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Ticked off
High deer population contributes to Lyme disease
Jun 5, 2008
As the weather warms and people head outdoors, an enemy lies wait in the high grasses: the deer tick. The Post
begins a four-part series this week, taking a look at Lyme disease. This week, we examine the connection between the spread of Lyme and the prevalence of deer. Next week, the Post
delves into the difficulties of diagnosing this confusing disease. The third week we will look at prevention, and finally we will look at how the Infectious Diseases Society of America and the government are working together to come up with research standards to find out more about Lyme disease.
Many people look at deer as harmless, bushy-tailed, vegetarians that quietly meander through the woods just looking for something good to munch on. While all that may be true, the overpopulation of these quiet forest dwellers is becoming a problem throughout Fairfield County.
A recent deer count done by the Connecticut Department of Environmental Protection found about 29 deer per square mile throughout the county. The department assumes that it misses about 50% of the deer as it looks at an area from a helicopter, which would make the actual population about 58 per square mile — a higher population than other counties in the state.
Greenwich resident Kristen Manolis was involved in a car accident when a deer jumped in front of her car in January. She suffered a concussion that caused headaches and nausea for months after the accident.
Ms. Manolis said she’s an animal lover, but is concerned about the overpopulation of deer, as she often sees about 30 deer in her or her neighbors’ yards at a time.
She said it’s a problem when it comes to Lyme disease and a serious problem for motorists.
More deer, more Lyme
A higher population of deer means a higher prevalence of Lyme disease.
Dr. Gloria Scholl, chairwoman of the Fairfield County Municipal Deer Management Alliance, said there is a direct correlation between deer populations and the prevalence of Lyme disease in communities throughout the county.
Preliminary study results showed that 60% of the adult ticks collected in Greenwich, Bethel, Easton, Newtown and Redding were infected with Lyme disease. The results are part of a 14-town study conducted by the alliance in efforts to find the prevalence of Lyme disease in trafficked areas like playgrounds and parks.
The science that connects deer to Lyme disease involves the deer tick’s need for adult deer to reproduce. While smaller animals like rabbits, chipmunks and mice carry the spirochete bacteria that causes Lyme disease, the adult deer tick can’t reproduce without feeding off deer. Deer can carry about 100 ticks at a time on their ears.
Dr. Scholl said throughout the different phases of a deer tick’s life, it will feed on different animals. Tick larvae are small and mostly feed off mice and chipmunks where they pick up Lyme disease. While larger ticks will still feed on the smaller animals, research is still being conducted on what part of deer blood allows the tick to reproduce.
According to the Department of Environmental Protection, about 29,000 human cases of Lyme disease were reported in Connecticut from 1996 through 2007.
Dr. Daniel Cameron, president of the International Lyme and Associated Diseases Society, said he continues to see more new and chronic cases.
“It continues to be a constant problem for towns in Fairfield and Westchester counties,” said Dr. Cameron who has a private practice in Mount Kisco, N.Y., and sees many patients from the area.
The right environment
Where are all the deer coming from?
Unlike other wildlife populations that are adversely affected by human encroachment into their habitats, deer thrive on the continuous development throughout the county.
Dr. Scholl said the deeper you go into mature woodlands there are dark areas with less vegetation for the deer to feed. Increasing development has created more edges to forests where deer can thrive on natural vegetation as well as plants from landscaped lawns.
Development has also limited the space where people may hunt. Fewer hunters and better areas for deer to find food is a combination that leads to deer populations growing very quickly, Dr. Scholl said.
Aside from development, warmer winters have allowed a larger population of deer to thrive because more food is available to them and allow the deer tick to live throughout the winter.
Solving the problem
The unbalance in deer population isn’t good for humans or deer, say experts. However, Dr. Scholl said deer population control is a political issue and should be handled statewide before towns can adopt plans.
She added that three communities in the Northeast serve as examples of how decreasing the deer population can lessen Lyme disease outbreaks. One example is Mumford Cove in Groton where 30 cases of Lyme disease were reported per year when the deer population was about 110 deer per square mile.
By using a program organized by the Connecticut Department of Environmental Protection, the community now reports about two cases of the disease per year and has controlled the deer population to about 11 deer per square mile.
The program uses volunteer “hunters.” They’re not really hunters because they aren’t looking for deer in the traditional sense, Dr. Scholl said. To make the hunting safe in residential areas, the hunters sit in tree stands at designated locations and wait for deer to come directly underneath the tree baited with corn bait.
Two volunteers are used a year to keep deer levels the same.
Ms. Manolis said towns need to take action in controlling deer populations and suggested that a day and time be set aside for hunters to be able to hunt deer throughout town. Setting a day and time would keep non-hunters away, she said.
Ms. Manolis added that the venison from the hunting days could be donated to food pantries or shelters for people who need food creating a full circle service that many people can benefit from.
While some experts feel that hunting is the best option for deer population control, other control methods exist and are being used. Fire Island, N.Y., has a birth control program in place to reduce the number of deer at Robert Moses Beach.
Many people use fences around the perimeter of their homes to keep deer off their lawns to prevent damage to their landscaping and the spread of ticks in their yards. Others use tick sprays on their lawns specifically for deer ticks or ultrasound hardly audible by humans but very uncomfortable for deer.
Pleasantville, N.Y.-based DeerTech offers a system that encompasses all three alternative solutions to protect lawns and landscaping from damage caused by deer.
Greenwich resident Greg Lake, president of DeerTech, said the system attacks deer on multiple senses.
He added most people install the system as an insurance policy to protect their landscaping and not as much to protect them from ticks and Lyme disease.
“There is no sure-fire or single bullet,” said Mr. Lake about the various methods to deter deer, adding that the DeerTech system works best because it’s multi-faceted.
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