirm lizards fight Lyme disease May 30, 2015 California, Tehachapi News

... Western Fence Lizards, more commonly known as “Bluebellies,” ... Bluebellies eat ticks, which reduces the numbers of these parasites, but they also do something more extraordinary: a protein in the blood of Western Fence Lizards kills the Lyme disease bacterium in ticks that feed on the lizards ... Professor Jeff Burkhart of the University of La Verne ...

Explanation for Chronic Lyme Disease

Does this new study put an end to the chronic Lyme Disease controversy? Allentown Morning Call   November 16, 2012 

... It's not one stubborn infection that is making them ill, states a study released this week by the New England Journal of Medicine, but multiple new infections.  Researchers at the University of Pennsylvania and New York Medical College studied 17 patients, who had the classic erythema migrans rash associated with Lyme disease, more than once in a span of 20 years. They analyzed the genetic makeup of the Lyme-causing bacteria in those who had been sick several times. Each time, they were infected by different strains of the bacteria, ruling out relapses.

Crucial Player For Lyme Disease Transmission Identified Decenber 21, 2013 RedOrbit

... Borrelia burgdorferi, the bacterium that causes Lyme disease, hitchhikes in ticks for dissemination to mammalian hosts–including humans. An article in the 19 December issue of PLOS Pathogens identifies HrpA, an RNA helicase, as a crucial player in the transmission from ticks to mammals... The authors say, “We now know that HrpA is involved in both parts of the B. burgdorferi lifecycle: animal infection and tick transmission, making it a very important protein in B. burgdorferi gene regulation and establishing gene regulation through an RNA helicase as an important regulatory pathway in the Lyme spirochete.”

Other Motives for the Lyme Disease Hunts

Odgen Dunes, Deer Management Task Force Publishes Findings/Opinions July 12, 2012 Indiana, SaveOurDeer.Org

... Ogden Dunes has not come to a consensus on whether there is an overabundance of deer in Ogden Dunes. But they have come to a consensus that killing deer will not eliminate the risk of Lyme Disease ... Despite this development, the threat of a deer cull within Town limits seems to remain. Why? ... It appears the real reason for the deer cull was never to protect young families from the risk of Lyme Disease. The Town government was using the fear factor of Lyme Disease to promote the idea of a deer cull when the real reason was to kill deer to keep them from eating the plants of prominent town residents... 

Moose Die-Off Alarms Scientists October 14, 2013 New York, New York Times

... Across North America ... moose populations are in steep decline. And no one is sure why... Minnesota had two geographically separate moose populations. One of them has virtually disappeared since the 1990s, declining to fewer than 100 from 4,000... In New Hampshire, a longer fall with less snow has greatly increased the number of winter ticks, a devastating parasite... Deer are grooming animals, so they are able to keep tick numbers fairly low ...

Some Contradictory Results from Connecticut, based on Insular Enivronments

The Relationship Between Deer Density, Tick Abundance, and Human Cases of Lyme Disease in a Residential Community  Journal of Medical Entomology, Howard J. Kilpatrick,1,2 Andrew M. Labonte,1 and Kirby C. Stafford, III3

... Reducing deer density to 5.1 deer per square kilometer resulted in a 76% reduction in tick abundance, 70% reduction in the entomological risk index, and 80% reduction in resident-reported cases of Lyme disease in the community from before to after a hunt was initiated... [This study shows a short term reduction but it was done one a pennisula with limited other animals.  This relationship has only been documented on insular environments, not in open environments]  ... from page 778 of the article:  "The study area was the Mumford Cove (MC; 80.9-ha) community in Groton, CT. The number of occupied residences in MC year-round varied from 98 to 119 during the study. House lots were 0.61 ha each.  MC was situated on a 1.9-km2 coastal peninsula bordered by Long Island Sound to the east and west.  North of the peninsula was an 80-ha undeveloped state park closed to hunting and separated from MC by a

1.83-m-high chain-link fence. South of MC was the 105.9-ha residential community of Groton Long Point..."

Jamestown, Deer cull is counterproductive, says opponents September 11, 2014 Rhode Island, The Jamestown Press 

... what about Monhegan Island off the coast of Maine? Professional sharpshooters eliminated the deer there in the 1990s, and the Lyme disappeared...  Monhegan Island does not have mice. “It’s a whole different host ecology,” [Laura Simon] said. To compare Monhegan Island to Jamestown would be “like apples and bananas.” ...

The use of deer vehicle accidents as a proxy for measuring the degree of interaction between human and deer populations and its correlation with the incidence rate of Lyme disease.  DH Wiznia, PJ Christos, AM LaBonte - Journal of environmental health, 2013

... The authors also examined the relationship between deer population density and human Lyme incidence rate. They analyzed data from Connecticut's Department of Environmental Protection and the Department of Public Health from 1999 through 2008 by deer management zone (DMZ) and town. For DVA incidence rate versus Lyme incidence rate for both DMZs and towns, most of the correlation coefficients computed yearly were moderate to strong and all of the p-values were significant. A weak correlation was observed between deer population density and Lyme disease incidence rate by DMZ. The authors propose DVAs as a proxy for measuring the interaction between coexisting populations of humans and deer.

Long-Term Effects of Berberis thunbergii (Ranunculales: Berberidaceae) Management on Ixodes scapularis (Acari: Ixodidae) Abundance and Borrelia burgdorferi SC Williams, MA Linske, JS Ward - Environmental Entomology, 2017

... Barberry management reduced B. burgdorferi-infected adult I. scapularis (BBIAIS) abundances (191/ha ± 64 SE) over 6 yr to statistically indifferent from that of no barberry areas (140/ha ± 47 SE; P = 0.080) and significantly less than intact barberry stands (458/ha ± 80 SE; P = 0.026). Over 9 yr, BBIAIS abundances in managed barberry remained lower than intact barberry stands (P = 0.037), but increased to be significantly greater than no barberry areas (P = 0.007) as cover increased over time. Longer-term data further document that Japanese barberry infestations are favorable habitat for I. scapularis...

