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Tick Collection and Testing

Photograph of a person in a uniform checking very closely a white cloth, ready to pick something off the cloth.
Vector Ecologist Arielle carefully collects ticks from the drag cloth.
Photograph of a person in a grassy spot with trees in the background. The person is dressed in a uniform and is bent over looking closely at a white cloth.
Vector Ecologist Arielle checks a drag cloth for ticks after dragging in a wooded area.
Photograph of a hand holding a clear vial containing many small ticks. The background is a grassy area with a blue sky.
Ticks collected along a trail in a local park.
Person in brown and grey uniform kneeling next to a white cloth on the ground while looking at the cloth
Vector Ecologist Theresa carefully checks a cloth for ticks.
Person in blue short sleeve shirt with braided hair as seen from the side while looking into a compound scope. There are many small tubes nearby, and the person is using a pair of tweezers to move something under the scope.
Vector Ecologist Tara identifies and sorts ticks in the laboratory.
Photograph of a person in a uniform checking very closely a white cloth, ready to pick something off the cloth.
Photograph of a person in a grassy spot with trees in the background. The person is dressed in a uniform and is bent over looking closely at a white cloth.
Photograph of a hand holding a clear vial containing many small ticks. The background is a grassy area with a blue sky.
Person in brown and grey uniform kneeling next to a white cloth on the ground while looking at the cloth
Person in blue short sleeve shirt with braided hair as seen from the side while looking into a compound scope. There are many small tubes nearby, and the person is using a pair of tweezers to move something under the scope.

Our laboratory does not test ticks that have bitten people, but we can help identify ticks you've found on you or your pet. Learn more HERE.

To understand tick-borne disease risk across the County, District staff collect ticks at local parks each year from December through June, as ticks collected during these months are most likely to bite humans. Staff use white cloths to drag along trail edges or through forest understories to collect questing ticks – ticks that are actively seeking hosts for blood meals. Ticks are picked off the cloths and returned to the laboratory where they are identified to species and tested for pathogens.

Real-time PCR is used to test western black-legged ticks (Ixodes pacificus) for three tick-borne pathogens found in California. Associated tick-borne diseases are Lyme disease (specifically the Borrelia burgdorferi sensu lato complex which includes B. burgdorferi sensu stricto, the agent of Lyme disease), hard-tick relapsing fever (caused by Borrelia miyamotoi), and human granulocytic anaplasmosis (HGA) (caused by Anaplasma phagocytophilum). All three diseases may be vectored by both nymphal and adult ticks.

Adult ticks are tested in groups, or “pools,” of a maximum of five individuals. The results are reported as a minimum infection prevalence, or MIP. This is the standard way of expressing the proportion of vectors tested that are infected with a particular pathogen and assumes that only one tick in a given pool is infected. As prevalence values are highly dependent on the number of ticks collected, we sample 150 or more adult ticks per park, which increases the chance that our sample will represent the true prevalence. Learn more about our findings HERE. 

 

Page last reviewed: March 6, 2024

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