San Mateo County: Tick Surveillance

Entomology Report June 2005, San Mateo County Mosquito Abatement District

The District has begun conducting surveillance for Rocky Mountain spotted fever (RMSF) in conjunction with state and county health department personnel. This disease is caused by the bacteria Ricketsia rickettsii and transmitted by ticks. Symptoms of the disease include sudden onset of fever, headache, and muscle pain, followed by development of a rash. Two residents of San Mateo County have been diagnosed with spotted fever group rickettsia in the past 3 years. The disease can be transmitted by 2 species of ticks found locally (Dermacentor variablis and Dermacentor occidentalis). Therefore, surveillance is being conducted to assess the public health risk in the county for RMSF. Unlike the western black-legged tick (vector of Lyme disease), these ticks are active during summer months.

Over 100 ticks were collected from Sawyer Camp trail and Edgewood Park in June and are currently being tested by CDHS for spotted fever group rickettsia.