Lyme disease is a bacterial infection transmitted by a tick. Lyme disease was first recognized in 1975, after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Conn., and two neighboring towns.
The investigators discovered that most of the affected children lived near wooded areas likely to harbor ticks. They also found that the children's first symptoms typically started in the summer months coinciding with the height of the tick season.
Several of the patients reported having a peculiar skin rash just before developing arthritis symptoms, and many also recalled being bitten by a tick at the rash site.
Further investigations resulted in the discovery that tiny deer ticks infected with a spiral-shaped bacterium or spirochete (which was later named Borrelia burgdorferi) were responsible for the outbreak of arthritis in Lyme. Ordinary "wood ticks" and "dog ticks" do not carry the infection.
The ticks most commonly infected with B. burgdorferi usually feed and mate on deer during part of their life cycle. The recent growth of the deer population in the northeast and the building of suburban developments in rural areas where deer ticks are commonly found have probably contributed to the increasing number of people with the disease.
The number of reported cases of Lyme disease, as well as the number of geographic areas in which it is found, has been increasing. Lyme disease has been reported in nearly all states in this country, although most cases are concentrated in the coastal northeast, Mid-Atlantic States, Wisconsin, and Minnesota, and northern California. Lyme disease is also found in large areas of Asia and Europe. Recent reports suggest that it is present in South America, too.
In addition to causing arthritis, Lyme disease can also cause heart, brain, and nerve problems.
Lyme disease is transmitted through a bite from a specific type of tick. The animals that most often carry these insects are white-footed field mice, deer, raccoons, opossums, skunks, weasels, foxes, shrews, moles, chipmunks, squirrels, and horses. The majority of these ticks have been found in New York, Connecticut, Massachusetts, Maryland, New Jersey, Minnesota, and Wisconsin.
Erythma migrans. Erythema migrans is the telltale rash which occurs in about 70% to 80% of cases and starts as a small red spot that expands over a period of days or weeks, forming a circular, triangular, or oval-shaped rash. Sometimes the rash resembles a bull's-eye because it appears as a red ring surrounding a central clear area. The rash, which can range in size from that of a dime to the entire width of a person's back, appears between three days and a few weeks of a tick bite, usually occurring at the site of a bite. As infection spreads, several rashes can appear at different sites on the body.
Erythema migrans is often accompanied by symptoms such as fever, headache, stiff neck, body aches, and fatigue. These flu-like symptoms may resemble those of common viral infections and usually resolve within days or a few weeks.
Arthritis. After several weeks of being infected with Lyme disease, approximately 60% of those people not treated with antibiotics develop recurrent attacks of painful and swollen joints that last a few days to a few months. The arthritis can shift from one joint to another; the knee is most commonly affected and usually one or a few joints are affected at any given time. About 10% to 20% of untreated patients will go on to develop lasting arthritis. The knuckle joints of the hands are only very rarely affected.
Neurological symptoms. Lyme disease can also affect the nervous system, causing symptoms such as stiff neck and severe headache (meningitis), temporary paralysis of facial muscles (Bell's palsy), numbness, pain or weakness in the limbs, or poor coordination. More subtle changes such as memory loss, difficulty with concentration, and a change in mood or sleeping habits have also been associated with Lyme disease. People with these latter symptoms alone usually don't have Lyme disease as their cause.
Nervous system abnormalities usually develop several weeks, months, or even years following an untreated infection. These symptoms often last for weeks or months and may recur. These features of Lyme disease usually start to resolve even before antibiotics are started. Patients with neurologic disease usually have a total return to normal function.
Heart problems. Fewer than one out of 10 Lyme disease patients develops heart problems, such as an irregular, slow heartbeat, which can be signaled by dizziness or shortness of breath. These symptoms rarely last more than a few days or weeks. Such heart abnormalities generally appear several weeks after infection, and usually begin to resolve even before treatment.
Other symptoms. Less commonly, Lyme disease can result in eye inflammation and severe fatigue, although none of these problems is likely to appear without other Lyme disease symptoms being present.
Lyme disease imitates a variety of illnesses and its severity can vary from person to person. If you have been bitten by a tick and live in an area known to have Lyme disease, see your doctor right away so that a proper diagnose can be made and treatment started