Alameda County: Tularemia Surveillance 2006-2007

Annual Report 2006-2007, Alameda County Vector Control Services

Tularemia is caused by the bacterium Francisella tularensis that infects a variety of arthropods and vertebrates. Symptoms of human tularemia may include fever, chills, malaise, and fatigue. The disease is commonly transmitted by contacts with rabbits, insects, or tick bites. In Alameda County, a confirmed human case, transmitted by an American dog tick, Dermacentor variabilis was reported by CDHS in 2004. Since tularemia is classified as a bio-terrorism agent, the CDHS requested blood samples from various animals for testing. In 2006, 12 rodent samples were submitted; results are still pending.

Alameda County: Lyme Disease Surveillance 2006-2007

Annual Report 2006-2007, Alameda County Vector Control Services

As part of the Lyme disease surveillance program, our staff collects and identifies ticks, and recommends testing for tick borne disease when deemed appropriate. Our District provides consultations, educational resources, tick identification, and testing facilities for Lyme disease. Fifteen Ixodes pacificus ticks were submitted to the Sonoma County Public Health Laboratory for Lyme disease testing; all tested negative. The District now has the capability to perform Lyme disease indirect fluorescent antibody (IFA) tests. We hope to expand this capability when new staff is hired.

San Mateo County: Population Dynamics of the American Dog Tick and Pacific Coast Tick

Entomology Report June 2007, San Mateo County Mosquito Abatement District

District staff have been monitoring the seasonal population dynamics of the American Dog tick (Dermacentor variabilis) and the Pacific Coast tick (Dermacentor occidentalis) along the coast this year. These ticks are potential vectors of tularemia and Rocky Mountain Spotted Fever in California. Human cases of these diseases appear to have been acquired in San Mateo County during the past 3 years. Cases of tularemia have occurred in children camping south of Pescadero in 2004 and 2006. In 2004, a tick removed from a patient tested positive and in 2006, infection was detected in local ticks collected in the same area.

Adults of these ticks appear during spring and summer months. Because they are not vectors of Lyme disease, they have not been surveyed by District staff as extensively as the Western black-legged tick. The District is now sampling for these ticks on a weekly basis to further characterize their seasonal population trends. This information will be incorporated into public education campaigns that teach people to avoid tick-borne diseases.

Previous related entries:

San Mateo County: Tularemia Detected in Coastal Ticks, September 2006

San Mateo County: Physician Survey on Lyme Disease

Entomology Report June 2007, San Mateo County Mosquito Abatement District

In conjunction with the San Mateo County Public Health Department, laboratory staff have surveyed over 100 physicians throughout the county to assess physician beliefs and awareness about Lyme Disease. So far, 9% of the surveys have been completed and returned. This survey will be used to develop educational materials, geared towards physicians, informing them of the risk of acquiring Lyme Disease in the county.

Previous related entries:

Survey of San Mateo County Physicians on Lyme Disease, March 2007
San Mateo County Physician Survey on Lyme Disease, November/December 2006

San Mateo County: Nymphal Tick Surveillance

Entomology Report May 2007, San Mateo County Mosquito Abatement District

Testing nymphs, the juvenile stage, is an integral part of the Lyme disease surveillance program. Their extremely small, hard to see, size of this stage contributes to their role in transmission of Lyme disease. Nymphs are collected by dragging white flannel sheets over forest floors with dense leaf litter, the preferred habitat of nymphal ticks. Lab and field staff regularly monitor, collect, and test ticks in these areas to determine prevalence of Lyme disease in nymphal ticks. So far, surveys for nymphs have been carried out in Los Trancos Woods, Costanoa Resort in Pescadero, Skyline Ridge Open Space, Edgewood Park in Redwood City and Laurelwood Park in San Mateo.

