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Monday
May192014

lyme disease: what is it and how to prevent it

Lyme disease has been increasing in Vermont. In 2012, the Vermont Department of Health received over 500 case reports. Everyone, who spends time outdoors, in their yard or further afield, needs to be informed about the basics of the disease because it can have serious health consequences. However, it is preventable using precautionary measures.

Lyme disease is caused by a spirochete (bacteria with a spiral shape) called Borrelia burgdorferi, which is carried and transmitted by black-legged ticks (Ixodes scapularis), also known as deer ticks. After hatching from its egg in early spring, the tick matures through three life cycle states – larva, nymph and adult. The larvae can be as small as .5mm., but are not capable of transmitting Lyme disease. The nymphs, which are about 1.5 mm., appear in spring when the temperature exceeds 40 degrees F. Nymphs molt into adults (as small as 2.5 mm. – the side of a sesame seed). Ultimately, a male and female adult mate and reproduce, and the female lays her eggs on the ground.

The tick requires blood from a host in order to live. Many hosts can serve as a source: mice, chipmunks, deer, birds, dogs, humans and others. White-footed Mice are the most abundant host. They are carriers, but don’t become sick. Birds can eliminate a portion of their ticks with preening. There are some reports that deer, although hosts, appear to clear the organism with an efficient immune system.

Once a tick ingests a blood meal from its host, it drops off into the underbrush and simply waits until it can attach to the next victim/host passing by. Deciduous woods with leaf litter and an understory are prime tick territory, but grasslands are also rich tick habitat.

Once a tick bites a human, it remains attached for several days as it feeds and obtains a blood meal. A tick must bite and stay attached for 24-36 hours before it can transmit Lyme disease. The ingested blood signals the spirochete, residing in the tick gut, to undergo changes that allow it to move into the circulation and eventually into the tick’s saliva. It is the saliva that transmits the organism to you.

If you find a tick on your skin, remove it, because prompt removal can prevent Lyme disease. Use a fine tipped tweezers and grasp the tick close to your skin; with a steady motion, pull straight upward. After removal of the tick, wash your hands with soap and water or use an alcohol-based tissue wipe you have brought with you.

If the tick is attached to you for less than 36 hours, your chance of getting Lyme disease is small. Nonetheless, it is wise to be on the alert for symptoms (see below) of Lyme disease. Symptoms can begin three days after a tick bite, or as late as 30 days, but usually appear within one to two weeks. If you develop symptoms, contact your doctor. Opinions vary as to the urgency of initiating oral antibiotics. Some advocate contacting your doctor as soon as possible after tick removal, since doxycycline, given within 72 hours of a tick bite, is often effective in preventing Lyme disease. Others say you should be okay if you get the tick off early: just watch for symptoms and then contact your health care provider.

Symptoms occur 3 to30 days after an infected tick bite. A characteristic erythema migrans (EM) skin rash appears in up to 80% : an expanding reddish rash arises at the bite site. The center may clear as it spreads (bull’s eye). It may be warm, but is usually not painful or itchy.

An EM rash must be distinguished from a rash caused by an allergic reaction to a tick or other insect bite. A skin rash due to an allergic reaction usually occurs within a day after the bite, does not grow in size, and disappears within a day or two.

Other early symptoms include: fatigue, chills, fever, muscle and joint pain, headache and swollen lymph nodes. Late symptoms, indicative of disseminated disease, include: numbness and pain in arms or legs, paralysis of facial muscles (usually on one side of the face, i.e. Bell’s palsy), fever, stiff neck and headaches (possible meningitis), abnormal heartbeat, joint pain and swelling and chronic nervous system problems. While early treatment is best, most people diagnosed later in the course of illness can also be successfully treated.

To prevent Lyme disease, avoid walking through high grass and brushy areas. Stick to the middle of the trail. Wear long pants and long-sleeved shirts to minimize skin exposure. Tuck your pants into your socks to keep ticks out. Wear light colored clothing so you can see the ticks on your cloths. After being outdoors, check your skin thoroughly, searching for what may look like nothing more than a freckle or speck of dirt. Remove any tick promptly. Shower within a few hours of returning home to wash off unattached ticks that you may have missed. Throw your clothes in the dryer on high heat for one hour (heat kills ticks). Permethrin (available at sporting goods stores), is an insecticide and repellant that can be sprayed on your clothing, shoes and gear, but not on your skin.

For more information, contact the Vermont Department of Health at 800-640-4374 or 802-863-7240 or click here to visit their website. Click here to order the booklet pictured here from the Vermont Department of Health.

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