[HideMe]Lyme disease

Lyme disease is a tickborne disease caused by the bacteria Borrelia burgdorferi.  It was first identified in California in 1978 from a Sonoma County hiker.  While incidence of Lyme disease (number of cases adjusted per population) is highest in the northwestern part of the state, human cases have been reported from many regions of California.

In California, the western black-legged tick, Ixodes pacificus, is the only tick that transmits Lyme disease to people.  This tick has three life stages, a larval, nymphal and adult stage.  People become infected with Lyme disease via the bite of an adult female or a nymphal western-black legged tick.  Infection prevalences of B. burgdorferi in the western black-legged tick are approximately 1-2% in adults, 2-15% in nymphs, and 0% in larvae.  People are at highest risk of acquiring Lyme disease from nymphal ticks due to their small size and higher infection prevalence. Lyme disease is most commonly reported in spring and early summer in California, when nymphal ticks are most abundant.  Adult western black-legged ticks are most active in fall and winter.

For more information on Lyme disease, please visit the California Department of Public Health website at: http://www.cdph.ca.gov/healthinfo/discond/Pages/LymeDisease.aspx

Anaplasmosis

Human granulocytic anaplasmosis (HGA) is an infection caused by the bacteria Anaplasma phagocytophilum. HGA bacteria infect the whte blood cells of their hosts, specifically a group of cells called granulocytes. People acquire HGA in California, when they are bitten with a western black-legged tick (Ixodes pacificus) infected with HGA bacteria.

For more information on Anaplasmosis, please visit the California Department of Public Health http://www.cdph.ca.gov/healthinfo/discond/Pages/Anaplasmosis.aspx

Rocky Mountain Spotted Fever

Rocky Mountain spotted fever (RMSF) is a serious disease caused by Rickettsia rickettsii bacteria and transmitted to people by ticks, principally the Rocky Mountain wood tick, Dermacentor andersoni and the American dog tick Dermacentor variabilis. In California, RMSF is a rare disease, with only 1 to 3 cases reported per year; most cases are reported from the south Atlantic region of the United States.

Additional information on RMSF can be found at the Center for Disease Control and Prevention website:

http://www.cdc.gov/ncidod/dvrd/rmsf/index.htm

as well as at the California Department of Public Health website: http://www.cdph.ca.gov/healthinfo/discond/Pages/RockyMountainSpottedFever.aspx

Tickborne Relapsing Fever

Tickborne relapsing fever (TBRF) is a bacterial disease transmitted to people by soft ticks in the genus Ornithodors. TBRF is a rare disease in California with between 1 and 8 cases reported per year, generally during the summer months. People are at risk of contracting TBRF when they sleep in rustic mountain cabins that are infested with wild rodents. The soft ticks that transmit TBRF feed rapidly; most people who contract TBRF have no recollection of a tick bite.

For more information on Tickborne relapsing fever, please visit the California Department of Public Health website: http://www.cdph.ca.gov/healthinfo/discond/Pages/Tick-BorneRelapsingFever.aspx