Ticks and Your Health
Despite the Foundation's constant efforts to preserve the island's character and keep its properties safe, the deer tick is found island-wide. The best defense against these tiny but potentially harmful creatures is to thoroughly understand the potential problems that they can cause and how to deal with them. We hope that this information about ticks and tick-borne diseases will help you to more safely enjoy the Foundation's properties.
Lyme Disease is a bacterial infection resulting from the bite of a deer tick. The disease affects both sexes, all age groups, and can be transmitted year-round. Often it starts as an expanding ring-like rash and can, if untreated, develop into a chronic disease that includes arthritis and damage to various nerves. When diagnosed early, the disease can be effectively treated with antibiotics. You can protect yourself from becoming infected.
Efforts to Identify Lyme Disease
An intensive effort to study the increasing frequency of tick-transmitted diseases in humans began in 1973 with investigations by the U.S. Center for Disease Control and the Harvard School of Public Health. Research done on Nantucket and elsewhere lead Harvard scientist Dr. Andrew Spielman to identify a new species of tick–the deer tick. Other work by Dr. Spielman and his colleagues produced a description of the tick's complex life cycle and the crucial relationship the tick has with its natural hosts.
As a result of these and other scientific inquiries, we now know a great deal about Lyme Disease, including that it is caused by a corkscrew-shaped bacterium (a spirochete) called Borrelia burgdorferi. The spirochete is named for Dr. Willy Burgdorfer, who, in 1982, first identified it in the deer tick. It is found in warm-blooded animals in the wild, including the white-footed mouse (Peromyscus leucopus). Dr. Allen Steere, working at Yale University, headed a team which first described the epidemic form of this disease. The illness was named in 1976 after the town of Lyme, Connecticut, where it was originally reported.
Transmitting the Infection
The deer tick (Ixodes dammini) is responsible for transmitting the spirochete to mice and humans. It is not an insect, but a crawling, wingless, arachnid, closely related to spiders. At all stages of its life, it is considerably smaller than the more conspicuous American dog tick. Deer ticks are most abundant along the edges of wooded areas and feed on various animals, or hosts, including mice, birds, deer, dogs, cats, and occasionally humans.
Deer ticks have a two-year life cycle. In the fall, most adult ticks will mate while attached to the white-tailed deer (Odocoileus virginianus). Weighted down by her blood meal, the female falls to the ground while the male continues to wander on the deer throughout the winter, looking for other female ticks to mate with. In the spring the female deposits eggs, which hatch into six-legged larvae in early-summer, and then dies.
During the first summer, the dark brown, oval-shaped larvae--usually no bigger than a period on this page--feed once (for about two or three days) on the blood of a host and then enter a lengthy period of dormancy. Because they are hatched at ground level, larvae usually feed on the blood of a white-footed mouse. If infected with the Lyme Disease bacterium, the white-footed mouse serves as the reservoir, transmitting the spirochete to the uninfected feeding tick. The following spring the larvae molt, entering a second immature stage called the nymphal stage. The growing (though still speck-sized) nymphs seek out and attach themselves to a host, this time to feed for three or four days. Ticks are most likely to attach themselves to humans during the larval or nymphal phases of their life cycle. At the end of October, nymphs molt into the adult stage.
Like larvae and nymphs, the larger adults (about the size of a small pinhead) are capable of feeding on a variety of hosts, including man, but are most commonly found on the white-tailed deer. It is here that the entire cycle begins anew.
A significant number of the deer ticks–from 15 to 40 percent of nymphs and 30 to 60 percent of adults, depending on geographic area–are infected with the Lyme disease spirochete. When these ticks bite and remain attached for two days, the spirochete can pass into the host's bloodstream where it multiplies and from where it can then be taken up by other deer ticks.
Habitats and Distribution
Although deer tick infestations are most frequent in coastal areas from Virginia through Massachusetts, dense populations have become established inland in New York and Pennsylvania. The tick's increasing geographical distribution is a result of its being carried by birds. Its preferred habitats are the edges of shrubby woodlands where deer are abundant, whether near marshes, on sand dunes, or in upland fields.
