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Ticks & Lyme disease


Ticks
Contra Costa Mosquito and Vector Control District conducts annual surveillance for the Western Black-Legged Tick and the bacteria that cause Lyme disease. The tick is most common in the hills of the San Ramon and Diablo Ridges. County wide, an average of only one to two percent of these ticks are actually infected.




Tick identification/Lyme disease testing
Contra Costa Mosquito and Vector Control District provides a free tick identification service (for residents of Contra Costa County only). Identification is important since only one of the three tick species that commonly bite humans and pets in this area (the Western Black-Legged Tick) is known to transmit the bacteria that cause Lyme disease. If you are bitten by a tick, save it in a vial or ziploc bag with a small piece of slightly moist cotton or paper towel and bring or mail it to our office (map). Our laboratory will identify it free of charge. If the tick is brought in alive, we may be able to test it for Lyme bacteria (depending on staff availability) at no cost to you. If it is dead we can arrange to have it tested by a diagnostic laboratory for a fee of $60, payable by check or credit card. We cannot diagnose Lyme disease or recommend treatment: please contact your physician.



Microscopic view of Borrelia burgdorferi, the spirochete (spiral bacteria) that causes Lyme disease

What is Lyme disease?
Lyme disease (Lyme Borreliosis) is a preventable bacterial disease transmitted to humans and animals by the bite of a Western Black-Legged tick. It may be cured by early diagnosis and appropriate antibiotic treatment, but it may persist in the human body for years if not properly treated. The natural history of this disease is not completely understood, and the illness it produces in humans can be difficult to diagnose because of the varied symptoms.  Lyme disease was named for Old Lyme, Connecticut, where the first cases were reported. The first case in California was reported in 1978. It is the most commonly reported tick-borne disease in California, as well as the rest of the United States.


If I am bitten by a tick will I get Lyme disease?
Only about 1-2% of the adult Western Black-Legged ticks in Contra Costa County are infected with the bacterium that causes Lyme disease. In some areas north of the San Francisco Bay Area, up to 5% of the adults may be infected; this is still much lower than the northeastern U.S. where 30-60% or more of the adult ticks may be infected. Even an infected tick will not necessarily transmit Lyme disease; evidence indicates that the bacterium is usually not transmitted to humans until the tick has fed for at least 24 hours.




What should I do if I am bitten by a tick?
Since it may take a day or more for the tick to transmit the bacteria, prompt removal of ticks should prevent disease transmission. 

Grasp the tick with a tissue or tweezers, (Never with your bare hands!) as close to your skin as possible. If ticks are crushed with bare fingers, exposure to the tick body fluids may lead to transmission of the disease organisms. 

GENTLY pull the tick from the skin. Do not twist or "unscrew"; the tick. Do not attempt to remove by burning with matches or by applying vaseline, kerosene etc. since this can cause the tick to regurgitate its gut contents, increasing the risk of disease transmission. 

Apply an antiseptic to the bite area after removing the tick. Wash your hands with soap and water. 

Save the tick for identification! If you are a Contra Costa County resident you can bring or mail it to our office at 155 Mason Circle in Concord (map). Otherwise contact your local Vector Control or Mosquito Abatement District, or state or county Health Department to determine if the tick is one capable of transmitting Lyme disease. 

If the tick cannot be removed or part of it is left in the skin, consult your physician.


What should I do if I think I have Lyme disease?
Early recognition is very important. If you have found a tick attached to your skin, or you were in an area where ticks are known to occur, and you have any of the symptoms listed below, tell your physician immediately of your suspicions and save the tick. This information should help your physician make a diagnosis. This may be especially important for pregnant women. If you have developed a rash as described below, take a picture of it for future reference.


What are the signs and symptoms of Lyme disease? 

Acute Stage

The first recognizable sign usually is a slowly enlarging red rash, known as erythema migrans (EM), about the size of a half dollar or larger. This is noticed in 60-80% of persons who contract Lyme disease. One or more rashes may appear on the body. The rash occurs 3-30 days (average 7-9 days) after the bite of an infected tick. The rash expands over a period of days or weeks to form a large circular lesion, often with a central clearing ("bull's eye").

Flu-like symptoms may also occur in this stage. These symptoms may persist, change, disappear and reappear intermittently for several weeks.

Often a tick bite will be followed by a reaction within hours creating a redness at the site of the bite which does not expand and disappears within a couple of days, but this must not be confused with Lyme disease.

