Tick Talk

Once again she started climbing up the deeply furrowed trunk of the blue oak tree. This would be her second try to find an animal to land on and feast upon. Four hours and forty-two minutes later she reached the end of a branch 32 feet above the trail. She jockeyed around on the branch until she was directly above the trail. With tiny eyes, she patiently watched the terrain below. A mouse scurried across the trail and later a jackrabbit ran by, but they were too fast, too small, and mostly too far away to be likely victims. Finally, two days later, a young male deer wandered slowly along the trail, sniffing around for leafy morsels to munch on. The famished tick poised herself in readiness. When the timing seemed perfect, she leaped into the air and fell towards her unsuspecting prey. Her target was the deer's neck, but at the last crucial moment the deer turned his head to see what a noisy scrub jay was complaining about, and the tick missed by a mere quarter inch. She landed with a thud on the hard dirt of the trail. "Darn!" she muttered. But no one heard. To add insult to injury or, I guess, injury to injury, the young buck stepped squarely on top of her as he continued down the trail, looking for more greenery. Her tough little body protected her somewhat, and, pulling herself together, she began crawling (with a bit of a limp) back towards the trunk of the blue oak tree .   .   .   .

There is much myth and misinformation about ticks.  One commonly accepted belief is that ticks climb trees and wait to leap off and land on unsuspecting victims who wander by down below.  Although ticks may seem to have dropped from out of nowhere and lodged in your hairline, it's more likely that they posed on a grass stem, hitched a ride on your pants, and diligently climbed up you and your clothing until they found a spot they liked.

It may be that some ticks climb trees and launch themselves into the air.  But those that do, in my opinion, must be young thrill-seekers, mentally deranged, or suicidal.

Ticks at Coe Park

In Coe Park, we find ticks from late fall through late spring, the moister months of the year.  The park has three species of ticks that bite humans, two common species of hard-bodied ticks and one less common soft-bodied tick species.

The western black-legged tick is often seen early in the tick season.  The males have blackish-brown bodies, and the larger females have reddish-brown bodies.  They're fairly small ticks and, as you might expect, they both have black legs.

The Pacific Coast tick is also common in the park.  It looks a lot like the American dog tick (also called the wood tick), which might also inhabit the park.  (It's impossible to tell the two species apart in the field.) Both male and female Pacific Coast ticks have some gray on their bodies, but the female's gray is confined to the shield portion of her back.

The soft-bodied pajahuello tick is less common in the park.  Although it's not known to carry human diseases, some people are allergic to its bite and can develop a severe reaction, with swelling, redness, and pain that take several months to disappear.

Several much less common species of ticks in the park attach to hosts that humans don't often come in contact with, and they don't seem to have developed a taste for human blood.

Catching and Feeding on Prey   (human or otherwise)

All ticks know when prey is near.  They use sense organs to detect animal scent, carbon dioxide, and heat.  The adult western black-legged and Pacific Coast ticks are usually found at the end of grass stems or other vegetation, often along trails.  They can also be found in brush.  Younger stages crawl onto prey from the ground and low vegetation.  The adult ticks wait, with their front legs outstretched, and when an animal brushes against the vegetation, the tick grabs on.  The pajahuello tick lives in gravely soil and actually looks like a piece of gravel.  It crawls along the ground and onto its prey.

Ticks cut an opening in the skin and insert their barbed snout.  The barbs make it difficult to remove the tick, and they also secrete a cement that helps keep them attached.  They inject their saliva into the cut.  The saliva contains:

		an anesthetic that keeps the prey from feeling the bite until the tick is firmly attached,
		anticoagulants that thin the blood to make it easier to slurp up,
		blood vessel dilators to increase blood flow,
		digestive enzymes to start the digestive process before the meal reaches their gut,
		and, on occasion, disease organisms.

The ticks suck the blood of their victims and drop off when they become full.  A female tick, after mating, which often occurs on the host animal, lays thousands of eggs on the ground.  The eggs hatch into larva, and after they feed for a period of time the larva molt into the nymph stage.  Both the larva and nymph stages of our hard-bodied ticks feed on the blood of lizards, birds, and small mammals.  It's extremely uncommon for the larva and nymph stages of our ticks to attach to humans.

Diseases

Ticks are vectors, which means that they pass diseases on to other animal species, and there are many diseases that ticks can carry and pass on to humans.  Lyme disease is the one that's gotten the most press though, and rightfully so.  It is the most common vector-transmitted disease in the United States.

In 1982, a scientist identified the bacteria responsible for the outbreak of a mysterious disease in Connecticut.  The disease had been misdiagnosed as rheumatoid arthritis in 1975 in a small town called Old Lyme.  The disease is not a new one.  Researchers believe that a similar tick-related disease reported in Europe about a hundred years ago was in fact the same disease.  Since the bacteria was identified in 1982, Lyme disease has been diagnosed in many parts of the world, including Asia, Africa, and Australia.

