What disease is caused by the bacterium Borrelia burgdorferi?

Lyme disease is the disease caused by the bacterium Borrelia burgdorferi. It is a tick-borne infection that can affect the skin, joints, nervous system, and heart if it is not treated.

In North America, Borrelia burgdorferi is transmitted mainly by infected blacklegged ticks of the genus Ixodes. The smallest nymphal ticks are responsible for many infections because they are about the size of a poppy seed and can go unnoticed. Small mammals, especially mice, help maintain the bacterium in nature, while deer support tick populations but generally do not infect ticks with Borrelia.

An expanding rash called erythema migrans is a well-known early sign, although it does not appear in every case. Fever, fatigue, headache, facial-nerve weakness, arthritis, and heart-rhythm problems can occur at different stages.

The bacterium was named after Willy Burgdorfer, who identified it in 1981. Lyme disease takes its common name from Lyme, Connecticut, where a cluster of unexplained arthritis cases helped bring the illness to medical attention in the 1970s.