Integrated Control of Nymphal Ixodes scapularis: Effectiveness of White-Tailed Deer Reduction, the Entomopathogenic Fungus Metarhizium anisopliae, and Fipronil … SC Williams, KC Stafford III, G Molaei, MA Linske - Vector-Borne and Zoonotic …, 2017

… Unfortunately, the efficacy of deer reduction as a tick management strategy in noninsular settings still remains unclear (Kugeler et al. 2016) ... questions related to the data analysis are presented in this link

Deer-Free Areas May Be Haven For Ticks, Disease

... This ScienceDaily article summarizes a Penn State Study: "This goes somewhat against conventional wisdom. When you remove deer, it does not always reduce the tick population," says Perkins. "If you were to exclude deer from hundreds of acres, tick numbers will fall. But in an area less than 2.5 acres, you are more likely to increase tick density and probably create tick-borne hotspots." ...

An Army Of Deer Ticks Carrying Lyme Disease Is Advancing And Here's Why It Will Only Get Worse August 7, 2018 HuffPost

... Rebecca Eisen, a federal CDC biologist who has studied climate’s influenceon Lyme, notes that deer ticks dominated the East Coast until the 1800s, when forests gave way to fields. The transition nearly wiped out the tick, which thrives in the leaf litter of oaks and maples. Since the 1990s, a decline in agriculture has brought back forests while suburbia has sprawled to the woods’ edges, creating the perfect habitat for tick hosts.  Eisen suspects this changing land-use pattern is behind Lyme’s spread in mid-Atlantic states like Pennsylvania ...

Lake Michigan insights from island studies: the roles of chipmunks and coyotes in maintaining Ixodes scapularis and Borrelia burgdorferi in the absence of white-tailed deer

2021 Ticks and Tick-borne

... deer herd exists on North Manitou Island but not on South Manitou Island, where coyotes (Canis latrans) and hares (Sylvilagus lepus) are the dominant medium mammals... Our investigation demonstrated that alternative hosts could maintain a local population of blacklegged ticks and an enzootic cycle of the Lyme disease bacterium in the absence of white-tailed deer...


Effects of Reduced Deer Density on the Abundance of Ixodes scapularis

(Acari: Ixodidae) and Lyme Disease Incidence in a Northern

New Jersey Endemic Area



Freehold Area Health Department, 1 Municipal Plaza, Freehold, NJ


J. Med. Entomol. 44(5): 752Ð757 (2007)

ABSTRACT We monitored the abundance of Ixodes scapularis Say (Acari: Ixodidae) and the Lyme disease incidence rate after the incremental removal of white-tailed deer, Odocoileus virginianus Zimmermann, within a suburban residential area to determine whether there was a measurable decrease in the abundance of ticks due to deer removal and whether the reduction in ticks resulted in a reduction in the incidence rate within the human population. After three seasons, the estimated deer population was reduced by 46.7%, from the 2002 postfawning estimate of 2,899 deer (45.6 deer per km2) to a 2005 estimate of 1,540 deer (24.3 deer per km2). There was no apparent effect of the deer culling program on numbers of questing I. scapularis subadults in the culling areas, and the overall numbers of host-seeking ticks in the culling areas seemed to increase in the second year of the program. The Lyme disease incidence rate generated by both passive and active surveillance systems showed no clear trend among years, and it did not seem to vary with declining deer density. Given the resources required to mount and maintain a community-based program of sufficient magnitude to effectively reduce vector tick density in ecologically open situations where there are fe impediments to deer movement, it may be that deer reduction, although serving other community goals, is unlikely to be a primary means of tick control by itself. However, in concert with other tick control interventions, such programs may provide one aspect of a successful community effort to reduce the abundance of vector ticks.

Overpopulation problems December 20, 2010 Part 2 of 3 The Adirondack Daily Enterprise

Biologists Felicia Keesing and Richard Ostfeld reject the tick-Lyme disease connection, noting that studies in New York and New Jersey found no correlation between the number of deer and the number of ticks in a region. These researchers argue that when deer are scarce, ticks simply move to alternate hosts: raccoons, skunks, opossums and other medium sized animals. Keesing and Ostfeld note that Lyme disease is rare in Southeastern and most Midwestern states, regions of the country where deer are plentiful.

UMaine and Maine Medical Center study illustrates how Lyme disease-causing ticks have increased in Maine March 30, 2022 Bangor Daily News

... one small mammal in the study rose above the rest when it came to carrying blacklegged ticks... White-footed mice hosted just over 94% of all the blacklegged ticks found, and 15% of all white-footed mice had blacklegged ticks on them... The study was published in the Journal of Medical Entomology in December

Youtube Video:  A young Mule Deer in Colorado Springs get help from a flock of Magpies who are eating parasites off his back.

A Contradictory Study:  Information about problems with this study

The relationship between deer density, tick abundance, and human cases of Lyme disease in a residential community.  Kilpatrick HJ, LaBonte AM, Stafford KC.

... After hunts were initiated, number and frequency of deer observations in the community were greatly reduced as were resident-reported cases of Lyme disease. Number of resident-reported cases of Lyme disease per 100 households was strongly correlated to deer density in the community. Reducing deer density to 5.1 deer per square kilometer resulted in a 76% reduction in tick abundance, 70% reduction in the entomological risk index, and 80% reduction in resident-reported cases of Lyme disease in the community from before to after a hunt was initiated.  

In some news articles Dr Fish, a Lyme Researcher, associates Lyme Disease and Deer without research support.  Explanation

Misinformation from USDA

Long Island, 2014 East End Deer Damage Management Report  August 2014 New York, Prepared by: United States Department of Agriculture Animal and Plant Health Inspection Service Wildlife Service

... White-tailed deer are a vector of several prevalent and serious tick borne diseases on the East End of Long Island, including Lyme disease ... [White-tail deer are not a vector for Lyme disease. They are immune to Lyme and do not transmit the disease.]