Tracking Ticks Down
When you are outside–especially in woodland edges where deer are known to be present–be on the lookout for the tiny deer ticks on your body or clothes. You should also check yourself thoroughly when you get home. It takes time for a tick to attach itself to your skin. Ticks roam, generally migrating upward. Larvae and nymphs live near the ground so check your ankles and legs. Adults are commonly found clinging to plants at about waist height, so carefully examine your waistline, groin area, arms, back, neck, and scalp.
When first bitten by a deer tick, there is usually no pain or reaction. Because of its small size, the deer tick's presence generally goes undetected. In most cases it bites, draws blood, and drops off. With vigilance and because an infected tick must be attached for 24 to 48 hours to transmit the spirochete, only a small percentage of tick bites result in Lyme Disease.
Removing Attached Ticks
The recommended way to remove attached ticks is to use small, pointed tweezers. Grasp, but do not squeeze, the tick where its mouth parts enter the skin and tug gently, but firmly. Sometimes, the barbed mouth parts of the tick will not let go, but be persistent and remove as much of the tick as you can. Place the tick in a container that is marked with the date, the body location of the bite, and where you think you were when the tick climbed onto you. Your doctor may find this information extremely helpful for an accurate diagnosis if symptoms of Lyme Disease appear. After the tick has been removed, disinfect the site of the bite by wiping it thoroughly with rubbing alcohol.
Indications of Early Lyme Disease
The most common early symptom of the disease is a red rash, appearing at the bite location or as a secondary rash appearing elsewhere. This generally happens about two weeks after the tick has finished feeding and has detached itself. (Surprisingly, only about half of infected individuals ever remember seeing a rash.) As the spirochetes multiply, the rash may develop into a reddish ring about the size of a silver dollar, sometimes expanding to cover an area as wide as the patient's body with a bull's-eye-like configuration (known medically as erythema migrans). It is painless, can feel warm to the touch, and blanches when pressure is applied. If left untreated, the rash may expand for several weeks, and then fade away.
Typically, within a week or two of being bitten by an infected deer tick, Lyme Disease causes mild flu-like symptoms (fatigue, fever, chills, stiff neck, aches and pains, sore throat, or headaches). Individuals who have had a deer tick bite accompanied by a rash or flu symptoms should promptly consult a physician since medical attention during its primary stages can put a quick end to Lyme Disease.
Symptoms of the Advanced Disease
After the illness has become chronic–weeks to several months following the bite–signs of the untreated disease can include problems involving the heart, joints, or nervous system. Also, such symptoms may include dizziness, weakness, and an irregular heartbeat. Nervous system problems are characterized by intermittent headaches, difficulty in concentrating and sleeping, irritability, and poor coordination. Some people develop weakness of facial and other muscles.
If left untreated, symptoms may also include joint pain and swelling. The pain may occur in a single joint (most commonly in the knees), go away after a few days to a few weeks, and reappear elsewhere. During this stage, the disease can be easily misdiagnosed as arthritis. Though movement can be extremely painful, usually any damage done to cartilage or bone is reversible. The disease can be readily treated, even at this stage.
After many years--a decade or more following infection--Lyme Disease can severely damage the brain and other nervous tissues, sometimes mimicking Alzheimer's disease or Multiple Sclerosis. Recurring episodes of arthritis may result in erosion of the cartilage of the joints of the long bones. Medical treatment this late in the disease is difficult and may not be successful.
Diagnosis and Treatment
Lyme Disease is frequently difficult for physicians to diagnose because its symptoms can occur in such varied combinations. In some people, the tell-tale rash never appears. Other people who do not experience a rash or neurological problems may have joint swelling and pain as their first symptoms. However, with medical research has come the development of a special blood test that identifies antibodies produced by the body's immune system as it defends against the multiplying spirochetes. A test is also available to confirm whether or not a tick is carrying the Lyme Disease spirochetes. So if you have the tick that bit you, tell your doctor. Knowing that a person has been bitten by a deer tick, doctors (in areas where Lyme Disease is well-established) may elect to initiate treatment without waiting for laboratory confirmation. In such situations, a doctor's decision to initiate treatment depends on an examination of the physical evidence, symptoms, and the patient's recollections.