Tens of thousands of Lyme disease cases are reported in the United States each year, according to the Centers for Disease Control and Prevention. However, the actual number of infections is likely several times higher. In fact, Lyme disease is now the most common vector-borne illness in the country. But nobody actually knows how common it is.

Recent studies by the CDC are beginning to shed light on why that is.

I asked Dr. Alison Hinckley, a CDC epidemiologist, what the significance of these studies is for the ordinary person.

“The bottom line,” she said, “is there are different data sources used to answer questions about Lyme disease epidemiology and trends. Taken together, the data demonstrate that Lyme disease is a significant and growing public health threat. The numbers indicate a large burden on the health care system, a threat to public health, and the need for more effective prevention measures.”

Lyme disease is a tick-borne illness primarily transmitted by black-legged ticks of the Ixodes genus. First identified in 1975 in Lyme, Connecticut, it has since spread geographically across the United States. People contract Lyme disease after being bitten by a tick infected with the bacterium Borrelia burgdorferi. Early symptoms often include fever, chills, a characteristic rash known as erythema migrans and muscle or joint pain. If left untreated, Lyme disease can lead to more severe complications, such as facial paralysis, heart rhythm disturbances, arthritis and inflammation of the brain and spinal cord.

Understanding the gap between reported cases and the true disease burden requires distinguishing between surveillance data and the broader scope of undiagnosed or unreported cases.  (See link for article)

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**Comment**

Thankfully the article mentions that surveillance is a problem due to the fact there must be laboratory evidence of infection as well as clinical information to confirm diagnosis.  How can a test that misses up to 90% of cases be seriously used to determine cases of infection?