The bacteria responsible for the outbreak in Connecticut was originally thought to be transmitted by a new species of tick, which was given the scientific name Ixodes dammini.  Recently, however, the ticks have been identified as northern populations of the already described tick Ixodes scapularis, a species that's found in every state east of the Rocky Mountains.  The same tick is called a black-legged tick in the South, a deer tick in the Northeast, and a bear tick in the Midwest.  The only other tick species known to carry Lyme disease in the United States is the western black-legged tick (Ixodes pacificus), which is found in the Pacific states and in certain areas of the Southwest.

Lyme disease has been recorded in 48 states, and its incidence seems to be on the rise.  The disease is caused by a spiral-shaped bacterium called a spirochete.  In humans, early symptoms of the disease usually begin from 7 to 9 days after an infectious bite, but they can occur in as few as 3 days and as many as 30.  In about 60 percent of the cases, an expanding red rash develops, often with a clear center.  This rash, described as a "bull's-eye" rash, can grow to several inches in diameter.  The red rash that forms a few hours after a tick bite, lasts for a few days, and does not expand is not a symptom of Lyme disease.

During the first stage of the disease, people usually develop flulike symptoms, such as fever, chills, muscle and joint pain, fatigue, and loss of appetite.  Weeks or months later, during the second stage, they often suffer from severe headaches, paralysis of facial muscles, and lethargy, symptoms that normally last for several weeks and then disappear.  Months or years later, a third stage can set in, with symptoms like chronic arthritis of the larger joints, fatigue, numbness, and memory loss.

As if Lyme disease were not bad enough, ticks in California can also carry Rocky Mountain spotted fever, tick paralysis, human monocytic ehrlichiosis, human granulocytic ehrlichiosis, relapsing fever, Babesiosis, Colorado tick fever, and tularemia.

An Optimistic Outlook

The prospects are not as bleak as they may seem for outdoor enthusiasts in the West.  Although several tickborne diseases can cause dreadful illnesses and even death, their occurrences are rare.  Even the relatively common Lyme disease is much more common in eastern states than it is in the West.  In some New England states up to 60 percent of black-legged ticks carry Lyme disease, but in most of California the percentage is rarely above 5 percent, and in our area it's only about 0.5 percent.

If a tick with Lyme disease bites you and you remove the tick promptly, your chances of getting the disease are slim.  There is some disagreement about the amount of time a tick must be attached to a human before it can transmit an infectious dose of Lyme disease bacteria.  The most conservative estimate I've found is 4 hours, but the most common estimates are somewhere around 36 hours.  The reason for the delay is that the bacteria doesn't begin to multiply in the gut of the tick until the tick starts to take in blood.  Then the bacteria must enter the tick's blood system and migrate to its saliva, a journey that takes time.

In the East, humans are commonly bitten by both the adult and the nymph stages of black-legged ticks, and the nymphs are so small that people often don't know that they've been bitten.  In the West, people are rarely bitten by the nymph stage of the western black-legged tick, and if you get bitten by an adult tick, you'll most likely know it.  When the tick's anesthetic wears off, its human host usually feels a sharp sting at the site of the bite.

Science in Action

When it became known that western black-legged ticks were significantly less likely to carry Lyme disease than their eastern relatives, scientists began studying the ticks and their host animals to find out why.  Biologists decided that the low infection rate found in the western ticks was simply not high enough to keep their host animals infected and sustain the disease, so they began looking for other possibilities.

University of California biologists discovered that one of the western black-legged tick's hosts is the dusky-footed woodrat.  Then they found that the woodrat was also host to another species of tick (Ixodes neotomae), one that never bites humans.  That tick has a Lyme disease infection rate of about 15 percent, which is high enough to sustain the disease in woodrats.

The woodrat discovery was a definite breakthrough, but it still didn't explain why the western black-legged tick's infection rate was so low.  The answer to that puzzle became clear very recently.  Scientists have just discovered that western fence lizards, one of the most common hosts for the larval and nymph stages of western black-legged ticks, play a major role in reducing the incidence of Lyme disease in the West.  The lizard's blood contains a substance that kills Lyme disease bacteria.  When a tick bites a lizard, the bacteria enters the lizard's bloodstream and dies, and when the lizard's blood enters the bloodstream of the feeding tick, the tick's body is also cleansed of the bacteria.

Western black-legged ticks also feed on other rodents, including kangaroo rats, and at least one other tick is known to be a part of the Lyme disease connection.  What's more, there are different strains of the Lyme disease spirochete, another complication (and probably not the last) in the highly complex life cycle of a single disease.

Lyme Disease Diagnosis and Treatment

If you think you might have Lyme disease, see a physician as soon as possible.  The disease is usually diagnosed by the bull's-eye rash, the flulike symptoms, and knowledge that the person with the symptoms may have been bitten by a tick.  Blood tests are often used to confirm a diagnosis, but the test results are meaningless during the first several weeks following a tick bite.

