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Tick Surveillance, 2016-2017 Water Year

From January to April of 2017, laboratory staff from the San Mateo County Mosquito and Vector Control District collected ticks from 15 different parks and open spaces around the county.  Ticks were tested for three different disease-causing bacteria using the districts quantitative PCR machine.  Results displayed on the graph are Minimum Infection Rates (MIR).   MIR is an estimated percentage of infected ticks that used when ticks are pooled together before testing to save time and cost.  The following pathogens were tested for in the 2017 tick-born disease surveillance program: Borrelia burgdorferi sensu stricto, Borrelia miyamotoi, and Anaplasma phagocytophilum.

Borrelia burgdorferi sensu stricto (B.b.s.s) is the causative agent for Lyme disease in the United States.  Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart, and the nervous system.  In previous years, the lab tested for a less specific bacterial group that included other non-disease causing relatives of the bacteria.  Because a more specific test was used this year, the number may appear diminished.

Borrelia miyamotoi (B.m.) is the causative agent of relapsing fever.  This disease is not yet well characterized but it is believed to cause many similar early symptoms to Lyme disease that may resurface multiple times over the course of a few weeks.  At this time, there is no known long-term symptoms that arise if left untreated.

Anaplasma phagocytophilum (A.p) is the causative agent of human granulocytic anaplasmosis (HGA).  Symptoms of HGA also include fever, headache, chills, and muscle aches.  This is the first year the SMCMVCD lab has tested all collected ticks for A.p.

All of the preceding bacteria and transmitted specifically by the Western Black-Legged Tick (Ixodes pacificus).  The diseases they cause are treatable with antibiotics.

Park/LocationNearest City# Collected# Positive Pools for BbMIP for Bb# Positive Pools for BmMIP for Bm# Positive Pools for ApMIP for Ap
Big Canyon ParkSan Carlos201    
Crystal Springs Regional TrailMillbrae174      
Eaton ParkSan Carlos182      
Edgewood ParkRedwood City160      
Huddart ParkWoodside220      
Laurelwood ParkSan Mateo249      
Los Trancos Open Space PreservePortola Valley175      
Montara MountainMontara59
Portola Valley RanchPortola Valley279      
Pulgas Ridge Open Space PreserveRedwood City255      
Purisima Creek Open Space PreserveHalf Moon Bay35      
Quarry ParkEl Granada1      
Russian Ridge Open Space PreserveRedwood City273 
Thornewood Open Space PreserveWoodside599      
Water Dog Lake ParkBelmont189
County-wide Total 3051



February 2017 Update

The District laboratory is taking advantage of breaks in rainy weather to collect ticks from parks and open space areas in San Mateo County.   Ticks are collected by dragging a tick flag – a large white piece of flannel attached to a wooden rod – over the vegetation alongside trails.  The main target species of tick is Ixodes pacificus, the western black-legged tick, which vectors Lyme disease, Borrelia miyamotoi infection, and anaplasmosis.  The ticks collected will be tested for the presence of bacteria that cause these diseases.  The Ixodes pacificus ticks are in the adult stage of their life cycle in winter.

The District plans tick collection at 15 parks this season.  The parks were chosen because of popularity, high tick densities, historically high tick prevalence, or human tick-borne disease cases.   Thus far, ticks have already been collected at Water Dog Lake Park, Crystal Springs Regional Trail (San Andreas segment), Huddart County Park, Thornewood open space preserve, and Laurelwood Park.  These collections have revealed high abundances of ticks this year.  Residents should take care while in tick habitats to stay in the middle of trails, tuck socks into their pants, use tick repellent and check themselves thoroughly for ticks afterwards.

Tick Collection parks for 2017 Winter Season

Park/LocationNearest City/Town
Water Dog Lake ParkBelmont
Eaton ParkSan Carlos
Big Canyon ParkSan Carlos
Thornewood Open Space PreserveWoodside
Los Trancos WoodsPortola Valley
Quarry ParkHalf Moon Bay
Purisima Creek Redwood Open Space PreserveWoodside
Montara MountainPacifica
Russian Ridge Open Space PreservePortola Valley
Los Trancos Open Space PreservePortola Valley
Huddart County ParkWoodside
Pulgas Ridge Open Space PreserveRedwood City
Edgewood County ParkRedwood City
Crystal Springs Regional Trail - San Andreas SegmentMillbrae
Laurelwood ParkSan Mateo

Additional parks may be added, depending on weather.

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