Don’t Let Dermacentor Ticks Make You Sick

It’s summer and that means peak season for the dog tick and Pacific coast tick (collectively called Dermacentor ticks)! These large, brown-colored ticks are very prevalent this time of year along the edge of trails and in brushy areas with tall grass all throughout California. Unfed, they can be nearly three times as large as the black-legged ticks that are prevalent during the winter and spring and can engorge to the size of a grape if left attached to repletion. Dermacentor ticks are also much more tolerant of hot temperatures and low humidity than their winter-loving cousins which allows them to distribute broadly and survive in places that should be too isolated for them – such as the bushes found in driveway circles or in people’s gardens.

Image from

Dermacentor ticks do not carry Lyme disease and the diseases they can carry, such as tularemia and Rocky Mountain spotted fever, are rare in California. These ticks may, however, cause tick paralysis which is a condition where patients demonstrate weakness or a loss of control usually in lower extremities following a tick bite. The condition usually reverses completely within 24 hours once the tick is removed but can lead to full paralysis that can spread to the lungs and heart as long as the tick remains attached. This condition can affect pets as well.

If you plan to enjoy the sunny weather outdoors, make sure you avoid areas where ticks like to quest. Stay away from tall grass at the edge of trails and wear repellent containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone. Check yourself every evening for ticks and shower soon after returning home. Keep pets on a leash when you hike so they will not pick up ticks that they can then pass to you when you give them a cuddle. It’s important to remember that most flea treatments for pets do not work on ticks and so pets should be checked for ticks every evening after entering tick habitat.