Tick-Borne Diseases in Santa Cruz County 2005

Annual Report 2005, Santa Cruz County Mosquito and Vector Control District

The County had six reported cases of Lyme disease, and one reported case of relapsing fever in 2005 from tick bites. Lyme disease continues to be the most important vector-borne disease in the State, with 94 reported cases in 2005. As part of an effort to enhance services, MVC now accepts, identifies, and submits ticks for Lyme disease testing for persons who have been bitten. Prevention of bites and recognition of symptoms by the public and physicians are the most recommended methods of dealing with tick-borne disease. There is currently no efficient means to control ticks other than clearing brush.

Reported Cases of Tularemia in California 2004

Annual Report 2005, Alameda County Vector Control Services

Tularemia, a diseased caused by strains of Francisella tularensis, is not commonly transmitted by contacting rodents or tick bites. However, three human cases of tularemia were reported to CDHS in 2004; two of which were likely acquired through a tick bite: one from Alameda County and one from Contra Costa County. The adult American dog tick (Dermacentor variabilis) removed from the Alameda case was tested positive by culture and PCR for F. tularensis (type B) by Center for Disease Control and Prevention (CDC). Because of the human cases and also its importance as a bioterrorism agent, the CDHS requested blood samples from various animals for testing. Blood samples from twenty-three rodents from various locations in Alameda County were submitted for testing. None of these samples showed infection with F. tularensis. United State Department of Agriculture (USDA) – Animal and Plant Health Inspection Service (APHIS) submitted additional twenty-eight blood samples of feral cats, skunks, Norway rats, jackrabbits and red foxes. Of these, one striped skunk tested positive for the tularemia pathogen.

San Mateo County: Lyme Disease Surveillance

Entomology Report November/December 2005, San Mateo County Mosquito Abatement District

Surveillance for the western black-legged tick, Ixodes pacificus, has commenced for the 2005-2006 season. Adults of this species are abundant along recreational trails from November through May. Surveillance is being conducted with the assistance of a number of other agencies to determine the risk of Lyme disease exposure in San Mateo County. Ticks are collected on trails commonly used by the public. They are dissected and tested in the District laboratory to determine the prevalence of infection with the Lyme disease bacteria, Borrelia burgdorferi. Agencies participating in this project include: 3 divisions of the San Mateo County Department of Public Health (Environmental Health, Communicable Disease Control, and the Public Health Laboratory), County Parks, and State Parks. Staff from the San Francisco Department of Public Utilities (the Water Department) are also assisting in collecting on Crystal Springs Watershed.

So far this season, collections have been made at 6 parks. Tick density was low on the trails sampled early in the season (November). Surveillance in December yielded a larger number of ticks, with the highest density in Big Canyon Park. The first positive ticks of the season were collected from the San Andreas Trail. This site has yielded positive ticks in the past. Parks with low tick density will be sampled again later in the season. Other parks that may be surveyed this season, include Mills Canyon Park in Burlingame, Spur Trail Park in Millbrae, Edgewood Park in Redwood City, Smith Field Park in Half Moon Bay, and Sawyer Camp Trail in San Mateo.

Previous related entries:

San Mateo County: Lyme Disease Surveillance, October 2005
San Mateo County: Lyme Disease Surveillance, January 2005

Tick Infection Rates in Marin County 2005

Laboratory Report 2005, Marin / Sonoma Mosquito and Vector Control District

% infection of I. pacificus with B. burgdorferi
China Camp State Park, Marin County, 2005
Female ticks   4.9%
All ticks      3.5%

Tick Collection and Tick-borne Disease Surveillance (by Kristen Holt).
The western deer tick, Ixodes pacificus, is the most important carrier of Lyme disease and other tick-borne disease agents in northern California. During 2005, we collected a total of 577 deer ticks from China Camp State Park near San Rafael, to test for the Lyme disease agent. Twenty ticks (3.5%) were carrying the Borrelia bacterium. The rate was higher in female (4.9%) than male ticks.

Ticks and Lyme Disease in Contra Costa County 2005

2005 Annual Report, Contra Costa County Mosquito And Vector Control District

Tick Testing

Bollinger Canyon Rd, San Ramon Site
A total of 670 adult Western black-legged ticks were collected from the Bollinger Canyon Road site 1A this season. Seventy four ticks were tested (45 females, 29 males) for the presence of Lyme disease, using an Indirect Fluorescent Antibody test (IFA). Two of the seventy-four ticks tested were found to be positive for the Lyme disease, yielding a 2.7 percent infection rate. This is the twelfth season for which ticks have been tested from this site. The average infection rate over the twelve year period is 3.71 percent, which is slightly higher than the Californian State average of 2.0 percent. The chart below shows the Lyme disease (B. burgdoferi) infection rate at the Bollinger Canyon Site between the 1993-94 to 2004-05 seasons.

Springhill Rd, Lafayette Sites
In addition to our regular Lyme disease IFA testing, a total of 374 adult Western black-legged ticks were collected from five sites near Springhill Road, Lafayette, and were tested using real-time PCR by Dr. Alan Barbour of University of California, Irvine, for the presence of two species of Lyme disease causing bacterium, Borrelia burgdorferi and Borrelia miyamotoi. Borrelia miyamotoi is closely related to B. burgdoferi, but at this time has not been shown to cause disease in humans. This location was chosen as it was an area previously known to have had high Lyme disease infection rates in Western black-legged ticks that were collected by both Contra Costa Mosquito & Vector Control staff and those submitted by the public to our office for testing. The infection rates have varied yearly from 0-14 percent.

Alameda County Lyme Disease Surveillance, 2004-2005

Annual Report FY 2004-2005, Alameda County Vector Control Services

As part of the Lyme disease surveillance program, staff collect and identify ticks, and may recommend testing for tick borne disease when appropriate. Field surveys were conducted at seven locations, which resulted in the collection of 446 questing ticks of which 439 were Ixodes pacificus, the Lyme disease vector. None of these ticks were confirmed to be Lyme disease positive by direct immunofluorescence (IFA). Forty four residents or pets from Alameda County were bitten by ticks. These were submitted to the Sonoma County Public Health Laboratory for Lyme disease testing. One local ticks which bit Alameda County Residents tested positive for the Lyme disease spirochete. The District now has the capability of conducting Lyme disease IFA Tests. We hope to expand this capability when new staff are hired.