Definition

Lyme disease is caused by the bacterium Borrelia burgdorferi (Bb). The bacterium is carried by ticks and is transmitted to humans through a tick bite. The disease is named for the town of Lyme, Connecticut. It was in Lyme that the disease was first discovered in 1975, after a series of unexplained cases of arthritis developed.

Description

Lyme disease is a vector-borne disease. A vector is an organism that carries a disease from one organism to another. In this case, the vector is the tick. The tick carries the bacterium B. burgdorferi in its blood and saliva. When the tick bites a human, it leaves some of its saliva, along with the bacterium, in the human's bloodstream. The bacterium begins to reproduce and spread. Eventually it causes the symptoms of Lyme disease.

Lyme disease accounts for about 90 percent of all reported vector-borne diseases in the United...