The disease was discovered in 1976 and was named after numerous cases occurred in the city of Lyme, Connecticut, United States. It is currently the most common tick-borne infection in the United States, occurring in 49 states. More than 90% of cases occur along the northeast coast, from Maine to Virginia and in Wisconsin, Minnesota, and Michigan. On the west coast of the United States, most cases occur in the northern states of California and Oregon. Lyme disease also appears in Europe, China, Japan, and the countries of the former Soviet Union.