ASK THE DOCTOR: Incidence of Lyme disease is low, despite anxiety
By DR. JIM MITTERANDO
The Patriot Ledger

Q. My friend recently had Lyme disease. Can I catch it from him? What are the symptoms of Lyme disease? What do I do if I have a tick bite? Is the Lyme disease vaccine worthwhile?

A. Lyme disease is caused by bacteria transmitted to animals and humans by bites from hard-to-detect deer ticks.

These ticks, about the size of a poppy seed when young, grow only to the size of a sesame seed and are much smaller than common dog ticks, which do not cause Lyme disease.

Finding deer ticks is doubly difficult, because they usually crawl into and attach themselves to more hidden and hairy areas, such as the groin, back of the knees, armpits and scalp.

Remember, though: Every deer tick does not carry Lyme disease and only 1 percent to 5 percent of those people bitten will develop the disease. Detection and removal of the tick within 24 hours will greatly reduce the odds of contracting the disease, because research indicates that infected ticks don't begin transmitting Lyme disease for at least 36 to 48 hours after attachment.

Watch for rash

Deer ticks, which neither jump nor fly, cling to low plants in brushy, wooded or grassy places and attach themselves to animals or people that brush against the plants. They may live in grassy dune areas, but not on open beaches. The earliest sign of Lyme disease is a rash, which may appear 3 to 30 days after a tick bite. This rash, called erythema migrans, usually starts at the site of the tick bite and expands to several inches in diameter. The center of the rash may become clear as it enlarges, creating a "bull's eye" appearance. Some people with Lyme disease have several red spots. The rash may be warm, but usually is not painful. Often, people with the rash do not even notice they have been bitten.

Not all rashes that appear at the site of a tick bite are the result of Lyme disease. Any insect bite may trigger an allergic, itchy reaction that may improve with antihistamines, such as Benadryl or Claritin.

Allergic reactions usually occur within hours to days after the tick bite. If the rash becomes painful, it may be infected and require antibiotics.

After noticing the rash, some people who have Lyme disease may start to feel feverish, chilly, lethargic and experience headaches, stiff neck, muscle aches and joint pain. About 20 percent of infected people do not develop a rash and only have the flu-like symptoms.
If untreated, the rash will disappear in about a month. Weeks to months later, though, those with untreated Lyme disease often will develop arthritis, including intermittent episodes of joint swelling and pain.

Lyme disease can spread to the nervous system causing Bell's palsy (a condition that causes the face to droop) or, less commonly, meningitis.

In rare instances, Lyme disease can spread to the heart, causing an irregular or slow heartbeat. Very few, if any, people die of Lyme disease; nor is it contagious.

These days Lyme disease is easily treatable with antibiotics such as Amoxicillin, Doxycycline and occasionally Ceftin, usually taken for three weeks. Rarely, IV antibiotics need to be used to treat Lyme meningitis. Most symptoms resolve after treatment, though 10 percent of people have persistent arthritis.

Fortunately, relatively few people contract Lyme disease. In most of Massachusetts, Lyme disease occurs in about 1 in every 10,000 people. The incidence rises to about 4 cases in every 10,000 people in Cape Cod and to 120 people per 10,000 on Nantucket. In Connecticut, where the disease was first described in the town of Old Lyme in 1975, about 10 cases occur in every 10,000 people, double the incidence of Rhode Island.

Remain calm

If a deer tick bites you, do not panic.

To remove the tick, use a pair of fine-tip tweezers. Grasp the tick firmly by the barbed mouth parts of the head. Be careful not to squeeze or twist the tick body. Pull firmly and steadily until the tick comes out. If any tick mouth parts remain in the skin, you can leave them alone or carefully remove them the same way you would a splinter or consult your physician. The bacteria that cause Lyme disease are in the tick's abdomen, which is removed even if the mouth parts remain.

Don't try to kill the tick or get it to loosen its grip by covering it with petroleum jelly, burning it with a hot match or rubbing it with alcohol or nail polish remover. Those methods don't work.

After the tick is removed, monitor the bite area and the rest of your skin over the next month for a rash. If a rash appears, see your doctor and be sure to tell him or her that you were bitten by a tick, what size and when. Only people who get sick and/or get a rash after being bitten by a tick need antibiotics.

If the tick was present for less than 72 hours, there is a 1 percent chance of infection and antibiotics are not recommended for prevention.

The risk of contracting Lyme disease rises when a deer tick is present for more than 72 hours, or if it was engorged with blood, according to a recent study in the New England Journal of Medicine. In that case, taking two Doxycycline pills one time may prevent infection.

Blood tests for Lyme disease are only useful weeks after a deer tick bite in people with a rash or flu-like symptoms. The blood test is not necessary and certainly is not perfect; such tests miss 40 percent of people with early Lyme disease and produce false positive readings in 10 percent of uninfected people.

The anxiety about Lyme disease is out of proportion to the incidence of the illness. Controversy abounds as to whether chronic Lyme disease or post-Lyme disease syndrome exists.

Precautions

1. The best way to prevent Lyme disease is to prevent tick bites. During peak deer tick season (May to August), consider wearing long-sleeved shirts and long pants.

2. For added protection, tuck your pant legs into your socks or boots. Remember that ticks usually live close to the ground, especially in the moist, shaded center of paths and trails.

Apply an insect repellent containing DEET to clothes or exposed skin, or one containing Permethrin to your clothes only. On children, use products that contain no more than 10 percent to 15 percent DEET. On adults, limit the DEET to 30 percent to 35 percent.

Do not use insect repellent on infants. Don't apply it to the face and hands of children, either.

After you return indoors, carefully check your skin and each child's skin, body and scalp for ticks and rashes. Check your pets for ticks, too.

A vaccine, LYMErix, is available, but it's only 75 percent effective and not for everyone. Ask your doctor about the vaccine if you live in an area where Lyme disease is common and you spend prolonged periods of time outdoors.

People who have been vaccinated still need to take preventive measures to protect against deer tick bites.

Becoming "immune" requires three injections in 12 months, the second vaccination 1 month after the first and the third 11 months later. Because immunity may wane rather quickly, the person may need booster injections every few years.

Recently, the Food and Drug Administration began to investigate concerns that the vaccine may cause arthritis in some people. Another drawback: People who have been vaccinated require a special blood test to detect Lyme disease. The vaccine has not yet been approved for use in children younger than 15, though preliminary tests show it to be effective in children.

Dr. Jim Mitterando is a family doctor at Health Care South/Cohasset Family Practice and a staff member at South Shore Hospital in Weymouth.

Readers should send questions to: Ask the Doctor, The Patriot Ledger, P.O. Box 699159, Quincy, MA 02269-9159, or by E-mail to his attention at features@ledger.com.

Questions of general interest will be answered in this column. The information in this column is not intended to diagnose individual conditions, and individual replies are not possible. Readers should see their own doctors about specific problems.

Copyright 2001 The Patriot Ledger
Transmitted July 10, 2001