FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

RASH CRITICAL TO CORRECT DIAGNOSIS OF LYME DISEASE WHICH IS SPREAD - NOT CAUSED - BY TICKS

Question: I'm concerned about Lyme disease, and I'm also a bit confused. Some say the risks are so high that one should rarely venture out of their house, while others say that the risks are really quite small. We have many deer in our area, and I know this increases the risk for us. What are the risks of getting Lyme disease?

Answer: Lyme disease is caused by a bacterium (Borrelia burgdorferi) which is fairly common in Pennsylvania, New York, North Carolina, Maryland, Georgia, Missouri, Wisconsin, Minnesota and Ohio. This germ must reside inside of other living creatures in order to survive. The deer tick (Ixodes dammini for the technically minded) is responsible for spreading the bacteria and, therefore, Lyme disease from animal to animal, occasionally including humans.

The life cycle of the tick lasts two years and understanding it is integral to understanding Lyme disease. The female tick lays her eggs in the spring. These hatch into larvae which feed once during the summer on the blood of mammals, usually mice. The larvae change (or molt) into young ticks called "nymphs" the following spring and feed once during the summer on mice, dogs, deer, or humans. The nymphs then molt into adult ticks. In the fall they feed on another mammal frequently white-tailed deer. If one of these feedings is on an animal infected with the Lyme disease causing bacteria, the tick will then give the infection to the next animal upon which it feeds. So the tick doesn't cause Lyme disease, but it is responsible for spreading it.

Lyme disease is more common now that it ever has been because of conservation efforts. You see, there are more deer now than there were even at the time our country was founded. The increased human population in the deer and deer tick habitat also makes it likely that an infected deer tick will come in contact with a human instead of a deer.

Humans infected with Lyme disease develop a rash which clears up without treatment, only to appear in another spot. Since 50 percent of Lyme disease victims don't recall being bitten by a tick, this rash is usually a crucial clue in arriving at the correct diagnosis. While the rash is present, or sometimes after it is over, a flu-like illness develops with headache and muscle and joint aches. As the disease progresses over several weeks to months and becomes chronic, 10 to 15 percent of untreated individuals will develop additional serious problems in the nervous system, heart and joints.

The symptoms of chronic Lyme disease often mimic other diseases. Unfortunately, there are no laboratory tests that are both accurate and specific for the condition. Often we physicians must establish the diagnosis by excluding other possible causes of the symptoms. This is unfortunate for many reasons, but particularly because the delay in treatment decreases the chance for total recovery.

The treatment of Lyme disease involves the use of antibiotics which may be taken by mouth, or in some cases by IV only. We once thought that a 10-day treatment was adequate, but now we know that for those who have been ill for some time before therapy is started, it takes at least six weeks and often up to six months worth of antibiotics to treat it effectively.

Lyme disease is potentially a very serious illness. The risk of you actually catching it, depending on where you go in the woods and adjoining meadows, can be high enough to worry about. For example, there were 79 cases reported in Ohio in one recent year, compared to 1,337 in Pennsylvania and 23 in West Virginia. Your county health department should be able to provide information about the risks in your area or the area where you will be vacationing. As you will infer from the statistics, though, the risk is sufficiently low that it shouldn't deter most people from their outdoor activities.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.