Avoiding Ticks and Lyme Disease

Background

Geologists and others who work in the field should have some knowledge about ticks and tick-borne diseases. If left untreated, Lyme disease, caused by tick bites, can cause chronic neurological problems and severe joint pain that can persist for years after the initial infection.

Outdoor workers should know how to recognize ticks, avoid tick bites and recognize the early signs of Lyme disease. Early treatment with antibiotics can produce a rapid and complete recovery.

Recognizing Ticks

The bacteria responsible for Lyme disease, Borrelia burgdorferi, normally lives in mice, squirrels and other small animals. It is transmitted from one animal to another through the bites of certain species of ticks. The black-legged tick (or deer tick, Ixodes scapularis) and the western black-legged tick (Ixodes pacificus) both can carry and transmit the disease. (See photograph and illustration at right.)

Life Cycle of Blacklegged Ticks

Blacklegged ticks live for two years. They lay eggs in the spring and those eggs hatch as larvae that summer. The larvae feed by biting small animals and consuming their blood. If the animal is infected with Lyme disease bacteria, the tick ingests them and becomes infected. The larvae progress to the nymph stage by the following spring.

In the spring the ticks are very active and searching for another blood meal. When the tick feeds again it transmits bacteria into its host. The host is usually a rodent, however, this is the stage when humans are usually bitten.

These bites usually occur in the late spring and summer. This is the time of year when humans should take the greatest precaution.

The nymphs progress to adult stage in the fall. Adult ticks usually feed on large animals and sometimes on humans. In the spring, the adults lay their eggs on the ground and their life cycle is complete.

Geographic Range of Blacklegged Ticks

The blacklegged tick has a geographic range across the eastern and southeastern United States and in the Great Lakes region. The western blacklegged tick has a range that spans the Pacific coast and some inland areas of Washington, Nevada, Arizona and Utah. (See geographic range map at right.)

Avoiding Tick Bites

The Center for Disease Control offers the following advice for avoiding tick bites:

Avoid Areas Where Ticks Live

Ticks live in wooded and brushy areas with abundant leaf litter. They also live in high grass. Avoid these areas.

Take extra precautions in May, June and July. This is when the ticks that transmit Lyme disease are most active.

If you walk through a tick area, walk in the center of the trail and avoid contact with grass, trees, brush and leaf litter.

Ask your local health department and extension service about tick infested areas to avoid.

Keep Ticks Off of Your Skin

Use insect repellent with 20% - 30% DEET on exposed skin and clothing to prevent tick bites. Effective repellents are found in drug, grocery and discount stores.

Permethrin is another type of repellent. It can be purchased at outdoor equipment stores that carry camping or hunting gear. Permethrin kills ticks on contact! One application to pants, socks, and shoes typically stays effective through several washings. Permethrin should not be applied directly to skin.

Wear long pants, long sleeves, and long socks to keep ticks off your skin. Light-colored clothing will help you spot ticks more easily. Tucking pant legs into socks or boots and tucking shirts into pants help keep ticks on the outside of clothing. If you'll be outside for an extended period of time, tape the area where your pants and socks meet to prevent ticks from crawling under your clothes.

Check Your Skin and Clothes Daily

Remove ticks from your clothes before going indoors. To kill ticks that you may have missed, wash your clothes with hot water and dry them using high heat for at least one hour.

Perform daily tick checks after being outdoors, even in your own yard. Inspect all parts of your body carefully including your armpits, scalp, and groin. Remove ticks immediately with fine-tipped tweezers. (See illustration at right.)

If a tick is attached to your skin for less than 24 hours, your chance of getting Lyme disease is extremely small. But just to be safe, monitor your health closely after a tick bite and be alert for any signs and symptoms of tick-borne illness.

Tick Removal

When a tick bites it usually holds fast to its host. They can be very difficult to remove. Here are some tips for removing a tick provided by the Center for Disease Control:

Remove a tick from your skin as soon as you notice it. Use fine-tipped tweezers to firmly grasp the tick very close to your skin. With a steady motion, pull the tick’s body away from your skin. Then clean your skin with soap and warm water. Throw the dead tick away with your household trash.

Avoid crushing the tick’s body. Do not be alarmed if the tick’s mouthparts remain in the skin. Once the mouthparts are removed from the rest of the tick, it can no longer transmit the Lyme disease bacteria. If you accidentally crush the tick, clean your skin with soap and warm water or alcohol.

Don’t use petroleum jelly, a hot match, gasoline, nail polish, or other products to remove a tick.

Lyme Disease Symptoms

Lyme disease symptoms vary from one person to the next. If you suspect that you have symptoms it is VERY important to see a physician immediately.

In most people, the first sign of an infection is a circular rash that often appears as a bull's-eye pattern around the site of the bite. This rash usually appears within 3 to 30 days after the bite occurs. (See photo at right.) The rash usually expands over a few days and is sometimes warm to the touch. An infected person may also experience symptoms such as fatigue, headache, fever, muscle aches, joint pain or swollen lymph nodes.

Treatment should be sought right away if you have the above symptoms. The disease is usually easy to cure if treated during the first few weeks. If it is allowed to progress, severe neurologial and joint problems can result and these can persist for years.

Lyme Disease History

The first recognized case of Lyme disease in the United States was in 1975. An unusual outbreak of severe arthritis near Lyme, Connecticut called attention to the disease. Since then the number of cases reported has been steadily increasing. (See chart at right.)

Lyme Disease Geography

Most cases of Lyme disease are concentrated in a few areas, however, cases have been reported in all 50 US states. Most infections occur in the northeast, in the Great Lakes region and along the Pacific coast (See incidence map at right.) Lyme disease can occur anywhere that infected animals live together with ticks that can transmit the bacteria.

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