Treating Lyme disease rests heavily on identifying its bacterium as quickly as possible and administering antibiotics before it has time to spread. A recent study out of the University of Arizona in Tucson found that the bulls-eye shaped rash indicative of Lyme disease could explain the relationship between the body’s immune system response and how the disease-carrying bacteria is spread.

Lead researcher, Dr. Charles Wolgemuth, and graduate student Dhruv Vig have a developed a simple mathematical equation based on our immune system’s interaction with disease-causing bacteria. The immune system’s response to bacteria often ends with the appearance of a rash and spread of the infection. At the start of its development, the rash is relatively small, and the immune system responds by attacking the area where it's strongest — the center.

Unfortunately, as our immune system eats away at the center of the rash, its edges continue to spread, activating more immune responses. As the rash grows, the center becomes less inflamed until bacteria resurfaces in this area, ending with the erythema migrans’ definitive bulls-eye shape. A future model of the research team’s equation could predict the disease’s concentration through a change in immune cell populations.

"Our findings are important because they connect how the rash looks with the behavior of the bacteria in our body," Wolgemuth, from the University of Arizona in Tucson, said in a statement. "The model that we have developed can be used to predict how the bacteria move through our bodies and how they are affected by therapeutics. Therefore, it is likely that this model will also be applicable to understanding syphilis, as well as potentially other bacterial infections."

According to the Centers for Disease Control and Prevention, Lyme disease is a tick-borne illness that is caused by the bacterium Borrelia burgdorferi. People usually develop Lyme disease after being bit by a blacklegged tick. Symptoms can include fever, headache, fatigue, and skin rashes called erythema migrans. Lyme disease is the most common vector-borne illness, or an illness transmitted by mosquitos, ticks, and fleas, especially in northeast and upper Midwest states, including Vermont, New Hampshire, New York, New Jersey, Wisconsin, and Minnesota.  

Treating Lyme disease currently depends on identifying the bacteria and administering antibiotics such as doxycycline, amoxicillin, or cefuroxime axetil. However, patients who do not receive appropriate treatment through antibiotics or receive it too late have a 10 to 20 percent risk of being diagnosed with post-treatment Lyme disease syndrome (PTLDS). Tracking the rash’s progression and how it affects our immune response could be the most effective method for treating Lyme disease.

 

Source: Vig D, Wolgemuth C. Spatiotemporal Evolution of Erythema Migrans, the Hallmark Rash of Lyme Disease. Biophysical Journal. 2014.