Lyme disease is a bacterial disease transmitted by an arthropod. The arthropod that carriers this disease is a tick. A couple of the most common are the black-legged (deer tick) and the western black-legged ticks (2). The black-legged ticks live in north central and north eastern United States, and their genus species name is Ixodes scapularis (2). The western black-legged ticks live on the Pacific coast, and their genus species name is Ixodes pacific (2). There are over two hundred species of Ixodes and many will transmit Lyme disease to humans (5). They feed by inserting their mouth into the skin of a host and slowly take in blood (2). Most likely they transmit the infection after feeding for two or more days (2).
Some of the usual reservoirs are living humans, ticks, rodents, mice, and deer (1). Lyme disease is the most common tick-transmitted disease in the USA (4).
Borrelia burgdorferi is the etiologic agent it is a type of spirochete (3). Spirochetes are long, thin, spiral-shaped bacteria (3). The bacterium can be aerobic or microaerophilic spirochete (1). The morphology of B. burgdorferi is gram-negative spiral (1). This pathogen can cause problems with joints, bones, nervous system, and heart (1). A gram stain can be performed to help identify the bacterium.
It is a popular misconception that Lyme disease was discovered in the late 1970's in Lyme, Connecticut (3). However, medical literature is actually rich with more than a century of writing about the condition, although most of it has been published only in Europe (3). The first record of a condition associated with Lyme disease dates back to 1883 in Berslau, Germany, where a physician named Alfred Buchwald described a degenerative skin disorder now known as acrodermatitis chronica atrophicans (ACA) (3). In 1909, a physician named Arvid Afzelius presented research about an expanding, ring like lesion he had observed (3). Afzelius published his work twelve years later and speculated that the rash came from the bite of an Ixodes tick (3). In 1970, for the first time an incidence of EM (erythema chronicum migrans) in the US was reported by Rudolph Scrimenti (3). In 1976, the first US clustering case of Lyme disease was reported (3). In the early 1980's, an entomologist by the name of Willy Burgdorfer, MD, Ph.D., was investigating outbreaks of Rocky Mountain spotted fever (3). Two other research scientists collaborated in gathering and testing ticks for disease-causing pathogens (3). During the research, attention shifted from dog to black-legged ticks and in 1981, one of the batches of ticks yielded something dramatically new (3). Burgdorfer noticed an embryonic form of parasite in the body fluid of two of the ticks (3). He took a very close inspection of the ticks and found poorly stained, sluggish spirochetes (3). Within a year, the spirochetes had been named Borrelia Burgdorferi (Bb), in his honor, and definitely identified as the causative agent of Lyme disease (3). Dr. Burgdorfer was the partner in the successful effort to culture the spirochetes, along with Alan Barbour, MD (3).
The first stage of Lyme disease is an annular skin rash named erythema chronicum migrans or for short ECM (1) or EM (3). ECM is a unique skin lesion, a red ring with a white center also known as the Bull's eye rash (1). This rash grows larger with time (1). In the second stage the infected human can have many different symptoms some of the possible signs are: fever, chills, malaise, fatigue, headache, joint pain, meningitis, sore throat, hepatitis, and Bell's palsey (1). In the third stage the microbe can now have caused arthritis, neurological changes, acute confusion, dermatitis, and/or leukocytosis (1). After four weeks individuals with the illness usually have abnormal blood test (4).
Much of the symptomology may be due to the host immune response (1). Borrelia burgdorferi are able to move around the body thru the bloodstream and between tissues (3). The bacterium can also invade tissue, replicate, and leave the cell - destroying the cell as it emerges (3). Sometimes as the bacterium emerges the cell wall collapses around the bacterium, forming a "cloaking device" (3). This action may aid the bacteria's ability to hide from the immune system (3). It has been postulated that B. burgdorferi undergoes antigenic variation to evade clearance by the host, but this has not been proven (1).
Treatment varies and depends on how early a diagnosis is made and the organ system(s) involved (3). Penicillin and tetracycline (1) are medications that can be taken to treat the disease. All stages may be cured with antibiotics; however, late neurologic or arthritic involvement may not improve (4). The arthritic complaints that may affect individuals are best evaluated and treated by a rheumatologist (4). They also serve as consultants to primary care physicians in questions pertaining to the treatment of Lyme disease (4).
Whenever possible, avoid entering areas that are likely to be infected with ticks, particularly in spring and summer when nymphal ticks feed (2). If you are going to be in areas that are tick infested wear light-colored clothing, long-sleeved shirts, and tuck pants into boots (2). The transmission of B. burgdorferi from an infected tick is unlikely to occur before thirty-six hours of tick attachment (2) so the tick needs to be removed as soon as possible.
As of Feb. 25, 2002, the manufacturer announced that the LYMErix Lyme disease vaccine would no longer be commercially available (2). Guidelines for the use of LYMErix is recommended by the Advisory Committee on Immunization Practices (ACIP) they are published in the "Morbidity and Mortality Weekly Report" series, June 4, 1999 (2). Lyme vaccine is made from lapidated rOspA of Borrelia burgdorferi sensu stricto (6). The rOspA protein is expressed in E. coli and purified (6). Another producer is using a lapidated and purified rOspA preparation based on Borrelia burgdorferi B isolate (6).
References:
1. "Bugs" Index-Organisms. 04-13-99. URL: http://www.medinfo.ufl.edu/year2/mmid/bms5300/bugs/borburg.html accessed on 04-25-02.
2. CDC Lyme Disease Home Page. 09-21-01. URL: http://www.cdc.gov/ncidod/dvbid/lyme/index.htm accessed on 04-25-02.
3. About Lyme disease bacterium, where it came from, and treatment. URL: http://www.lyme.org/otherdis/ld_bacterium.html accessed on 04-30-02.
4. American College of Rheumatology. 2000. URL: http://www.rheumatology.org/patients/factsheet/lyme.html accessed on 04-30-02.
5. Parasites and Parasitological Resources. URL: http://www.biosci.ohio-state.edu/~parasite/ixodes.html accessed on 04-30-02.
6. World Health Organization. 2001. URL: http://www.who.int/vaccines-diseases/safety/infobank/lymedis.shtml accessed on 04-30-02.