Friday, April 22, 2011

Lyme Disease

Borrelia borgdorferi spirochete causes most Lyme disease in the United States. Borrelia burgdorferi is a parasite transmitted by infected ticks from deer, mice, and other small rodents that harbor the spirochete. Often these animals have a large number of the bacterium but display no symptoms. A human infected by this bacterium has widespread problems in many organ systems. The difference is the way the spirochete is transmitted and the way the immune system reacts to this bacterium. In humans, the Lyme organism has learned to survive very well.

As early as the tick bite itself, Borrelia burgdorferi can bypass the immune system in several ways. The tick has several agents in its saliva that coat the invading spirochetes, protecting them as they enter the body through the skin. This allows the bacterium to go unrecognized as a foreign invader. Therefore the immune system goes without "seeing" them. The immune system of someone infected with Borrelia burgdorferi may go for weeks without producing antibodies. Borrelia has flagellum which enables it to invade tissues and thick mucous that normally most other bacteria would not be able to invade. The flagellum excites the immune system. The immune system then recognizes the bacterium is present and responds by producing antibodies. Borrelia is able to go through metamorphosis by changing its proteins on its outer cell wall and the immune system cells are not able to recognize the bacteria. The immune system typically uses cell wall proteins to detect a foreign invader, and develop specific antibodies to mount a coordinated immune attack. As a result of the transformation of the spirochete the immune cells know the bacterium is there but the bacterium is disguised to fit in. The immune system sends in all available immune cells to destroy everything in the area, and in consequence body tissue is destroyed.


Neutrophils, monocytes, macro-phages, and dendritic cells are the immune cells that try to fight the invaders, but are unsuccessful. Massive immune cells that invade joint tissue take up space and release toxic compounds in an effort to destroy the spirochete. These cells especially neutrophils release proteins and small molecules called cytokines, which cause further inflammation. The prolonged immune response causes inflammation trying to fight the Borrelia burgdorferi infection, which in turn causes most of the symptoms of Lyme disease, including joint inflammation, skin changes, persistent arthritis and neurological problems. The way the body responds to the Borrelia spirochete does more harm than good.


Lyme disease can be hard to diagnose because it mimics the symptoms of other illnesses. There is no definitive test for Lyme disease. If a person is displaying symptoms and suspect a tick bite, they can expect their doctor to possibly order tests such as the ELISA test, Western blot test, and PCR test. Antibiotics are the primary treatment for Lyme disease depending on the patient and the stage of the disease. The antibiotics commonly used are doxycycline and amoxicillin. Scientists are hoping to discover treatments that can modulate these painful immune system effects or getting rid of Lyme disease completely.

References:
http://www.marvistavet.net/html/body_lyme_disease.html
http://www.unmedu/altmed/lyme-disease-000102.htm
http://www.lymediseaseblog.com/how-lyme-disease-affects-immune-system/


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