Chronic Stage
Initially during this stage, patients may experience migratory pain in joints, tendons, muscles, and bones often without joint swelling or redness; however, months after onset, arthritis with marked joint swelling is common. Some infected persons may develop long-term complications weeks to months after the initial symptoms. These complications may include disorders of the heart or nervous system. Abnormalities of the heart include various degrees of heart block (disturbance of the electrical conduction system). Facial paralysis (Bell's palsy) and other nervous system abnormalities may occur.

Months to years after disease onset, patients may develop joint pain and swelling that appears and disappears intermittently for several years. Large joints, especially the knees, are most affected. Lyme arthritis may become chronic, with erosion of cartilage and bone. Chronic neurologic symptoms and chronic skin conditions may also occur.


Is Lyme disease treatable?
Yes! Most case of Lyme disease can be successfully treated with antibiotics, but early treatment is important.


Are blood tests accurate in diagnosing Lyme disease?
Blood tests have been used in addition to evaluating clinical symptoms for diagnosis, but the test alone is not sufficient for diagnosis. At this time the Centers for Disease Control are working to standardize the blood tests to ensure accurate test procedures and interpretation of the results.

The blood test should not be obtained until several weeks after the tick bite because the blood test is not very sensitive in the early phase of the disease. The test measures antibody level against the bacteria in the blood. Antibody levels can be affected by medications and infection by other disease organisms which may cause the test results to be inaccurate.


How can I protect myself from tick bites?

• Wear long pants and long-sleeved clothing and shoes covering the toes when in "tick-country". Don't wear shorts, sandals, or sleeveless shirts!

• Wear light colored clothing so ticks can be easily seen and removed before they become attached to the skin.

• Tuck pants into socks or boots, and shirt into pants.

• Use insect repellent on shoes, socks, pants, and shirt. Restrict the use of insect repellents to only exposed skin or clothing following label instructions. do not apply repellents to face. contrary to some advertisements there is no"special" formula for ticks; most insect repellents contain the same active ingredients-DEET (N,N-diethyl-meta-toluamide) or permethrin.

• Choose wide trails and walk in the center of the trail. Avoid brushy and grassy areas and off-the-trail hikes.

• Thoroughly check yourself and your children frequently for ticks. You and your family can continue to safely enjoy our great parks and open space areas by following the above guidelines for personal protection.

Adult female Western black-legged tick (left) versus American dog tick (right) 

Of the three species of ticks that commonly bite people in our area, only the Western Black-Legged tick (Ixodes pacificus) is considered a carrier of Lyme disease. This tick is closely related to the Deer Tick (Ixodes scapularis) which is found in the Eastern U.S. The adult female is reddish-brown with black legs, about 1/8 of an inch long; males are smaller and entirely brownish-black. Ticks that have taken a blood meal (called engorged) will appear much larger, gray in color, and can reach the size of a pea. Ticks in their immature life stages can be as small as the head of a pin or poppy seed.

Tick life stages (from left): larva, nymph, adult male, adult female

Where is the Western Black-Legged Tick found?

This tick can be found on grasses and brush in rural settings which receive afternoon shade. These ticks do not like sunny, open areas. The ticks feed on deer, rabbits, lizards, mice, and other animals. Ticks do not fly, jump, or drop from trees. Ticks climb on the tips of vegetation, typically along animal trails or paths, and wait for an animal or human host to brush against them so they can attach themselves. This behavior is called "questing".

Is Lyme disease only a summertime threat?
NO! It can be contracted during any season of the year. Ticks feed at various times of the year, including winter. The adult ticks are usually seen November through April. The nymphal tick (an immature stage) is usually present early spring to late summer, peaking in mid to late May. Due to the smaller size of the nymph and more outdoor activity by people, chances of an infectious tick bite are increased.


Is there a vaccine available against Lyme disease?
A Lyme disease vaccine was approved for human use in 1998 but is no longer available.  The Centers for Disease Control and the California Department of Health Services consider Contra Costa County a low risk area for Lyme infection and recommended that only persons with frequent exposure to ticks (park workers, landscapers etc.) consider vaccination. Contact your physician for more information.


Can pets get Lyme disease?
Yes! Lyme disease has been reported in dogs, (rarely in cats), horses, as well as a number of wild animals. Symptoms may include fever, loss of appetite, arthritis, intermittent paralysis, and lack of energy (no rash). The products used for fleas will also control ticks. Check for ticks and brush after exposure to ticks. Have your pet examined by a veterinarian if you suspect it has Lyme disease.