Why bother inspecting for ticks? First of all, they are nasty little creatures. From my perspective, any creature wanting some of my blood is nasty. Secondly, ticks carry diseases with them. When they burrow into your skin to find a small blood vessel (capillary) they will spit out anticoagulants. Anticoagulants prevent the blood from clotting. If the blood clots after they have placed a hole in your capillary then the tick will not be able to get its blood meal. The anticoagulants aren't the only thing that the tick gives us. Sometimes along with the anticoagulant comes a microorganism. To see how many tick-borne diseases (diseases transmitted by ticks) there are in the United States click here.
One microorganism that causes a large number of people to get sick is Borrelia burgdorferi. This spiral-shaped bacteria usually causes flu-like symptoms and a rash at the site of the tick bite. Arthritis can develop in some people weeks to months after the initial symptoms have gone away. Most of these people can eliminate their arthritis with antibiotic treatment but about 10 percent of these arthritic patients do not get better with antibiotic treatment.
This has been a puzzling problem for a number of years. A recent article in Science (July 31, 1998; Volume 281 No. 5377, pg.631-632 and 703-706) indicates that a protein from Borrelia burdorferi may be triggering these arthritic patients to mount an immune response against their own bodies. For a number of years now, scientists have known that people with a particular protein on the immune cells of their body will develop arthritis after being infected with Borrelia burgdorferi. These people have an Human Lymphocyte Antigen (HLA) called DRB1*0401.
HLA proteins help our bodies to determine whether it should mount an immune response to foreign substances. People with HLA DRB1*0401 are also more likely to develop rheumatoid arthritis.
The HLA protein DRB1*0401 binds to a Borrelia burgdorferi protein called Osp A (Outer Surface Protein A). The portion of Osp A that is bound to DRB1*0401 is identical to a protein found on human cells called hLFA-1. When immune cells were removed from the joints of 11 patients with antibiotic resistant Lyme arthritis the scientists found the cells from nine of those patients reacted to both Osp A and hLFA-1.
The current hypothesis is that Borrelia burgdorferi will turn on these immune cells after binding to Osp A. Unfortunately, once these immune cells are activated they not only destroy the bacteria but will then also
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