By: P. Michael Shattuck, M.D. – Community Health Network Family Physician
Lyme disease is common in our area and statistics suggest that the incidence is increasing. Lyme disease got its name because it was first identified in the town of Lyme, Connecticut. Lyme disease is an infectious disease caused by a bacterium that is transmitted by a tick. The bacterium is a spirochete called Borrelia Burgdorferi that can live in the gut of ticks. If a tick that is carrying the bacteria attaches to the skin and feeds, the bacteria can be introduced into the skin and cause infection. It is felt the tick needs to be attached more than 36 hours to transmit disease. Deer ticks, or black legged ticks, are known to be carriers. The percentage of deer ticks carrying the agent seems to be increasing with reports of about 50 % carrier rate in our area. Other types of ticks are not known to carry the Lyme disease bacteria. There are several diseases that can be transmitted by ticks. This article will focus on Lyme disease.
Lyme disease can be difficult to diagnose. It may present with vague symptoms. Sometimes the person affected may not even know that they were bitten by a tick. The initial phase of the disease classically is associated with “flu like symptoms” including fever, headache, muscle aching, fatigue, and rash. The rash develops several days to a week after the bite and can grow slowly over a few weeks. The rash is generally reddish pink and can cover a large area. It is often referred to as erythema chronica migrans or ECM. However, the rash may only occur in about half the cases. Diagnosis in the early stage is based on the clinical symptoms and exam since blood tests may not be positive yet.
In the later phases of the disease, which can be weeks or months later, secondary problems can present involving the joints, heart, and nervous system. These symptoms can also be vague and can overlap other diseases making the diagnosis challenging. The bacterium is very hard to grow in the laboratory so in the later phases of the disease clinicians tend to depend on blood tests that measure antibody levels to the Lyme bacteria. The tests detect the antibodies formed by the body toward the Lyme bacteria indicating the bacterium was present. Currently the blood is tested in a two-step protocol. The first step will detect antibodies that could be due to Lyme infection. If that test is negative it is a good indication infection is not present. However, if the test is positive, a second more specific test is done to confirm whether the Lyme specific antibodies are present. To be a positive test, both parts need to be positive. Once the antibodies are present they can stay in the blood for many years. To make things even more complicated, even if both parts of the test are positive that still does not confirm with 100% certainty that active Lyme disease is present. A false positive test can be due to a previous infection, previous vaccination for Lyme disease (the Lyme vaccine is no longer available), or a lab error. So, to make the diagnosis of late stage disease, the clinical syndrome and a positive two stage blood test are required.
Once the diagnosis is established, the disease is treated with antibiotics generally requiring several weeks of medication. Treatment is more effective if started early in the course of the illness. Generally the infection can be treated with antibiotics effectively.
The key to preventing Lyme disease is to avoid ticks. If a tick attaches, remove it immediately. If the tick has been attached for over 36 hours, you think it was a deer tick, and it was a tick contracted in Wisconsin you may be a candidate for a prophylactic antibiotic. Also, you should seek medical attention if there is a growing rash, fever or other classic symptoms. Lyme disease is a health concern in the warmer months in Wisconsin when ticks are active. Try to avoid ticks but seek medical attention if you think you have a significant exposure or symptoms. Stay healthy my friends.