Information about the 4-poster System and Ivermectin Used to Control Ticks on Deer

Acceptability of 4-poster deer treatment devices for community-wide tick control among residents of high Lyme disease incidence counties in Connecticut and New York, USA - Ticks and Tick-born Diseases, 2023

...  to understand perceptions and experiences related to tickborne diseases, support or concerns for placement of 4-poster devices in their community, and opinions on which entities should be responsible for tick control on private properties. Overall, 37% of 1652 respondents (5.5% response rate) would support placement of a 4-poster device on their own property, 71% would support placement on other private land in their community, and 90% would support placement on public land...

Tick prevention and deer populations: Unraveling the Lyme Disease conundrum September 28, 2023 New York, CNY Central

... Quirion said deer culling is an effective strategy for limiting the population of deer. However, according to Royal Scuderi, the Executive Director of the CNY Lyme & Tick-Borne Disease Alliance, deer culling won't decrease the amount of ticks in an area.  "In an area like this where they (deer) are roaming freely and breeding freely, you're never going to be able to cull them down to a manageable amount that has any kind of impact," said Scuderi.

Ivermectin May Be Good for Humans After All—Indirectly July 27, 2023 Connecticut, Mother Jones

... In a small study, they found that feeding deer corn dosed with an ivermectin derivative builds up enough drug in their blood that ticks biting them will (probably) die... “This was a proof-of-concept study,” says lead author Scott Williams, a wildlife ecologist and chief scientist at the Connecticut Agricultural Experiment Station in New Haven...

Host-utilization differences between larval and nymphal deer ticks in northeastern US sites enzootic for Borrelia burgdorferi sensu stricto

HK Goethert, TN Mather, A O'Callahan, SR Telford III - Ticks and Tick-borne Diseases, 2023

... Both stages of ticks were less likely to be infected if they had fed on deer (OR=0.08 [] and OR=0.4 [0.2,0.7] tested as nymphs and adults, respectively) and thus deer likely served to reduce the force of transmission at our sites...

White-tailed deer blood shown to kill bacteria that causes Lyme disease March 30, 2023 Massachusetts,

... The study, published recently in the journal Vector-borne and Zoonotic Diseases, demonstrates that the blood of the white-tailed deer kills the corkscrew-shaped bacterium that causes Lyme disease, a potentially debilitating illness... "We've known for some time that ticks taken from white-tailed deer are not infected ... [study below]

Development of a low-dose fipronil deer feed: evaluation of efficacy against two medically important tick species parasitizing white-tailed deer (Odocoileus virginianus) under pen conditions March 9, 2023 Parasites & Vectors - BioMed Central

... The fipronil deer feed efficaciously controlled ticks parasitizing pen-reared white-tailed deer. Efficacy in reducing survivorship of blood-feeding female I. scapularis exceeded 90% in all instances except for when ticks parasitized 48-h treated deer at day 21 post-exposure (47.2%). Efficacy in reducing survivorship of A. americanum females exceeded 80% in all instances. In the 120-h exposure group there was 100% tick mortality at day 7 post-exposure for both tick species...

White-Tailed Deer Serum Kills the Lyme Disease Spirochete, Borrelia burgdorferi 2023 Vector-Borne and Zoonotic Diseases

...  White-tailed deer (WTD) are considered to be noncompetent reservoirs for B. burgdorferi... we demonstrated that WTD serum effectively kills B. burgdorferi. The borreliacidal activity of WTD serum likely contributes to the inability of WTD to efficiently harbor and transmit B. burgdorferi...

Bugged Out: Just How Much Should We Worry About Ticks in Rhode Island? October 19, 2022 Rhode Island Monthly

...  URI, a participant in a new $10 million CDC regional grant to fund a New England Center of Excellence in Vector-Borne Diseases, is exploring the development of a deer-ingestible tick repellent and killer, similar to those for dogs and cats... 

Supplemental feeding of deer reduces tick abundance in Mississippi, USA.  2022. Journal of Vector Ecology, 2022

... Supplemental deer feeding appears to influence ticks, possibly due to decreased tick habitat and increased wildlife use around feeders. Our findings indicate feeding does not lead to increased prevalence of Ehrlichia or Rickettsia bacteria within A. americanum locally...

As New England winters warm, moose are getting overwhelmed by winter ticks. Some scientists say hunting could help March 29, 2022 Vermont Public Radio

... in Vermont and elsewhere in Northern New England, shorter winters with less snow mean the ticks now pose a bigger threat to moose than they did in the past... Unlike white-tailed deer, moose are poor groomers. As a result, a single animal can carry as many as 90,000 ticks through the season...

Invasive Plants Have RI's Native Life in Stranglehold January 22, 2022 Rhode Island, ecoRI News

... Japanese barberry ... used in residential and commercial landscapes because of its fall coloring and deer resistance. But the prickly shrub easily spreads into woodlands ... research in 2011 found that barberry-infested forests are about 12 times more likely to harbor deer ticks than forests without barberry...

The effects of year-round supplemental feeding of white-tailed deer on sources of disease

2021 Mississippi State University

... feeding reduced the number of ticks at feeder sites, but did not alter the prevalence of tick-borne diseases within captured ticks compared to sites without feeders...

Deer are not the only mammals to blame for Lyme disease May 11, 2021 New York, Times Union

... “There are some scientists who think that the abundance of deer is the most important factor determining the abundance of ticks later on,” said Ostfeld. “We don't find that in our studies. Over 30 years, in the Hudson Valley, we do not find a signal from the deer population, but we do find a strong signal from the mouse population,” ...

Control of tick infestations in wild roe deer (Capreolus capreolus) vaccinated with the Q38 Subolesin/Akirin chimera M Contreras, C San José, A Estrada-Peña, V Talavera… - Vaccine, 2020

... Vaccination with Q38 chimera controls multiple tick species that can be found on the same host...  Q38 showed efficacy by reducing tick populations in field conditions.  Results support Q38 as a candidate universal antigen to control multiple tick species...

Game commission: Reducing deer population not likely to stem spread of Lyme disease December 18, 2019 Pennsylvania, TribLIVE

... “There have been studies in New England where they’ve reduced the deer population and not found a change in Lyme transmission or its occurrence in small mammals,” ...