Previous related entries:

San Mateo County: Tick Flagging with Santa Clara County Vector Control District, April 2007

Orange County: Rocky Mountain Spotted Fever Confirmed in County Park

Rocky Mountain Spotted Fever confirmed in County park, Orange County Vector Control District

Rocky Mountain Spotted Fever confirmed in County park. A Pacific Coast Tick, Dermacentor occidentalis that was collected in Aliso and Wood Canyons Wilderness Park tested positive for Rocky Mountain Spotted Fever (RMSF). Orange County Vector Control District (OCVCD) collected the tick on January 29, 2007 as part of an ongoing surveillance program. Samples were submitted to the California Department of Health Services (DHS), although the actual testing was done by The Centers for Disease Control and Prevention (CDC). The District received confirmation on the positive tick from DHS on, March 30, 2007.

Los Angeles County West: Locations of Lyme Positive Ticks

Locations of Lyme Positive Ticks, Los Angeles County West Vector Control District

Map:
Sites where ticks positive for Lyme disease bacterium have been found in the district

Charmlee Park
Malibu Creek State Park
Tapia State Park
Topanga State Park
Will Rogers State Park
Palos Verdes Estates - Bluff Cove
Rolling Hills - Purple Canyon Trail

Lyme Disease in Santa Clara County: Tick Infection Rates

Source: Lyme Disease in Santa Clara County, Santa Clara County Vector Control District

Location of tick sampling    % positive to Borrelia burgdorferi
Freemont Older                     3.85
Foothills Open Space Dist.         2.86
Sierra Azul                        2.86
Sanborn Skyline                    2.78
Alum Rock Park                     2.75
Uvas County Park                   2.39
Duveneck Windmill OSD              2.27
Villa Montalvo                     2.22
Almaden Quicksilver                1.72
Los Trancos                        1.26

San Mateo County: Tick Flagging with Santa Clara County Vector Control District

Entomology Report April 2007, San Mateo County Mosquito Abatement District

In April, District staff focused on collection of nymphal ticks for Lyme disease testing. On April 18, District laboratory staff collaborated with Santa Clara County Vector Control to search for nymphal ticks in sites near the county border. Sampling was carried out on Old Spanish Trail in Los Trancos Woods and at Foothill Park in Los Altos. These ticks are in the process of being tested for Lyme disease. Ixodes pacificus nymphs are active during the spring and early summer and are easily overlooked due to their small size. Nymphs infected with the bacteria that causes Lyme disease have been found throughout San Mateo County.

San Mateo County: Public Education and Other Activities: Lyme Disease and Ticks

Entomology Report March 2007, San Mateo County Mosquito Abatement District

• Dr. Chindi Peavey, the District Vector Ecologist, gave a presentation on Lyme Disease Ecology and Surveillance at El Camino Hospital on March 17 in conjunction with Dr. Anne Kjemtrup, from the California Department of Health Services, and Victor Romano, from Santa Clara County Vector Control.
• Laboratory staff distributed a press release on the presence of vector ticks in vacant lots in a well-developed residential area in Pacifica. This story was picked up and published in an article by the Pacifica Tribune. The article has generated a number of calls from residents on the coast. Laboratory staff visited additional sites and spoke with residents about ways to reduce the risk of acquiring Lyme Disease.
• Legislation declaring May as Lyme Disease Awareness Month is currently going through the state legislature.

Survey of San Mateo County Physicians on Lyme Disease

Entomology Report March 2007, San Mateo County Mosquito Abatement District

A pilot survey was performed to determine attitudes and beliefs of physicians in San Mateo County on the acquisition of Lyme Disease in the county, treatment options, and the possibilities of co-infections. Training was provided by the San Mateo County Public Health Department on survey completion and the pilot was performed with local infectious disease doctors. The questionnaire is now in the process of redesign to accommodate the needs of doctors for the full survey.

Previous related entries:

San Mateo County Physician Survey on Lyme Disease, November/December 2006

A 6-Year Analysis of Tick Surveillance in San Mateo County

Entomology Report February 2007, San Mateo County Mosquito Abatement District

% Infection of I. pacificus in San Mateo County Parks
Location             # Ix. pacificus Tested  % Infection
Pulgas Ridge                    60                3.3
Los Trancos Woods              733                2.5
Huddart Park                   140                2.1
Big Canyon Park                507                1.8
Crystal Springs Trail          556                1.6
San Pedro Valley Park          333                0.9
Laurelwood Park                428                0.7
Edgewood Park                  195                0.5

An analysis of tick surveillance data from 2002 through February 2007 in San Mateo County was performed. Adult Ixodes pacificus ticks have been collected from 11 parks. Thus far Lyme disease spirochetes have been detected in ticks from 8 parks (Big Canyon Park, Crystal Springs Trail, Edgewood Park, Huddart Park, Laurelwood Park, Los Trancos Woods, Pulgas Ridge, and San Pedro Valley Park). The prevalence of infection in ticks at these parks ranged from 0.5% - 3.3%. Ticks collected from Costanoa, Sweeney Ridge, and Water Dog Lake have not yet tested positive for Lyme Disease spirochetes.

