In response to parental concerns about the possibility of children picking up ticks on athletic fields, the District recently conducted tick surveys at seven elementary and middle schools in the Pacifica School District (PSD). Many schools in Pacifica border open spaces that host wildlife and large areas of tick habitat, and are near parks and other outdoor recreation areas where tick exposures are common. All athletic fields and grassy areas were sampled at each school, as well as any bordering natural habitat that could present a hospitable environment for ticks.
Three species of ticks were collected, two of which (Dermacentor ticks) are known to regularly bite humans. No more than five Dermacentor ticks were found at any one school. The local tick species implicated in the transmission of Lyme disease, Ixodes pacificus, is not typically found in late summer, and was not collected in any of these surveys.
Common Tick Species Encountered in Pacifica
|Tick Species||Common Name||Lyme disease vector?||Found in August survey?|
|Dermacentor occidentalis||Pacific coast tick||No||Yes|
|Dermacentor variabilis||American dog tick||No||Yes|
|Haemaphysalis laporispalustris||Rabbit tick||No||Yes|
|Ixodes pacificus||Western black-legged tick||Yes||No|
Most of the ticks collected in these surveys were found in natural areas with brushy vegetation, tall grass and weeds that bordered the schools. No ticks were found on athletic fields or in the walkways between buildings. Well-mowed athletic fields and other landscaped areas typically present poor environments for ticks, as they do not maintain the environmental conditions required for tick survival. District staff met with administrators from the PSD, staff at individual schools, and concerned parents to share results of the surveys and discuss best practices to minimize the risk of tick bites for students.
It is important to note that late summer is not known to be a season when human-biting ticks are particularly abundant in this part of California. Human biting ticks, including Ixodes pacificus, the vector for Lyme disease, are most commonly encountered from winter through early summer. Nevertheless, as our recent surveys have demonstrated, it is possible to find ticks at low levels at any time of year in the appropriate habitat. The District will continue to work with schools in areas where ticks are common to foster tick safety awareness and conduct additional surveys during the peak tick season.