Research from Mississippi State University finds fewer ticks around deer feeders because the feeders attract animals that eat the ticks such as bird and the great trick predator, the opossum

Deer don't get Lyme April 16, 2019 Massachusetts, Martha's Vineyard Times

...  a scientific paper  ... research she and fellow scientists conducted on Block Island concluded white-tailed deer play a role in lowering the prevalence of Lyme (Borrelia burgdorferi) infection in black-legged tick nymphs... may call into question the utility of deer culling... “The blood in the deer actively kills the borrelia in the tick as it feeds,” [Columbia University eco-epidemiologist Maria Diuk-Wasser] ...

Lyme-disease research in Howard County seeks best ways to reduce tick populations October 4, 2018 Maryland, Washington Post

... Contrary to the popular belief that deer are the primary source of the disease spread by ticks, researchers say, it is mice that usually first infect young ticks with the bacteria that causes Lyme... using a device for deer, called a “four poster,” that attracts deer with bait.,, except that it carries a pesticide to kill ticks...

Staten Island, City spending $600000 to fight ticks, Lyme April 7, 2019 New York,

... funding is going after the Island’s mice, rather than deer, which experts have said has played a significant role in the spread of Lyme in the borough... will buy $25 bait boxes that will trap mice ... [four poster] stations are too expensive to maintain and that only some studies have shown the stations can reduce tick populations...

Tick‐borne disease risk in a forest food web May, 2018 Ecology, Richard S. Ostfeld  Taal Levi  Felicia Keesing  Kelly Oggenfuss  Charles D. Canham

... use 19 yr of data from six large field plots in southeastern New York to compare the effects of hypothesized drivers of interannual variation in Lyme disease risk, including the abundance of acorns, rodents, and deer, as well as a series of climate variables ... Acorn‐driven increases in the abundance of mice were correlated with a lagged increase in the abundance of questing nymph‐stage Ixodes scapularis ticks infected with Lyme disease bacteria. Abundance of white‐tailed deer 2 yr prior also correlated with increased density of infected nymphal ticks, although the effect was weak...  

Forest ecosystem influences tick-borne disease risk in the eastern US July 10, 2018 News Medical

... In the eastern US, risk of contracting Lyme disease is higher in fragmented forests with high rodent densities and low numbers of resident fox, opossum, and raccoons. These are among the findings from an analysis of 19 years of data on the ecology of tick-borne disease in a forested landscape, recently published in the journal Ecology [link to article above]...

Will Culling White‐Tailed Deer Prevent Lyme Disease? KJ Kugeler, RA Jordan, TL Schulze, KS Griffith… - Zoonoses and Public Health, 2015

... Elimination of deer from islands and other isolated settings can have a substantial impact on the reproduction of blacklegged ticks, while reduction short of complete elimination has yielded mixed results. To date, most studies have been conducted in ecologic situations that are not representative to the vast majority of areas with high human Lyme disease risk. Robust evidence linking deer control to reduced human Lyme disease risk is lacking. Currently, there is insufficient evidence to recommend deer population reduction as a Lyme disease prevention measure, except in specific ecologic circumstances. [island environments]

Experts say mice are primary cause of Lyme disease, not deer October 31, 2017 New York, The Daily Orange

... Phillip Baker, executive director at the American Lyme Disease Foundation, said there is a misconception of deer being the main transmitters of tick-borne illnesses. Baker said mice and other small rodents are the main organisms that keep the diseases percolating in the area where they are introduced...

Evaluating the effectiveness of an integrated tick management approach on multiple pathogen infection in Ixodes scapularis questing nymphs and larvae parasitizing …   EAH Little, SC Williams, KC Stafford, MA Linske… - Experimental and Applied …, 2019

... Compared to the control treatment, the odds of collecting a parasitizing I. scapularis infected with any pathogen from a white-footed mouse (Peromyscus leucopus) was reduced by 90% in the combined deer removal, Met52, and fipronil rodent bait box treatment and by 93% in the Met52 and fipronil rodent bait box treatment combination... [Note that in this study treatment including removal of deer removed reduced pathogens by less than when deer were not removed]

Mice Against Ticks: an experimental community-guided effort to prevent tick-borne disease by altering the shared environment

J Buchthal, SW Evans, J Lunshof, SR Telford III… - … Transactions of the Royal Society B, 2019

...Mice Against Ticks is a community-guided ecological engineering project that aims to prevent tick-borne disease by using CRISPR-based genome editing to heritably immunize the white-footed mice (Peromyscus leucopus) responsible for infecting many ticks in eastern North America... 

Popular plant causing problems August 2, 2018 Maine, WABI

... "It is shown in multiple studies that when you have Japanese barberry thickets, that you're going to have as much as 90% more ticks in those areas, and they're much more infected as well, with either lyme disease or antiplasma or babesiosis,"...

Ticks make you nervous? You need more coyotes August 17, 2017  Port Huron Times Herald

... R. Hofmeester, at Wageningen University in the Netherlands ... areas with high numbers of foxes and martens, a predator in the weasel family, would have fewer mice and fewer infected ticks ... Nervous mice tend to stay home. Mice that stay home don’t run into ticks, don’t provide food for the next generation of ticks and don’t become infected with Lyme disease  ... nothing else — culling deer, killing mice, spraying pesticides — has had an effect on tick numbers or tick-borne diseases that comes even close to Hofmeester’s findings... [coyotes reduce fox populations]

Impact of whitetailed deer on the spread of Borrelia burgdorferi  AL FEGHALI - Medical and veterinary entomology, 2017

... the causative agent of Lyme disease, Borrelia burgdorferi. This study examines the pathogen prevalence rate of Borrelia in adult Ixodes scapularis (Ixodida: Ixodidae), the blacklegged tick, collected from whitetailed deer and compares it with pathogen prevalence rates in adult ticks gathered by dragging vegetation in two contiguous counties west of the Hudson Valley in upstate New York. In both Broome and Chenango Counties, attached and unattached ticks harvested from whitetailed deer had significantly lower prevalences of B.burgdorferi than those collected from vegetation. No attached ticks on deer (n=48) in either county, and only 2.4 and 7.3% of unattached ticks (n=389) in Broome and Chenango Counties, respectively, were harbouring the pathogen. This contrasts with the finding that 40.8% of ticks in Broome County and 46.8% of ticks in Chenango County collected from vegetation harboured the pathogen. These data suggest that a mechanism in whitetailed deer may aid in clearing the pathogen from attached deer ticks ...

