Lyme Disease
Lyme disease (LD) is an infection caused by Borrelia burgdorferi, a type of bacterium called a spirochete (pronounced spy-ro-keet) that is carried by deer ticks. An infected tick can transmit the spirochete to the humans and animals it bites. Untreated, the bacterium travels through the bloodstream, establishes itself in various body tissues, and can cause a number of symptoms, some of which are severe.
LD manifests itself as a multisystem inflammatory disease that affects the skin in its early, localized stage, and spreads to the joints, nervous system and, to a lesser extent, other organ systems in its later,
disseminated stages. If diagnosed and treated early with antibiotics, LD is almost always readily cured. Generally, LD in its later stages can also be treated effectively, but because the rate of disease progression and individual response to treatment varies from one patient to the next, some patients may have symptoms that linger for months or even years following treatment. In rare instances, LD causes permanent damage.
Although LD is now the most common arthropod-borne illness in the U.S. (more than 150,000 cases have been reported to the Centers for Disease Control and Prevention [CDC] since 1982), its diagnosis and treatment can be challenging for clinicians due to its diverse manifestations and the limitations of currently available serological (blood) tests.
Symptoms
The spirochetal agent of Lyme disease, Borrelia burgdoferi, is transmitted to humans through a bite of a nymphal stage deer tick Ixodes scapularis (or Ixodes pacificus on the West Coast). The duration of tick attachment and feeding is a key factor in transmission. Proper identification of tick species and feeding duration aids in determining the probability of infection and the risk of developing Lyme disease.
How long has that tick been feeding on you?
The early symptoms of LD can be mild and easily overlooked. People who are aware of the risk of LD in their communities and who do not ignore the sometimes subtle early symptoms are most likely to seek medical attention and treatment early enough to be assured of a full recovery.
The first symptom is usually an expanding rash (called erythema migrans, or EM, in medical terms) which is thought to occur in 80% to 90% of all LD cases. An EM rash generally has the following characteristics:
* Usually (but not always) radiates from the site of the tickbite
* Appears either as a solid red expanding rash or blotch, OR a central spot surrounded by clear skin that is in turn ringed by an expanding red rash (looks like a bull's-eye)
* Appears an average of 1 to 2 weeks (range = 3 to 30 days) after disease transmission
* Has an average diameter of 5 to 6 inches
(range = 2 inches to 2 feet)
* Persists for about 3 to 5 weeks
* May or may not be warm to the touch
* Is usually not painful or itchy
Ticks will attach anywhere on the body, but prefer body creases such as the armpit, groin, back of the knee, and nape of the neck; rashes will therefore often appear in (but are not restricted to) these areas. Please note that multiple rashes may, in some cases, appear elsewhere on the body some time after the initial rash, or, in a few cases, in the absence of an initial rash.
Around the time the rash appears, other symptoms such as joint pains, chills, fever, and fatigue are common, but they may not seem serious enough to require medical attention. These symptoms may be brief, only to recur as a broader spectrum of symptoms as the disease progresses.
As the LD spirochete continues spreading through the body, a number of other symptoms including severe fatigue, a stiff, aching neck, and peripheral nervous system (PNS) involvement such as tingling or numbness in the extremities or facial palsy (paralysis) can occur.
The more severe, potentially debilitating symptoms of later-stage LD may occur weeks, months, or, in a few cases, years after a tick bite. These can include severe headaches, painful arthritis and swelling of joints, cardiac abnormalities, and central nervous system (CNS) involvement leading to cognitive (mental) disorders.
Treatment
Early treatment of LD ( within the first few weeks after initial infection) is straightforward and almost always results in a full cure. Treatment begun after the first three weeks will also likely provide a cure, but the cure rate decreases the longer treatment is delayed.
Doxycycline, amoxicillin and ceftin are the three oral antibiotics most highly recommended for treatment of all but a few symptoms of LD. A recent study of Lyme arthritis in the New England Journal of Medicine indicates that a four-week course of oral doxycycline is just as effective in treating late LD, and much less expensive, than a similar course of intravenous Ceftriaxone (Rocephin) unless neurological or severe cardiac abnormalities are present. If these symptoms are present, the study recommends immediate intravenous (IV) treatment.
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