Antibiotics administered during the first stage of the disease usually eliminate it entirely or at least decrease the intensity of later symptoms.  If the disease is left untreated, the later symptoms can be debilitating, but those symptoms occur in only about 10 percent of untreated cases.

Soon after Lyme disease was discovered, researchers began working on potential vaccines.  In May of 1998, the Food and Drug Administration approved a vaccine but issued restrictions on its use.  The vaccine is not to be used on people with arthritis or on children under the age of 15.  Booster shots, which may be required to maintain an immunity, are not to be given until more research is done.  The company that developed the vaccine is to continue long-term safety research.

The approved vaccine is not 100 percent effective.  A person can have an almost 80 percent chance to develop immunity but only after completion of a series of three shots taken over the period of a year.  And there are still a lot of unanswered questions about the vaccine.

The Best Defense is Good Sense

Ticks will normally grab on to one of your legs or your feet, climb up your body and under your clothes, and search for a suitable place to dig in.  To keep ticks from crawling up inside your pants legs, wear long pants, rather than shorts, and either wear gators or tuck your pants into your socks.  When you hike cross country or on narrow trails during tick season, check your legs for ticks every 10 to 20 minutes and do a full body tick check at the end of the day.  Using these precautions, you can usually keep ticks from finding their way to their preferred destinations.

For even better protection, you can use repellents containing DEET, insecticides containing permethrin, or a combination of the two.  You can apply a DEET solution on your skin, your clothing, or both to repel ticks.  Applying it on your shoes, socks, and lower legs will deter most ticks.  Permethrin, sold under brand names like Permanone and Duranon is applied to clothing.  It's not effective when used on skin because our skin deactivates it rapidly.  Permethrin will both repel ticks and kill those that come in contact with it.  When applied to clothing, permethrin's effectiveness lasts for a couple weeks and through a couple washings.

Removing Ticks

If a tick does bore into you, it's important that you remove it promptly and properly.  Several good tick removal devices are available on the market.  If you use one of them, read and carefully follow the directions.  If you don't have a removal device, you can use a pair of fine-point tweezers.  Grasp the tick as close as possible to the point of attachment and slowly and gently pull until your skin starts to lift.  Keep up the gentle pressure (without lifting farther) until the tick comes loose.  Don't twist or jerk.  If you do, you might squish the tick or break off its head or mouth parts.

If you leave part of the tick in your skin, you should have it removed by a physician.  Otherwise, you may get an infection in the bite area.  If the tick's body is squished and its body fluids get on you, it's possible that Lyme disease bacteria or other tick borne disease microbes could be absorbed through your skin.  If you don't have tweezers, you can usually grip the tick with your fingers and pull gently until the tick comes out.  If you use your fingers, wear thin gloves or hold plastic wrap or paper between your fingers and the tick.

I've made a tick removing tool that works quite well.  I started with a small twig about two and a half inches long and an eighth of an inch in diameter.  I split the twig down about half its length and carved curved notches in the ends so that when you grasp a tick with it and lock the two halves together, the tick is caught, but not squished, in between.  The tool is designed for spinning, rather than pulling.  A quick spin and the tick is out.

After you remove a tick, use an antiseptic on the wound and wash your hands and tools.

Some people still believe that you can get a tick to back out by putting petroleum jelly, nail polish, a drop of kerosene, or other chemicals on it, or by lighting a match, blowing it out and applying the hot tip to the tick's body.  I've never known any of these methods to work.  The only result I've seen when they're used is a maimed or dead tick that's still attached.  Research in such methods has yielded the same results.

Take a Hike

There's no reason to deprive yourself of trips into the Coe backcountry.  Knowledge dispels unwarranted fear.  Just remember:

		You can avoid areas where you might pick up ticks.
		If ticks gets on you, you can easily pick them off, especially if you've dressed to keep ticks outside your clothing.
		Since ticks normally don't attach for several hours, you can usually find any that escaped earlier tick checks by doing a full-body tick check at the end of the day.
		You can greatly reduce the chances a tick will get on you by using special repellants and insecticides.
		In Coe Park, only one in 200 ticks carries Lyme disease, and if one of those ticks bites you, prompt and proper removal of the tick will keep you from becoming infected.
		And, finally, even if you do get a tick bite followed by Lyme disease symptoms, you can get early treatment to eliminate the disease.

.   .   .   .  Her long journey continued. She reached an outermost branch of the blue oak tree about six hours later. As she gazed down she saw the blurry image of a man pausing on the trail right below her. He was not too fast, he was not too small, and he wasn't that far away (closer than the deer was anyway). She leaped into the air and dived towards her unsuspecting prey. Her target was the man's neck, but at the very last moment he leaned over to check his legs for ticks. The flying tick missed by a mere quarter inch and landed with a thud on the hard dirt of the trail. "Curses!" she muttered.  But nobody heard.

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