Oh deer, what should we do? Addressing the suburban deer dilemma August 3, 2017 Virginia, Washington Post

...  a linear relationship has not been established between deer population density and the abundance of the disease... Kevin R. Rose, a district wildlife biologist at the Virginia Department of Game and Inland Fisheries (VDGIF)

What's to blame for the surge in Lyme disease? March 28, 2017 Pennsylvania, Pittsburgh Post-Gazette

... Don’t blame deer. They now may be off the hook as the main vectors of the infectious disease.  Instead, most scientists and publications point to the expected overpopulation of white-footed mice this year as the reason Lyme disease incidence ...

Why One Plant May Be Fueling the Spread of Lyme Disease October 20, 2017 NBC New York

... an acre of forest containing Japanese barberry averages a Lyme disease-carrying tick population 12 times higher than an acre with no barberry...  [Dr. Scott Williams, the lead researcher on Japanese barberry for the Connecticut Agricultural Experiment Station (CAES)]

A plague of ticks: scientists search for solutions September 15, 2017 New York, Bennington Banner

... The larvae may become infected with the bacterium that causes Lyme disease through this blood meal; it all depends on what kind of animal they find as a host. If it's a white-footed mouse, they're very likely to contract the Lyme spirochete. If it's a chipmunk or shrew, they're somewhat likely. If it's a squirrel or a larger mammal [deer], they probably won't...

The battle aqainst bloodsuckers begins July 23, 2017 Massachusetts, 

MetroWest Daily News

... despite the name “deer tick,” ticks rely relatively heavily on mice ... ticks will survive on any mammal.  “Deer get picked on because they named it the deer tick,” Weston Public Health Director Wendy Diotalevi said. “If you took out every deer in all of New England, that tick would survive because it would become the raccoon tick, or the bunny tick.” ... don’t expect hunting to put any noticeable dent in ... the associated Lyme disease cases...

Use natural biodiversity to fight Lyme disease January 3, 2017 Pennsylvania, Scranton Times-Tribune

... years of studies couldn’t reliably correlate deer numbers and Lyme disease. Indeed, only a tiny fraction of the ticks on deer became infected with the bacterium that causes Lyme... [Ostfeld and his colleagues at the Cary Institute of Ecosystem Studies] ... forests fragmented and otherwise disrupted by humans clearly favor those mammals that are better Lyme transmitters...

Heterogeneity in the abundance and distribution of Ixodes ricinus and Borrelia burgdorferi (sensu lato) in Scotland: implications for risk prediction  C Millins, L Gilbert, P Johnson, M James, E Kilbride… - Parasites & Vectors, 2016

... Cases of Lyme borreliosis, a vector-borne zoonosis caused by bacteria in the Borrelia burgdorferi (sensu lato) species group, have increased in recent years in Europe  ... A higher prevalence of B. burgdorferi (s.l.), higher densities of nymphs and higher densities of infected nymphs were found at sites with warmer climates, estimated with growing degree-days. No association between infection prevalence in nymphs and woodland type (semi-natural mixed vs coniferous) or deer density was found. At six sites sampled in 2012 and 2013, there was a significant increase in B. afzelli prevalence at two sites and a decrease in B. garinii prevalence at one site.

Abundance of acorns: mice and ticks to follow November 16, 2016 Maine, Courier-Gazette & Camden Herald

... Dr. Richard Ostfeld of the Cary Institute of Ecosystem Studies in Millbrook, N.Y. spent several years researching the correlation between acorns, mice and ticks, and conducted experiments to predict Lyme disease risks... "In no case did inclusion of deer or climate variables improve the predictive power of models based on rodents, acorns, or both. We conclude that interannual variation in entomological risk of exposure to Lyme disease is correlated positively with prior abundance of key hosts for the immature stages of the tick vector and with critical food resources for those hosts," Otsfeld noted in the study...

Battle over tick ad by Shelter Island Association August 9, 2017 New York, Shelter Island Reporter

... “You don’t need deer to have a tick problem,” Mr. Amann said, pointing out there are problems with ticks in New York’s Central Park where there are no deer and places in Nassau County with ticks but no deer. “The idea of running around, shooting deer and there will be less ticks, is nonsense.” ...

Redding site for tick study July 11, 2017 Connecticut, The Redding Pilot

... “Where we used the combination of rodent bait boxes and fungal spray only is where we had the most success in reducing encounters with blacklegged (“deer”) ticks in people’s backyards,” ... deer reductions caused ticks to feed on alternative other available hosts, such as small- and medium-sized mammals... not able to remove enough deer to reach targeted goals [controversy regarding the deer count]

Discussion about the relationship between deer and Lyme disease January, 2016

  Use the link above to follow a discussion between local hunters and Dr. Scott Williams of the Connecticut Agricultural Experiment Station related to the effectiveness of conducting community deer culls to reduce the risk of contracting Lyme disease.  [Information provided by participants in the discussion]:  Westport, CT has seen a dramatic decline with their Lyme cases from 2005 (57) to 2012 (6) cases.  Westport has a stable deer population of approximately 600 deer per a recent FLIR survey conducted in 2012 and does not allow hunting in their town.  Redding, CT, on the other hand has used a "destroy all deer" mentality to try and eradicate Lyme with little success.  Redding's Lyme cases in 2005 were (18) cases and in 2012 (10) cases.  More information in PDF

Dr. Williams comments that as the information in the graph below shows, Lyme disease cases have "dropped precipitously in the last 15 years" when there was no hunting in the town of Westpoint based on "credible" data from the department of health:  [Below the long term graph, 2000 to 2014, of the number of reported cases of Lyme disease in Westport, CT, where the deer population has been relatively stable because the community decided not to cull their deer]

The CT DEEP is charged with the management of wildlife, [deer density not correlated to Lyme disease] January 18, 2016 Conneticut, ReddingNews.Info

... The town of Westport, CT does not allow hunting and surveys, one as recent as 2012, have shown that Westport has a stable population of approximately 600 deer, or a density of 26.8 deer per square mile. Interestingly enough, the city has seen a steady decline in the number of lyme disease cases, going from 57 cases in 2005 to just 1 confirmed case in 2014... Redding has seen an all-out siege on its deer herd the past four years resulting in a decrease of 80% in the deer herd, yet Redding has seen an increase in the number of reported cases of lyme disease...