Previous related entries:

Tick Surveillance in San Mateo County, January 2007, January 2007
Tick Surveillance in San Mateo County, December 2006, December 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, June 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, April 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, March 2006
San Mateo County: Lyme Disease Surveillance 2006, February 2006
San Mateo County: Lyme Disease Surveillance 2006, January 2006
San Mateo County: Lyme Disease Surveillance, November/December 2005
San Mateo County: Lyme Disease Surveillance, October 2005
San Mateo County: Lyme Disease Surveillance, January 2005

Tick Surveillance in San Mateo County, January 2007

Entomology Report January 2007, San Mateo County Mosquito Abatement District

In January, tick collections were made from Edgewood Park, (Redwood City), Huddart Park, (Woodside), Laurelwood Park (San Mateo), Water Dog Lake (Belmont), and Costanoa (Pescadero). So far, a total of 827 ticks from 5 parks were collected. Evidence of infection with Lyme disease spirochetes was detected for the first time in Edgewood Park (1 positive) and Laurelwood Park (3 positives).

The District was contacted from residents of Belmont (near Water Dog Lake) and Pacifica with concerns about ticks in their neighborhoods. In Pacifica, questing ticks can be found in the open spaces between homes. In Belmont, western black-legged ticks were found inside a home adjoining the open space around Water Dog Lake, presumably brought in by the family cat. These instances illustrate the need to watch out for ticks even if one does not engage in outdoor activities at this time of year.

Previous related entries:

Tick Surveillance in San Mateo County, December 2006, December 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, June 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, April 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, March 2006
San Mateo County: Lyme Disease Surveillance 2006, February 2006
San Mateo County: Lyme Disease Surveillance 2006, January 2006
San Mateo County: Lyme Disease Surveillance, November/December 2005
San Mateo County: Lyme Disease Surveillance, October 2005
San Mateo County: Lyme Disease Surveillance, January 2005

San Mateo County: Results of the Efficacy of Suspend on Density of Ticks Along a Recreational Trail

Entomology Report January 2007, San Mateo County Mosquito Abatement District

The insecticide Suspend (Deltamethrin) was evaluated for its ability to control Dermacentor ticks along a recreational trail in San Mateo County. Three days post treatment, showed a 98% decline in ticks. One week post treatment resulted in 100% control and after seven weeks the trail was still at a density of 0 ticks. This study showed that the material is very effective in controlling Dermacentors. In the future, another study will be performed to evaluate the efficacy of Suspend on Ixodes pacificus ticks.

Previous related entries:

San Mateo County: Trial Application of Suspend for Control of Ticks, May 2006
San Mateo County: Trial Application of Suspend for Control of Ticks, April 2006

San Mateo County: Results of the Evaluation of Trailside Mowing as a Tick Control Method, January 2007
San Mateo County: Effects of Mowing on Summer Tick Populations, June 2006

San Mateo County: Results of the Evaluation of Trailside Mowing as a Tick Control Method

Entomology Report January 2007, San Mateo County Mosquito Abatement District

This four-week study concluded that the mowing of grass on the sides of public recreation trails in San Mateo County was not an effective control method for Dermacentor ticks. In fact, although the sample size was relatively small, the density of Dermacentor variabilis ticks was found to have increased slightly on sites after they had been mowed. The density of Dermacentor occidentalis was not shown to have any significant relationship to mowing. While they do not transmit Lyme Disease, Dermacentor ticks remain a public health concern, as they are known to vector both Rocky Mountain Spotted Fever and Tularemia, and are very common ticks in San Mateo County.

