Lyme disease is an infectious condition spread through the bite of certain ticks. It frequently causes fatigue and headache and can progress to arthritis and other complications. 

Lyme disease affects about eight out of every 100,000 Americans annually, according to the Centers for Disease Control and Prevention (CDC). It is the leading tick-borne disease in North America and Europe. In the United States, it is most common in the Northeast and parts of the Midwest, but in a typical year it occurs in all but a few states.

In addition to fatigue and headache, indicators of Lyme disease can include fever, joint pain and a red rash. Symptoms vary according to the disease's level of advancement.

Lyme disease is often difficult to diagnose. Symptoms may mimic those of other conditions. As a result, several types of testing, such as blood tests and in some cases a spinal tap, may be performed.

Depending on the phase of infection, oral or intravenous antibiotics are administered. Lyme disease may be successfully treated at any stage, though treatment is most effective when diagnosis comes early. Occasionally, post-Lyme disease syndrome can occur when symptoms persist long after treatment or eradication has ended.

Left untreated, Lyme disease can cause complications such as meningitis, encephalitis, partial paralysis, cognitive defects or heart problems. In rare cases it can be fatal. In addition, patients with Lyme disease may be infected with two other potentially serious diseases transmitted by the same tick: human granulocytic anaplasmosis (HGA) and babesiosis.

A vaccine was once available to help prevent people from getting Lyme disease. However, its sale was discontinued in 2002 amid concerns of significant complications in some users. Preventive measures remain the most effective methods of reducing exposure. These steps include using repellant with DEET, wearing proper clothing and inspecting the skin for ticks.