Deer & Tick Committee on the hunt for reliable trends March 7, 2017 New York, Shelter Island Reporter

... There may be fewer deer on the Island, but no one here or in other communities seeking a way to count deer has come up with a reliable method... the committee opted to delay further investigation of an MIT study dealing with changing the DNA of white-footed mice that would then not be able to serve as conduits for ticks that spread Lyme disease...

Borrelia miyamotoi in vectors and hosts in The Netherlands 2016, Ticks and Tick-borne Diseases ... A Wagemakers, S Jahfari, B de Wever, L Spanjaard…

... Ixodes ticks transmit Borrelia burgdorferi sensulato (s.l.),the causative agent of Lyme borreliosis (LB). These tick species also transmit Borrelia miyamotoi, which was recently found to cause infections in humans... Both rodents (9%) and birds (8%) were found positive for B. miyamotoi by PCR, whereas the roe deer samples were negative...

Ireland's deer are not to blame for humans contracting Lyme disease May 9, 2016 Irish Examiner

... ‘Deer ticks’ of the species Ixodes scapularis do not draw their crucial sustenance from deer...  in one small island off Cape Cod, of state wildlife biologists going out with guns and destroying 70% of the deer...outdoorsy types on the island were just as likely to acquire a Lyme-disease infected tick in the now largely deer-free woods as they were before the deer were killed. All of the other animals carried just as many of the bugs as ever they did.  However, the notion that white deer effectively caused the disease had taken hold in rural America ...

Lyme disease: You can't blame the deer July 21, 2016 Norway, Science Daily

... the percentage of ticks with Borrelia is decreasing in areas with a high deer population (deer, red deer and moose). However, the total number of ticks is higher... "We see that the incidence of borreliosis has increased in the southern part of Norway in a period of time where both the deer population and the moose population have decreased. This is why we cannot only blame the deer for getting more of these blood-sucking parasites," says professor Atle Mysterud... TickDeer-project, which represent a cooperation between the Department of Biosciences (University of Oslo), Norwegian Veterinary Institute, and NIBIO ...

Speaker Combats Lyme Disease Spread November 4, 2015 Vermont, Middlebury Campus

... in Cranes Beach, Massachusetts. In this scenario, when the deer population was driven to zero, the nymphal tick population also decreased – but after a certain point, it began to increase again, almost reaching its initial size ... This has led Dr. Ostfeld to conclude that species other than the white tail deer influence the size of the tick population...

Many upstate communities are taking action against rising deer populations September 4, 2015 New York, WRVO Public Media

... the village of Trumansburg in the Finger Lakes started a deer management program which baits deer with corn so archers can shoot and kill ...  fewer deer sightings were reported. But residents have continued to contract Lyme disease, including one of the village board members...

The growing global battle against blood-sucking ticks August 25, 2015 Nature 

...  most Lyme-control measures focus on white-tailed deer (Odocoileus virginianus) ... When Sam Telford, an epidemiologist at Tufts University in North Grafton, Massachusetts, and his colleagues cut the deer population on Great Island in Cape Cod by 50% in the early 1980s, they saw no drop in tick numbers — the number of tick larvae on the island actually increased ...  Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies ... Ostfeld and others contend that mice are a major driver for both the tick problem and the disease problem ...

Don’t feed the ticks ...  April 24, 2015 WTOP

... New York entomologist Rick Ostfeld, who stressed that so-called deer ticks actually pick up Lyme disease when they feed on field mice, not deer. As we have stressed for many years, deer ticks may never even see a deer — but they all have to feed on mice as part of their life cycle. That’s why I just spread my annual batch of Tick Tubes around the outskirts of my property... 

Redding, Deer Reduction = Increased Lyme January 2, 2014 Connecticut,

...  From 2009-2014 the deer harvest rates in Redding; town owned open spaces plummeted by 95% ( 141 to 7 ) and town wide by 78% ( 321 to 70 ). In sharp contrast reported cases of Lyme increased by 62% + over the last 4 years despite this drop in deer harvest numbers. In comparison, Greenwich and Westport have stable populations of 25+ deer per square mile and Lyme disease rates remains low, even with deer populations nearly three times that of Redding.

Redding Deer Population and Harvest Down 80% December 18, 2014 Connecticut,

... 2009 to 2014 we see the Redding deer population and harvest rate go down by approximately 80%. [321 to 63] ...They are no longer taking about ticks as reported cases of Lyme increased by 62.5% + over the last 4 years in Redding despite the significantly decreasing deer population... When will the CT DEEP step in and put a stop to the over kill of deer...

An Increase in Ticks Carrying Lyme Disease in Connecticut June 23, 2015 Connectcut, WNPR News

... On average, scientists found about 27 percent of ticks tested positive for the Lyme-disease bacterium. "However, this year, we are early in the season, and we have found that nearly 34 percent of these ticks are infected with Lyme disease [the deer population is trending down while the percent of infected ticks increase] ...

Jamestown, Deer cull won’t work October 16, 2014 Rhode Island, The Jamestown Press, Myrna Lee, Member, board of directors Canadian Lyme Disease Foundation

...  your Town Council is terribly misled in culling deer as a solution to your tick problem ... Deer are not the only carriers of Lyme-bearing ticks. Ticks attach to anything that brushes against the vegetation where they wait for a host. So you would have to cull all creatures living in your area, including birds...