Previous related entries:

San Mateo County: Effects of Mowing on Summer Tick Populations, June 2006

San Mateo County: Results of the Efficacy of Suspend on Density of Ticks Along a Recreational Trail, January 2007
San Mateo County: Trial Application of Suspend for Control of Ticks, May 2006
San Mateo County: Trial Application of Suspend for Control of Ticks, April 2006

Ticks and Lyme Disease in Contra Costa County 2006

2006 Annual Report, Contra Costa County Mosquito and Vector Control District

Lyme disease is a bacterial infection transmitted by the Western black-legged tick (Ixodes pacificus), also known as the deer tick. While Lyme disease is rare in Contra Costa County (on average there are two to four human cases reported per year), it can cause serious complications if not treated promptly. The District monitors the risk of Lyme disease by collecting and testing black-legged ticks from several locations that we have been monitoring for as long as 12 years. These include Bollinger Canyon Rd., San Ramon; Springhill Rd., Lafayette; and the Bear Creek area of Briones Regional Park. The adult Western black-legged tick population was below average for most of the season, except during the last half of March where counts slightly exceeded the average. An unusually high number of days with rainfall during the collecting season limited the number of possible collection days; thus reducing the numbers of ticks collected. The graph below shows the average number of ticks that were collected from these locations.

On average, only one or two in a hundred black-legged ticks test positive for Lyme disease, although we have found a few locations where the rate is higher, and these tend to change over time. In 2006, we collected and tested 132 ticks from three locations; the highest infection rate was in the Bollinger Canyon area in San Ramon where three out of 58 ticks tested positive (just over 5 percent).

We also identify and test ticks brought in by members of the public who have been bitten. If the ticks are reasonably intact and not dried out, we can test them in our own laboratory free of charge. If they are in poor condition or dead, a more sensitive test is required and county residents have the option of allowing us to send the tick to a private laboratory for a fee of $60 (our cost). Out of 54 ticks tested for residents in 2006, only one was positive for Lyme bacteria (just below 2 percent).

Tick Surveillance in San Mateo County, December 2006

Entomology Report November/December 2006, San Mateo County Mosquito Abatement District

The Western black-legged tick, the vector of Lyme disease, becomes active with the commencement of winter rains. These ticks require cool, moist conditions to survive and are commonly encountered along recreational trails during winter. Last year, 22 trails in 8 parks were surveyed by District staff and other agencies. This year, the District will again coordinate with the San Mateo County Department of Public Health and the Land and Resources Division of the San Francisco Public Utilities Commission in surveying additional parks within the county. So far this season, 669 ticks have been collected and are in the process of being tested for Lyme disease.

Park             Total # Females  Total # Males  Adult Density
                 Collected        Collected      ticks/100 ft
Edgewood Park                 51             70            0.9
Huddart Park                   8              9            0.2
Laurelwood Park              130            129           12.5
Water Dog Lake                50             97            2.0
Costanoa                      62             63            5.2
Grand Total (12/8/06-1/3/07) 301            368

Previous related entries:

San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, June 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, April 2006
San Mateo County: Lyme Disease Surveillance Winter/Spring 2005-06, March 2006
San Mateo County: Lyme Disease Surveillance 2006, February 2006
San Mateo County: Lyme Disease Surveillance 2006, January 2006
San Mateo County: Lyme Disease Surveillance, November/December 2005
San Mateo County: Lyme Disease Surveillance, October 2005
San Mateo County: Lyme Disease Surveillance, January 2005

San Mateo County: Physician Survey on Lyme Disease

Entomology Report November/December 2006, San Mateo County Mosquito Abatement District

The District is working with epidemiologists from the Health Department of San Mateo County this winter to determine the level of awareness among local physicians about Lyme Disease. A survey will be administered to local infectious disease physicians. The survey will be based on one developed by California Dept. of Health Services in 2004. The former survey was administered statewide, but the response rate in many counties was very low (only 2 physicians replied in San Mateo County). By conducting the survey at a local level and contacting physicians by telephone, it is hoped that we can increase the response rate. This information will help to assess the level of awareness among local doctors about the existence of Lyme disease among ticks here in San Mateo County.