Lyme disease or borreliosis, is an infectious disease. It is caused by bacteria of the genus Borrelia. The disease is carried by ticks which are parasitic on mammals such as mice and deer. In other words, ticks are the vector which transmits the disease.
It is the most common tick-borne infection in the United States. Although Allen Steere realized in 1978 that Lyme disease was a tick-borne disease, the cause of the disease remained a mystery until 1982. It can cause joint swelling, rashes, and neurological disorders. It remains controversial whether if left untreated, Lyme disease can become a chronic condition. 
- A bulls-eye rash, also known as Erythema migrans.
- Cranial nerve palsies
- Myalgias (muscle pain) and arthralgias (joint pain)
- Stiff neck
- "IDSA : Updated Guidelines on Diagnosis, Treatment of Lyme Disease". www.idsociety.org. Retrieved 2018-06-04.
- "Basic Information about Lyme Disease from ILADS". www.ilads.org. Retrieved 2018-06-04.
- "Lyme Disease - Lyme Disease - CDC". www.cdc.gov. 20 December 2018.