Many California bird species host Lyme disease bacteria, study finds February 26, 2015 Los Angeles Times

... Although Lyme disease cases are relatively rare in California, DNA sequencing showed B. burgdorferi’s presence in 23 of 53 species of birds tested in Mendocino County... “Our findings underscore the importance of bird behavior to explain local tick infestation and Borrelia infection in these animals,” ...

Shifting the conversation about deer control September 4, 2014 Connecticut, Stamford Advocate, Laura Simon is a wildlife biologist for The Humane Society of the United States.

.. There's a good reason that national health authorities such as the Centers for Disease Control and our own Connecticut State Health Department are not calling for increased killing to control Lyme disease -- because it won't work... In studies where as many as 83 percent of the deer were removed, tick numbers weren't impacted. They merely switched to alternate hosts...

Lyme Disease - Will Shelton go the Wrong Way? June 29, 2014 Connecticut, Shelton Patch 

...  After reviewing the numbers from the last four years,  provided by both the Connecticut Health Department and the CT DEEP we see that the deer population is now down 60% + and that Lyme disease, reported cases in Redding are up  62.5%.  In 2010 the Redding, CT reported Lyme cases were  8  and in 2013 they are now 13.  What happened to all the " Wildlife Experts " that said, " Less Deer = Less Lyme " ?  ...

A dismissal of correlation between deer, Lyme disease September 11, 2013 Connecticut, Greenwich Time

... The public needs to be provided with facts and not fear-mongering. Required reading should be "Lyme Disease: The Ecology of a Complex System" by Dr. Richard Ostfeld published last year, which synthesized just about every study written on this topic. He concluded that there is little to no correlation between deer and Lyme disease and no studies that correlate a reduction in the deer population to a reduction in the incidence of the disease. There are four small mammals, including the white-footed mouse that account for 90 percent of infected ticks...

The Truth about Lyme Disease October 23, 2013 Humane Society of the United States

..Killing deer can make matters worse ... Deer are one of many vertebrate hosts that carry this tick... Killing deer will not reduce the risk of Lyme disease for people ... If one were to really try to exterminate Lyme disease by focusing on the tick's hosts, that would mean killing most mice, chipmunks, squirrels, raccoons, skunks, rabbits, popular songbirds, and even lizards ...

Culling deer won't reduce Lyme disease June 20, 2013 British Columbia, Victoria Times Colonist

... According to the B.C. Centre for Disease Control, there is no evidence to support an epidemic of Lyme disease in B.C. ,,, Culling deer does not reduce Lyme disease occurrence... unless we want to eradicate all small mammals as well as the songbird population, our dogs and horses and the deer, we will have to learn to tolerate the western black-legged tick ...

The automatic association of Lyme disease with deer may be flawed August 27, 2014 Massachusetts, Martha's Vineyard Times 

... The abundance of deer and near absence of ticks in Aquinnah’s lush wetland forest, and abundance of ticks despite a lower number of deer in Chilmark’s dry oak forest suggest that the differences go deeper than the relationship between deer and their parasites...One of the chief differences between them is that oak forests produce more starch in the form of acorns that squirrels can hoard, leaving plenty for other rodents such as white-footed mice, which serve as the hosts for immature deer ticks. The mice are a crucial carrier of the ticks, which thrive, even when there aren’t many deer ...

Strange events will lead to increase of Lyme disease this year March 22, 2012 Fox News 

... But don't blame the deer. The predicted rise in ticks that carry Lyme disease is actually the result of a cascade of ecological events that started back in 2010 and involves acorns and mice, says Richard S. Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y.... The white-footed mouse is the perfect host for ticks (low to the ground and not bothered by the parasites), said Ostfeld, who has published several studies showing the population of mice, not deer, is more directly correlated to the tick population

Duke Forest, Our illogical war on deer February 9, 2013 North Carolina, The Durham News, Karin Yates

...  I recently witnessed a buck lying down in a yard in Chapel Hill with an arrow protruding form his left hind quarter... It is important for us to understand that deer do not “carry” or “spread” Lyme disease. In fact, deer provide a buffer between the host (white-footed mouse) and humans by “collecting” the ticks on themselves.  According to John Rohm of the Virginia Department of Game and Inland Fisheries, “Reducing deer density by X will not = X percentage reduction in Lyme disease cases. ... Deer should not be blamed for the current Lyme disease situation. Integrated pest management would be more effective than focusing solely on deer.”

Tick...Tick...Tick, white-footed mouse main reservoir for Lyme disease March 16, 2011 Rhode Island Directed, produced, and narrated by Mary Healey Jamiel, "Hidden in the Leaves" is a 24-minute film about deer ticks. The DVD features the work of Thomas N. Mather, Ph.D., Director of the University of Rhode Island's Center for Vector-Borne Disease

One study often cited as an example of reducing Lyme disease by reducing the deer population, was done on an offshore island with little biodiversity so few alternate hosts for ticks. Rand, P.W., et al. 2004. Abundance of Ixodes scapularis (acari:Ixodidae) after complete removal of deer from an isolated offshore island, endemic for Lyme disease. Journal of Medical Entomology 41:779-784 

TICK CONTROL B Trapping, H Munugement - Biology of Ticks, 2013, p. 427

... some years after deer reduction tick densities were similar to those in some years before deer reduction (Deblinger, 1993).  Indeed, a meta-analysis of deer exclusion data sugged that small deer exclosures can actually increase densities of some tick species (Perkins, 2006).  These conflicting results apparently are derived from interacting factors that influence tick numbers beyond the effects of host density alone (e.g. the movement of small vertebrates hosts, physical conditions in differend habitat types, exclosure size and habitat fragmentation effects), and some of these can shift in importance from year to year.  For example... The numbers of nymphs in these exclosures declined after 3 years their levels within exclosures had increased enough to be comparable to outside control areas.

