Table 3. Prevalence of Rickettsia philipii and Rickettsia rhipicephali detected in Dermacentor occidentalis, by county, California, 2009–2015.
| County | Stage | Total tested | R. philipii | R. rhipicephali |
|---|---|---|---|---|
| # positive (prevalence) | # positive (prevalence) | |||
| Alameda | Adult | 190 | 0 | 12 (6.3%) |
| Nymph | 33 | 0 | 0 | |
| Amador | Adult | 1 | 0 | 1 (100%) |
| Butte | Adult | 16 | 0 | 1 (6.3%) |
| Nymph | 1 | 0 | 0 | |
| Calaveras | Adult | 95 | 0 | 4 (4.2%) |
| Colusa | Adult | 2 | 0 | 0 |
| Contra Costa | Adult | 203 | 0 | 15 (7.4%) |
| Nymph | 17 | 0 | 1 (5.9%) | |
| Larvae | 7 (7 pools) | 0 | 0 | |
| El Dorado | Nymph | 31 | 0 | 6 (19.4%) |
| Fresno | Adult | 4 | 0 | 1 (25%) |
| Humboldt | Adult | 10 | 0 | 0 |
| Inyo | Adult | 12 | 0 | 1 (8.3%) |
| Kern | Adult | 24 | 0 | 0 |
| Lake | Adult | 645 | 15 (2.3%) | 59 (9.2%) |
| Nymph | 155 | 4 (2.6%) | 16 (10.3%) | |
| Larvae | 284 (47 pools) | 2 (0.7%) | 3 (1.1%) | |
| Lassen | Adult | 3 | 0 | 0 |
| Los Angeles | Adult | 1025 | 51 (5.0%) | 278 (27.1%) |
| Marin | Adult | 83 | 0 | 1 (1.2%) |
| Nymph | 10 | 0 | 0 | |
| Mendocino | Adult | 3 | 0 | 0 |
| Nymph | 89 | 1 (1.1%) | 18 (2.0%) | |
| Larvae | 3 (3 pools) | 0 | 0 | |
| Monterey | Adult | 173 | 0 | 22 (12.7%) |
| Larvae | 1 (1 pool) | 0 | 0 | |
| Napa | Adult | 10 | 0 | 1 (10%) |
| Nevada | Adult | 14 | 0 | 1 (7.1%) |
| Orange | Adult | 341 | 14 (4.2%) | 71 (20.8%) |
| Placer | Adult | 76 | 0 | 3 (3.9%) |
| Riverside | Adult | 46 | 1 (2.2%) | 2 (4.4%) |
| Sacramento | Adult | 6 | 0 | 0 |
| Nymph | 3 | 0 | 0 | |
| San Benito | Adult | 23 | 0 | 4 (17.4%) |
| San Bernardino | Adult | 296 | 1 (0.3%) | 20 (6.8%) |
| San Joaquin | Adult | 53 | 0 | 0 |
| San Luis Obispo | Adult | 31 | 0 | 3 (9.7%) |
| San Mateo | Adult | 386 | 3 (0.8%) | 4 (1.0%) |
| Nymph | 1 | 0 | 0 | |
| Santa Barbara | Adult | 60 | 6 (10.0%) | 6 (10.0%) |
| Santa Clara | Adult | 154 | 5 (3.3%) | 19 (12.3%) |
| Larvae | 1 (1 pool) | 0 | 0 | |
| Santa Cruz | Adult | 4 | 0 | 0 |
| Shasta | Adult | 83 | 0 | 2 (2.4%) |
| Nymph | 1 | 0 | 0 | |
| Siskiyou | Adult | 48 | 0 | 1 (2.1%) |
| Sonoma | Adult | 357 | 0 | 11 (3.1%) |
| Nymph | 221 | 0 | 29 (13.1%) | |
| Larvae | 178 (12 pools) | 0 | 4 (2.3%) | |
| Trinity | Adult | 2 | 0 | 1 (50.0%) |
| Tuolumne | Adult | 83 | 0 | 2 (2.4%) |
| Ventura | Adult | 2 | 0 | 0 |
| Yuba | Adult | 1 | 0 | 0 |
| Total | Adult | 4565 | 96 (2.1%) | 546 (12.0%) |
| Nymph | 562 | 5 (0.9%) | 70 (12.5%) | |
| Larvae | 474 (71 pools) | 2 (0.4%) | 7 (1.5%) |
*Minimum infection prevalence is reported in larvae.