Ticks are the vectors of a large number of disease-causing agents in California. While Lyme disease is by far the most common tickborne disease of people in the United States and California, ticks also transmit the organisms that cause tickborne relapsing fever, Rocky Mountain spotted fever, tularemia, anaplasmosis, human ehrlichiosis, and babesiosis. In addition, people and domestic animals can develop tick paralysis following a tick bite.
Photo credit Edman/McClelland Collection

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
The following table contains the results of tests for evidence of Borrelia infection in ticks collected in California in 2008. The tests were conducted by the California Department of Public Health, Vector-Borne Disease Section (CDPH-VBDS), and by the United States Army Center for Health Promotion and Preventive Medicine - West (US Army).
|
County
|
Location
|
Ticks |
Pools
tested |
Number Pools Positive
|
|||
|
DFA
|
PCR**
|
Laboratory
|
|||||
| Borrelia spp. |
Borrelia spp. | Borrelia burgdorferi | |||||
| Alameda | Indian Joe Trail |
25
|
25
|
0
|
CDPH-VBDS | ||
| Little Yosemite Area |
4
|
4
|
0
|
CDPH-VBDS | |||
| Amador | Grinding Rock SP |
31
|
4
|
1
|
US Army | ||
| Calveras | Natural Bridge |
103
|
11
|
US Army | |||
| Water Treatment Site |
13
|
4
|
40
|
US Army | |||
| Contra Costa | Tilden Regional Park |
115 (170*)
|
115 (170*)
|
1 (4*)
|
CDPH-VBDS | ||
| Lake | Mendocino NF |
190 (2*)
|
19 (1*)
|
4
|
3
|
US Army | |
| Middletown |
5 (3*)
|
5 (3*)
|
0
|
CDPH-VBDS | |||
| Los Angeles | Angeles NF |
17
|
17
|
0
|
CDPH-VBDS | ||
| Charmlee Wilderness |
117
|
117
|
0
|
CDPH-VBDS | |||
| Malibu |
100
|
10
|
0
|
US Army | |||
| Madera | Chepo Saddle |
2 (1*)
|
1 (1*)
|
0
|
US Army | ||
| Marin | Point Reyes NS |
5
|
5
|
0
|
CDPH-VBDS | ||
| Marin Headlands |
67
|
67
|
3
|
CDPH-VBDS | |||
| Mariposa | Sierra NF |
20
|
2
|
0
|
US Army | ||
| Mendocino | Manchester SB |
26
|
26
|
0
|
CDPH-VBDS | ||
| Nevada | Nevada City |
17 (8*)
|
11 (2*)
|
0
|
US Army | ||
| Riverside | San Bernardino NF |
26 (1*)
|
26 (1*)
|
0
|
CDPH-VBDS | ||
| San Bernardino | San Bernardino NF |
6
|
2
|
0
|
US Army | ||
| San Diego | Cleveland NF |
24
|
3
|
0
|
US Army | ||
| Cleveland NF |
23
|
23
|
0
|
CDPH-VBDS | |||
| San Joaquin | Carnigie SP |
22
|
8
|
0
|
US Army | ||
| Santa Clara | Henry Coe SP |
100 (11*)
|
10 (1*)
|
2 (1*)
|
2 (1*)
|
US Army | |
| Shasta | Anderson River Park |
38
|
4
|
0
|
US Army | ||
| Baily Cove CG |
18
|
2
|
0
|
US Army | |||
| Anderson |
51
|
5
|
0
|
US Army | |||
| Redding |
70
|
7
|
0
|
US Army | |||
| Stanislaus | Patterson |
3
|
2
|
0
|
US Army | ||
| Total ticks tested |
1,238 (196*)
|
535 (179*)
|
|||||
| Total pools positive |
4 (4*)
|
11 (1*)
|
5 (1*)
|
||||
* Nymphs; ** PCR primer sets were specific for B. burgdorferi;
Tests: DFA, Direct Fluorescent Antibody; PCR, Polymerase Chain Reaction;
CG, Campground; NF, National Forest; NS, National Seashore; SB, State Beach; SP, State Park;
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 (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
A Dermacentor tick
The California Department of Public Health and the DEET Education
Program are excited to announce the launch of our Tick-bite Prevention
Video Public Service Announcement (PSA) Contest! The purpose of the
contest is to create short video public service announcements to help
people understand how to prevent tick-bites.
The contest is open to California residents only. There are two age and
award categories for the Video PSA:
1) 17 and younger
2) 18 and older
The first place winner in both categories will receive $350 and an award certificate.
The winning videos may be featured on broadcast TV and/or radio and on government
and partner websitesand will remain available on YouTube. The winners may be invited
to press events and/or asked to appear in futurecontest promotional videos. Other
awards certificates will be issued for winners receivingsecond or third place or honorable
mention.
Complete contest rules and entry forms can be found at:
http://www.deetonline.org/CDPHvideocontest/
<http://www.deetonline.org/CDPHvideocontest/> . Entries are being
accepted through April 1, 2011.
We would like to ask for your assistance is distributing the information throughout California.
Please forward this entire email and attachment to any and all individuals and organizations who
may be interested.We are especially interested in getting the information into the hands of some
our incredibly talented young adultsand school children California.
If you have questions, please contact:
Claudia J. Erickson, MS, CHES
Health Education & Communication Specialist
Veterinary Public Health Section
CA Department of Public Health
(916) 552-9762 claudia.erickson@cdph.ca.gov <mailto:claudia.erickson@cdph.ca.gov>
Tickborne relapsing fever (TBRF) is a bacterial disease transmitted to people by soft ticks in the genus Ornithodoros. 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