Most cases of Lyme disease are transmitted by nymphal ticks, which feed in the late spring and early summer. ("Nymphal" refers to one of the early stages in the life cycle of ticks.) As a result, this is the time when Lyme disease is generally acquired. Nymphal deer ticks are small -- about the size of a poppy seed -- and so their presence is often missed. Adult ticks, which feed in the fall, can also transmit Lyme disease to humans, but because of their larger size they are usually seen and removed. In addition, humans tend to be more fully clothed in the fall, so ticks find it harder to find a place for attachment.
The first approach to avoiding Lyme disease is avoiding tick bites.
Clearing leaves and wood piles from around houses and yards can make the area less hospitable to ticks, as well as their deer and mouse hosts. When planning to spend time in a tick infested area, wear clothing to cover exposed skin such as long-sleeved shirts, and long pants, which can be tucked into socks. Wear light colors to make it easier to see ticks that have climbed onto clothing. DEET-containing insect repellents can be applied to clothing and exposed skin, and permethrin can be applied to clothes. Note that DEET can cause skin and eye irritation, and should be applied carefully to a child's skin by a parent. Permethrin, which kills ticks directly upon contact, should be applied only to clothing, not to skin.
Borrelia burgdorferi resides in the gut of its host tick. In order for it to be transmitted to humans, it must first travel to the feeding tick's salivary gland. This process takes about 15 hours. Lyme disease cannot, therefore, be transmitted during the first 15 hours of tick attachment. Transmission of Lyme disease is, in fact, rare before 36 hours of attachment, and generally occurs only when ticks have been feeding for two to three days. By this time the tick is engorged (filled full with blood from its host), and easily visible. Ticks that are removed before they are engorged virtually never transmit Lyme disease.
The second approach to avoiding Lyme disease is to do a "tick check" at the end of each day spent in an endemic area.
Ticks can be anywhere on the body, but they especially like warm, hidden areas, like the underarm, groin, and the back of the knee. They can be removed with a tweezers placed as close to the skin as possible. The tick mouth parts may remain in the skin but will not transmit Lyme disease.
A deer tick from a Lyme-endemic area that is engorged will transmit Lyme disease about 10% of the time. There are two approaches to dealing with this situation. One is to observe the site of the bite for the development of the Lyme rash (erythema migrans), and monitor for "flu-like" symptoms for the next two to three weeks. Antibiotics can then be started if symptoms develop. An alternative is to take one double dose of doxycycline (200mg), which will reduce the risk of Lyme disease's developing to about 1.3%. Because the risk is not completely eliminated, however, you will still need to monitor for symptoms of Lyme disease.
A bite from an unengorged deer tick carries an extremely low risk of infection, and so does not justify the use of preventive antibiotics.
Thus, the third approach to Lyme disease prevention might include a single 200mg doxycycline dose after removal of an engorged deer tick, if you are in a region where there is known to be Lyme disease.
Symptoms of early Lyme disease can include a "bull's eye" rash (erythema migrans), fevers, headache, muscle and joint pains. Later manifestations of Lyme disease can include arthritis, heart block, Bell's palsy, radiculopathy (that is, pain and other symptoms like numbness, tingling, or weakness in your arms or legs that is caused by a problem with your nerve roots), meningitis, central nervous system disease, and chronic neuropathy (nerve damage that can cause symptoms such as weakness, numbness, abnormal sensations such as burning, tickling, pricking or tingling, and pain in the arms, hands, legs and/or feet.)
Treatment of Lyme disease depends on the stage and form of the disease. The symptoms of Lyme disease can, at times, take weeks to months to completely resolve. Symptoms are often not completely gone by the end of antibiotic treatment.
Early Lyme disease: No blood testing necessary.
Patients are treated with 10-21 days of one of the following oral antibiotics:
Meningitis or radiculopathy:
Patients are treated with intravenous ceftriaxone 2 grams daily for 2-4 weeks.
Patients have lumbar puncture so that physicians can determine appropriate treatment:
Sometimes the signal from the heart's upper to lower chambers is impaired or doesn't transmit properly. This is "heart block" or "AV block." This does not mean that the blood flow or blood vessels are blocked. Patients are treated with oral antibiotics for 2-4 weeks for "first or second degree" heart block. Intravenous ceftriaxone is given for 2-4 weeks for "third degree" heart block.
Central Nervous System Disease or Chronic Neuropathy:
Patients are treated with intravenous ceftriaxone for 2-4 weeks.
Remember, Lyme disease is a preventable, and treatable disease. Be cautious, but enjoy your spring and summer!
Reviewed: 11/27/2009 Published: 6/14/2004