skip to main content

Public Health - Seattle & King County

Ticks and Tick-borne diseases

Tick

Reports of tick-borne disease in Washington state are relatively few in comparison to some areas of the United States. Though tick-borne disease may not be common, the severity of these diseases generates public concern and questions.


Tick-Borne Relapsing Fever (TBRF)

Tick-borne relapsing fever is a disease caused by bacteria called Borrelia. The bacteria are spread by soft (argasid) ticks that are infected with the bacteria from feeding on infected wild rodents. The disease is characterized by relapsing (recurrent) periods of fever and other symptoms lasting for 2 to 7 days, disappearing for about 4 to 14 days, and then reoccurring. This cycle may go on for weeks if treatment is not started.


Lyme Disease

Lyme Disease is caused by a bacterium called Borrelia burgdorferi, which is transmitted by the bites of infected ticks. Ticks become infected by feeding on infected rodents and deer. It is the most common tick-borne disease in the US. Infections acquired in Washington State appear to be rare, but the disease is a concern in the East and Midwestern states, and in some areas of California and Oregon. The first symptom is usually an expanding red rash which starts at the site of the tick bite. Fever, headache, muscle aches and joint pain may also occur. If it goes untreated, later symptoms can include recurring rash, joint pain, heart disease and nervous system disorders.