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. (See illustration below.)
Life Cycle of the Blacklegged Tick (Deer Tick)
Graphical representation of the two-year life-cycle of the blacklegged tick. People are at greatest risk of infection while the tick is in its nymphal stage during the spring and summer of its second year with additional risk from adult ticks in the fall of its second year. Center for Disease Control.
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. (See life-cycle graphic above.)
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 as close to your skin surface as possible. (See image at right.) With a steady even 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 rubbing alcohol.
Don’t use petroleum jelly, a hot match, gasoline, nail polish, or other products to remove a tick.
After the tick is removed wash your hands and the bite location thoroughly with soap and water or rubbing alcohol. Clean the tweezers with rubbing alcohol.
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.
Staying Safe from Ticks and Lyme Disease
Learn about ticks and Lyme disease to improve your chance of avoiding infection.
Photograph of a black-legged tick, also known as a deer tick (Ixodes scapularis).
Image by the National Institute for Occupational Safety and Health / Center for Disease Control.
Common Ticks and Their Life Stages
Graphic showing common types of ticks and their appearance at different stages of their life cycle.
Image by the National Institute for Occupational Safety and Health / Center for Disease Control.
Geographic Range Map - Lyme Disease Ticks
Map showing the geographic range of the blacklegged tick and the western blacklegged tick.
Map by Geology.com using data from the Center for Disease Control.
Mapping Tick Habitats with Satellite Data
This video that explains how NASA scientists are able to map the most probable areas of tick occurrence using satellite data.
How to Remove a Tick
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. (For more details see information at left.) Illustration by
the Center for Disease Control.
Lyme Disease Rash - Bull's Eye Pattern
Photograph of the circular rash known as "erythema migrans" that is often present in the early stage of
Lyme disease. Note the "bull's-eye" pattern that surrounds the site of the tick bite. Lyme disease patients who are
diagnosed early, and receive proper antibiotic treatment, usually recover rapidly and completely. Photograph by
James Gathany, Center for Disease Control.
Reported Cases of Lyme Disease in the US
State health departments reported 28,921 confirmed cases and 6,277 probable cases of
Lyme disease to CDC in 2008. This represents a 5% increase in confirmed cases compared to 2007. The definition
and reporting of probable cases was initiated in 2008 based on revisions to the national surveillance case
definition. Chart by the Center for Disease Control.
Lyme Disease Incidence Map
Map showing the incidence of Lyme disease in the United States.
Values are the number of confirmed cases per 100,000 population.
Map by Geology.com using data from the Center for Disease Control.
Lyme Disease Map
Map showing the incidence of reported cases of Lyme disease in the 48 states.
One dot was randomly placed within the county of residence for each reported case.
Map by the Center for Disease Control.
More Information for Ticks and Lyme Disease
[1] Lyme Disease: Some of the most comprehensive and trusted information on the web for Lyme Disease can be found at the Center for Disease Control and Prevention website.
[2] Preventing Tick Bites: How to avoid tick bites on people and on pets from the Center for Disease Control and Prevention, website article, 2011.
[3] Tick Removal: Don't panic. This article on the CDC website explains exactly what to do to remove a tick. Center for Dease Control and Prevention, website article, 2011.
