2014, September/October Adirondac Adirondoc
This has been a busy year for Lyme disease in New York State, with the illness beginning to make inroads into the southern foothills of the Adirondacks. Although I covered prevention in this space in July-August 2011, we have had a lot of requests for more information on the disease. I will try to summarize cur – rent information.
What is Lyme disease? Lyme disease is a fascinating condition, caused by Borrelia burgdoeferi, a type of bacterium called a spirochete. Spirochetes cause a variety of other diseases, such as syphilis and leptospirosis. The condition is referred to as a zoonosis, meaning that it is maintained in a reservoir of other animals, in this case mammals such as the white-footed mouse. Unlike some zoonoses, in which infection spreads directly from animal to human, in Lyme disease the spirochete is shuttled back and forth between hosts by ticks, referred to as the vector of infection. Although deer play a role in the tick life cycle (one species is commonly called the “deer tick”), deer are actually not important in the chain of human infection.
If a tick injects spirochete into the human, the bacterium has an incubation period during which it reproduces and establishes itself. This can range from a day to a month, but is typically about a week and a half. Things may be confusing because ticks occasionally transmit another condition (such as anaplasmosis) coincident with Lyme disease. Lyme disease was first described in Connecticut, and the Mid-Atlantic states are the major region in which it occurs. Other areas in the U.S. with Lyme disease include the Midwest and the northern West Coast.
How does Lyme disease appear? Lyme disease is typically described as occurring in three stages, with different body parts affected in each stage. The early localized stage is marked by a distinctive rash, sometimes described as a “bull’s eye”, and called erythema migrans. This develops after the incubation period, often around the area of the tick bite. It is rarely painful or itchy, but patients may have symptoms such as headache or muscle aches.
The early disseminated stage occurs when the spirochete has spread, usually several weeks after the initial infection. This is much more debilitating, with joint or muscle pain, occasional disturbances in the heart rhythm, inflammation of the eye, focal paralysis of parts of the face, and a variety of other manifestations. The rash may recur at this stage, although it may be different in appearance.
Late disease is primarily arthritis, an inflammation of joints such as the knee. In fact, the original description of Lyme disease was as a form of arthritis. Other manifestations such as nerve damage may occur at this stage.
Most patients do not display all these stages. Some may have disease limited to erythema migrans. Alternatively, as many as 20 percent of patients with late disease never had erythema migrans.
How is Lyme disease diagnosed? In the early local stage, the diagnosis is clinical, based upon history and the rash. No other testing is needed, or helpful.
In later stages, the disease is diagnosed by the presence of antibodies to the organism. This is initially determined with a test called EIA, which if positive is confirmed by a Western blot. Once one has had Lyme disease, these tests are generally positive for years. Thus, tests are not useful in gauging success of treatment. The CDC has warned against the use of other, unvalidated testing.
How is Lyme disease treated? Lyme disease is treated with an oral course of a common antibiotic for two to three weeks. Infection of the nervous system requires intravenous therapy.
A final word. For the vast bulk of patients, the above description of Lyme disease applies. There are rare patients who have prolonged symptoms, including profound fatigue. These folks, who clearly have a serious condition, are sometimes said to have “chronic Lyme disease.” Despite commentary to the contrary, there is no consensus on exactly what these individuals have. They clearly do not have persistent infection with spirochete, and there is no place for prolonged courses of oral or intravenous antibiotics.
~ Tom Welch, MD, is professor and chair of pediatrics at Upstate Medical University in Syracuse and an active member of the Wilderness Medical Society. He is a licensed professional guide and a certifying instructor for the Wilderness Education Association, and has guided groups in the Adirondacks, Montana, and Alaska. More information is available at his website and blog: www.adirondoc.com. Leonard Weiner, MD, chief of infectious diseases at Upstate Medical University/Golisano Children’s Hospital, reviewed the article and provided helpful advice.Insects & Spiders