Foley Laboratory in Infectious Disease Ecology

Humboldt Tick-Borne Disease Study

Goals of our Study: We are embarking on a large One Health study assessing human, domestic animal, and wildlife risks of tick-borne disease, how to prevent problems across the entire family, and how to manage disease once it arrives. We have chosen Humboldt County as the main site for this prospective study because of the high local risk of disease in multiple species including humans, dogs, and horses. Most tick-borne disease is preventable and treatable if caught early! Please use these informational resources and links to learn to protect yourself and your pets.


Northern California  is home to over 5 species of human biting ticks that can transmit disease. Northern California counties have the highest rate of tick-transmitted diseases in the state.

Western Blacklegged Tick (Ixodes pacificus): Can transmit anaplasmosis and Lyme disease. Most common tick found on people in California.
ixodes pacificus

American Dog Tick and Pacific Coast Tick (Dermacentor sp): Can transmit spotted fever group rickettsias, including Rocky Mountain spotted fever.

american dog tick

Brown Dog Tick (Rhipicephalus  sanguineus): Can transmit Rocky Mountain spotted fever. Common in California  on dogs but rarely feeds on people.

brown dog tick

Tick-Transmitted Diseases

Lyme Disease is the most common tick transmitted disease in North America and is caused by the bacteria Borrelia burgdorferi. Every case is very different but people may develop any of the following symptoms which generally occur 3-30 days after the tick bite: tiredness, chills, fever, headache, muscle and joint aches, swollen lymph nodes or a red expanding rash. 


 If you have had a recent tick bite and are experiencing any of these symptoms you should seek medical treatment.  Treatment for Lyme disease generally consists of a course of antibiotics.  If Lyme disease goes untreated, symptoms can become more serious and more difficult to treat.

Spotted fever group rickettsias are a group of bacteria that can cause illness in people such as Rocky Mountain spotted fever.  Symptoms of disease generally include fever, muscle aches, and a rash.  The appearance of the rash can vary depending on the specific type of bacteria.


Anaplasmosis (previously known as Human Granulocytic Ehrlichiosis) is caused by the bacteria Anaplasma phagocytophilum.  Symptoms of disease include fever, headache, chills and muscle aches.  In people with weakened immune systems, the illness may become more severe or even fatal.  Anaplasmosis is found all over the northern hemisphere and has been increasing in incidence in the United States, but is still considered rare is California.

Tick Prevention

The best way to prevent tick-transmitted diseases is to avoid tick bites.  The best ways to avoid ticks are to:

  • Use insect-repellents such as DEET and permethrin
  • Wear light colored clothing when outdoors so ticks are visible
  • Perform a thorough tick-check on yourself after being outdoors
  • Bathe or shower immediately after being outdoors to remove ticks that may be crawling around

It is also important to prevent ticks on your pets.  The best way to accomplish this is to use a flea and tick repellent such as Frontline Plus for dogs and cats or K9 Advantix  for dogs only.  Also check your pets for tick often, especially after they have been outdoors.

Tick Removal

If you find a tick on you or your pet, it should be removed as soon as possible.  A pair of fine-tipped tweezers or commercial tick removal device should be used to remove the tick.  Use the fine-tipped tweezers to grasp the tick as close to the skin as possible and gently pull upward with steady pressure.  DO NOT twist or jerk, as this could cause the mouth-parts to break off.  After removing the tick, clean the skin with soap and water or alcohol.  DO NOT use home remedies such as Vaseline, nail polish or burning with a match.

Tick offApply directly to the forehead.

If You Are Bitten

  • Remove the tick as soon as possible.  The sooner a tick is removed the less likely it is to transmit disease
  • If you develop a spreading rash or flu-like symptoms (fever, headache, chills, muscle ache) within 30 days after a tick bite, consult your physician.


For additional information on tick-transmitted diseases please visit:

  • Centers for Disease Control and Prevention 
  • California Department of Public Health