Lyme Disease

Lyme disease or Lyme borreliosis is an infectious tick-borne disease, caused by the Borrelia spirochete, a gram-negative microorganism.

Lyme disease is so named because it is generally believed to have first been observed in and around Old Lyme and Lyme, Connecticut in 1975. Before 1975, elements of Borrelia infection were also known as "tick-borne meningopolyneuritis", Garin-Bujadoux syndrome, Bannwarth syndrome or sheep tick fever. It is transmitted to humans by the bite of infected ticks.

History
The disease was first documented as a skin rash in Europe in 1883. Over the years, researchers there identified additional features of the disease, including an unidentified pathogen, its response to penicillin, the role of the Ixodes tick (wood tick) as its vector, and symptoms that included not only the rash but additional ones that affected the nervous system.

Researchers in the US had been aware of tick infections since the early 1900s. For example, an infection called tick relapsing fever was reported in 1905, and the wood tick, which carries an agent that causes Rocky Mountain spotted fever, was identified soon after. However, the full syndrome now known as Lyme disease, was not identified until a cluster of cases thought to be juvenile rheumatoid arthritis occurred in three towns in southeastern Connecticut, in the United States. Two of these towns, Lyme and Old Lyme, gave the disease its popular name.

In 1982 a novel spirochete was isolated and cultured from the midgut of Ixodes ticks, and subsequently from patients with Lyme disease. The infecting agent was first identified by Jorge Benach, and soon after isolated by Willy Burgdorfer, a scientist at the National Institutes of Health who specialized in the study of spirochete microorganisms. The spirochete was named Borrelia burgdorferi in his honor. Burgdorfer was the partner in the successful effort to culture the spirochete, along with Alan Barbour.

Symptoms
Lyme disease has many symptoms, but skin symptoms, arthritis and various neurological symptoms are usually present. Conventional therapy is with antibiotics.

Acute (early) symptoms
"bull's-eye" rash (erythema migrans) - a circle or ring of inflamed skin surrounding the initial tick bite) or papular (raised) rash
fever
malaise
fatigue
headache
muscle and joint aches in large joints
sore throat
sinus infection
paralysis - usually associated with Lyme meningitis or Rocky Mountain spotted fever.
The incubation period from infection to the onset of symptoms is usually 1–2 weeks, but can be much shorter (a couple of days), or even as long as one month. However, it is possible for an infected person to display no symptoms, or display only one or two symptoms, which can make diagnosis difficult.

Diagnosis
The most reliable method of diagnosing Lyme disease is a clinical exam by an experienced practitioner. Supportive data by laboratory tests is never well-advised due to the known non-validity of the CDC's current testing criteria. In cases where the "bull's eye" rash is present in conjunction with a fever or the patient saw the tick, treatment can begin without any further tests. The "bull's eye" rash only occurs in a small percent of all infections. The rash is not always seen as bullseye and sometimes can be a papule the size of small coin. Sometimes the tick bite can leave no rash at all.

The serological laboratory tests available are the Western blot and ELISA, but neither is a reliable indicator: test results vary between labs and within the same lab, sero-negative results are frequent. It is estimated that about a quarter of all infections don't register on any antibody test, and hence empirical treatment is occasionally warranted if the clinical suspicion remains high despite negative serology.

Polymerase chain reaction (PCR) tests for Lyme disease may also be available to the patient. A PCR test attempts to detect the genetic material (DNA) of the Lyme disease spirochete, where as the Western blot and ELISA tests look for antibodies to the organism. PCR tests are rarely susceptible to false-positive results but can often show false-negative results.

In cases of chronic Lyme disease, diagnosis is often clinical and must take all factors into account (tick bite exposure, symptom history, etc.). Positive diagnosis will continue to be problematic until a more reliable test is developed.

Prognosis
The severity and treatment of Lyme disease can be complicated by simultaneous infection with other tick-borne diseases, also known as coinfections, bacterial load and immune suppression in the patient. The disease is rarely fatal in and of itself. Chronic Lyme disease can cause severe and possibly lifelong disability and morbidity.

Prevention
The best prevention involves avoiding areas in which ticks are found and can reduce the probability of contracting Lyme disease.

A vaccine against a North American strain of the spirochetal bacteria was available between 1998 and 2002. When taking it off the market, the manufacturer cited poor sales, though some people believe that the actual reason was that the vaccine was not safe or effective at all. [2].

Treatment
Traditional treatment of acute Lyme disease usually consists of a minimum two-week to one-month course of antibiotics.