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Geographic Expansion of Lyme Disease Emphasizes Importance of Recognizing Modes of Transmission

The causative bacteria Borrelia burgdorferi was not officially classified un­til 1981, when scientist Wilhelm Burgdorfer discovered that a spirochete carried by ticks was causing Lyme disease. Since then, the number of reports and geographic expansion of Lyme disease have increased dramatically in the United States, and the Centers for Disease Control and Prevention (CDC) included Lyme dis­ease in their top 10 notifi­able diseases in 2012.3 How­ever, Patricia V. Smith, president of the Lyme Disease Association, noted that the extent of Lyme disease in the United States may be underesti­mated in many states be­cause they do not have the money to perform surveillance and identify the extent of the infected tick population.

Lyme disease has also been reported in about 80 countries worldwide, although Robert C. Bransfield, MD, DLFAPA, said that it is unclear wheth­er Lyme disease is endemic in those countries or wheth­er it spread from the north­eastern United States. “It seems like we’re more aware of it, and now that we’re more aware of it, we identify it,” he said. He pointed out that the increased rates of diagnosis may be due in part to greater aware­ness. “In years past, it was called many other things,” he said.

However, Dr. Bransfield noted that there is debate among experts about whether to use a narrow or broad definition for identifying and treating Lyme disease. The diagnostic crite­ria from the CDC are narrow, as their prima­ry purpose is to monitor the national rate of Lyme disease with a high degree of specificity in the diagnosis. For example, the CDC crite­ria do not recognize Lyme disease in patients with late-onset encephalopathy and a positive blood test, and physicians who use the CDC criteria may fail to diagnose Lyme disease in some patients. By contrast, physicians who use more inclusive clinical criteria for probable cases of Lyme disease may initiate treatment in some patients who do not have the disease, with the rationale that long-term risks with Lyme disease outweigh the risks associated with antibiotic therapy.

Experts generally agree about the signs and symptoms in acute phases of Lyme disease, which may include fever, chills, head­ache, fatigue, muscle and joint aches, swollen lymph nodes, and an erythema migrans rash that begins at the site of the tick bite, 3 to 30 days after the bite and spreads gradually. However, the concept of chronic Lyme disease is contro­versial among experts, according to Dr. Shor, and no systematic evidence supports the pres­ence of Borrelia burgdorferi in patients with chronic symptoms after treated Lyme disease.

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