WILSON, M. L., DUCEY, A. M., LITWIN, T. S., GAVIN, T. A. and SPIELMAN, A. (1990), Microgeographic distribution of immature Ixodes dammini ticks correlated with that of deer. Medical and Veterinary Entomology, 4: 151–159. doi: 10.1111/j.1365-2915.1990.tb00273.x

ABSTRACT. In order to determine whether the small-scale distribution of immature Ixodes dammini Spielman et al. corresponds closely to the activity patterns of white-tailed deer, Odocoileus virginianus (Zimmerman), these relationships were examined in a site on Long Island, New York, U.S.A. We first determined the extent and temporal pattern of adult ticks feeding on deer by examining twenty-three resident deer tranquilized during September-December 1985.1, dammini adults infested deer throughout this fall period, most abundantly during October and November. With radio-telemetry collars attached to deer we determined the relative frequency that they occupied 0.25 ha quadrats of the study site. During the following summer, we examined white-footed mice, Peromyscus leucopus (Rafmesque), that inhabited these quadrats and removed immature ticks from each. 8975 larval and 163 nymphal /. dammini were removed from 208 mice trapped in forty-three such quadrats. The frequency of deer using these quadrats was positively correlated with both the number of larval and of nymphal ticks per mouse. These results suggest that risk of I.dammini-borne zoonotic disease may be decreased by locally reducing deer density in sites that experience intense human activity.

Localized Deer Absence Leads to Tick Amplification

Localized Deer Absence Leads to Tick Amplification

Sarah E. Perkins, Isabella M. Cattadori, Valentina Tagliapietra, Annapaola P. Rizzoli and Peter J. Hudson Ecology Vol. 87, No. 8 (Aug., 2006), pp. 1981-1986 Published by: Ecological Society of America

Deer support high tick intensities, perpetuating tick populations, but they do not support tick-borne pathogen transmission, so are dilution hosts. We test the hypothesis that absence of deer (loss of a dilution host) will result in either an increase or a reduction in tick density, and that the outcome is scale dependent. We use a complementary methodological approach starting with meta-analysis, followed up by a field experiment. Meta-analysis indicated that larger deer exclosures reduce questing (host-seeking) tick density, but as the exclosure becomes smaller (&lt2.5 ha) the questing tick density is increased (amplified). To determine the consequences for tick-borne pathogen transmission we carried out a field experiment, comparing the intensity of ticks that fed on hosts competent for tick-borne pathogen transmission (rodents) in two small (&lt1 ha) deer exclosures and their replicated controls. Intensity of larval ticks on rodents was not significantly different between treatments, but nymph intensity, the tick stage responsible for tick-borne encephalitis (TBE) transmission, was higher in deer exclosures. TBE seropositive rodents were found in a deer exclosure but not in the controls. We propose that localized absence of deer (loss of a dilution host) increases tick feeding on rodents, leading to the potential for tick-borne disease hotspots.

Deer-free areas may be haven for ticks, disease Penn State Study

Reduced abundance of immature Ixodes dammini (Acari: Ixodidae) following incremental removal of deer. J Med Entomol. 1993 Jan;30(1):144-50 Deblinger RD, Wilson ML, Rimmer DW, Spielman A. Trustees of Reservations, Beverly, MA 01915.


The abundance of immature Ixodes dammini Spielman, Clifford, Piesman & Corwin was monitored for 9 yr (1983-1991) before and during the controlled, limited hunting of white-tailed deer, Odocoileus virginianus (Zimmerman), at a coastal Massachusetts site. Deer abundance was reduced from an estimated 350 during 1985 to approximately 60 during 1991. Although annual fluctuations were large, mean larval I. dammini abundance declined from 20.8 per white-footed mouse, Peromyscus leucopus (Rafinesque), during 1983-1986 before deer reduction to 10.3 per mouse following deer reduction (1987-1991). Similarly, mean nymphal I. dammini abundance declined from 2.7 per mouse before intervention to 1.6 per mouse after intervention. Immature I. dammini population fluctuations were not associated with those of P. leucopus. The total population of larvae infesting P. leucopus declined from 3,596 ticks before intervention to 1,535 ticks after intervention. Concurrently, the total nymphal population declined from 417 ticks before intervention to 187 ticks after intervention. The number of feeding adult female I. dammini on deer increased as deer density decreased.

Freehold Township > Tick Borne Disease Ecology > Current Research Study Results. After three seasons, the estimated deer population was reduced by 46.7 %, from the 2002 post-fawning estimate of 2,899 deer (45.6 deer/km2) to a 2005 estimate of 1,540 deer (24.3 deer/km2). There was no apparent effect of the deer culling program on numbers of questing nymphal ticks in the culling areas and the overall numbers of host-seeking ticks in the culling areas appeared to increase in the second year of the program. The Lyme disease incidence rate generated by both passive and active surveillance systems showed no clear trend among years and did not appear to vary with declining deer density. Cayuga Heights, NY: Richard Ostfeld, PhD Senior Scientist, the Cary Institute of Ecosystem Studies Author of Lyme Disease: The Ecology of a Complex System(2010, Oxford Univ. Press)

• DEIS incorrectly states that linear correlations exist between deer and ticks • No scientific data support the existence of a deer density threshold below which ticks decline to low numbers • Deer actually reduce the prevalence of Lyme infection in tick populations • Adult blacklegged ticks feed on at least 27 mammal species, not just deer • It’s misleading for DEIS to use Monehgan Island study to predict what will happen in Cayuga Heights. Read Statement

Cayuga Heights, NY: Tamara Awerbuch, PhD ,Instructor, Department of Population and International Health, Harvard School of Public Health

• Incorrect assumptions are made in DEIS about the relationship between deer and “deer ticks”, which have no basis in science • There is no linear correlation between killing deer and the tick population • White-footed mice, and not deer, are the carriers of the agent of Lyme disease • In Ipswich, MA, Lyme disease kept growing following deer-killing program • “there is NO scientific justification for a deer killing program in your community”. Read Statement