What is Lyme Disease?

05 March 2010
Last Updated: 19 June 2016
What Is Lyme Disease?
Lyme disease is an infection caused by the bacteria called Borrelia burgdorferi (Bb).  There are approxamitly 300 strains of Borrelia burgdorferi (Bb), with about 100 strains prevelent in the USA. 


Image Borrelia burgdorferi (Lyme disease bacterium) in cyst form.
Image courtsey of Ed Masters.
How is Lyme disease transmitted?
In the USA, the bacteria are transmitted to people and animals by the bite of an infected blacklegged tick, Ixodes scapularis, commonly called the deer tick, and Ixodes pacificus (western black legged tick) in the West. Although other types of ticks such as the Dermancentor variabilis (american dog) and some insects have been shown to carry the Lyme bacteria, to date, transmission of Lyme through those vectors has not been proven.  Note: Other tick borne disease have been transmitted though the blood supply. 
The bacteria can also be passed through the placenta of a pregnant woman to the fetus—congenital transmission.
The DNA of the bacteria has been found in breast milk, but no transmission has been proven to date in humans.
The Lyme bacteria have been proven to survive blood banking conditions; however, to date, no transmission has been proven through blood transfusions in humans. Studies have shown transmission through this route in mice in the lab.
There is no proof to date that Lyme is sexually transmitted, although some preliminary studies have found PCR positives for the DNA of the Lyme bacteria in semen and in cervical tissue. These findings do not prove sexual transmission, but some physicians feel because the Lyme and syphilis spirochete (bacteria) are similar, Lyme may be sexually transmitted.
Lyme disease is found in approximately 80 plus countries worldwide, although different types of ticks and different strains of bacteria may be involved. In the USA there are over 300,000 new cases of Lyme disease contracted each year.   Many of those cases will include co-infections. 
Where can Lyme disease be found in the body?
Lyme is a multi-systemic disease, and the Lyme disease bacterium, Borrelia burgdorferi (Bb), may be found in many different organs, although it is often difficult to test for and to culture. Here is a picture which shows Bb in the human colon.
Image Borrelia burgdorferi (Lyme disease bacterium) in the Human Colon.
Image Courtesy of Martin Fried, MD.
A Lyme disease patient's colon biopsy specimen. The patient had abdominal pain and blood in the stool (Dieterle stain-magnification x522)

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