 Lyme Disease
BNL has the three closely interrelated elements that must be
present in the natural environment for Lyme disease to exist
in the area: animals that carry Lyme disease bacteria, ticks
that transmit the bacteria, and mammals (such as mice and
deer) that provide food for the ticks in their various life
stages.
Lyme disease was first recognized in the United States in 1975, after a mysterious
outbreak of arthritis near Lyme, Connecticut. Since then,
reports of Lyme disease have increased dramatically, and the
disease has become an important public health problem in some
areas of the United States.
Lyme disease is an infection caused by the corkscrew-shaped
bacterium Borrelia burgdorferi, a member of the
family of spirochetes. The bite of ticks spreads the bacterium
that causes Lyme disease. The black-legged (or deer) tick,
Ixodes scapularis, which normally feeds on the
white-footed mouse, the white-tailed deer,
others mammals, and birds, is responsible for transmitting Lyme disease
bacteria to humans in the northeastern and northcentral United States. On the
Pacific Coast, the Lyme disease bacteria are transmitted to
humans by the western black-legged tick, Ixodes pacificus,
and in the southeastern states, possibly by the black-legged
tick, Ixodes scapularis.
Ixodes ticks are much smaller than the common dog and cattle ticks.
In their larval and nymphal stages, they are no bigger than
the eye of a common sewing needle. Adult ticks are larger,
about the size of a small apple seed.
Nymphal ticks are the primary source for transmitting Lyme
disease bacteria to humans, probably because nymphs are more
likely to feed on people and are rarely noticed because they
are tiny (less than 2mm). Thus, nymphs have the necessary time
to feed and transmit the bacteria, typically after feeding for
2 or more days. Also, nymphal ticks feed during the spring and
summer months when people spend the most time outdoors.
Adult ticks can also transmit the bacteria, but because
adult ticks are larger and more noticeable, they are more
likely to be removed from a person’s body within a few hours,
and therefore are less likely to have sufficient time to
transmit the bacteria. Moreover, adult Ixodes ticks
are most active during the cooler months of the years, when
people spend less time outdoors and additional clothing may
provide added protection.
Ticks can attach to any part of the human body but are
often found in hard to see and hairy areas such as the groin,
armpits, and scalp. In most cases, the tick must be attached
for 48 hours or more before the bacteria can be transmitted.
Ticks search for host animals from the leaf litter of the
forest floor (nymphs) or from the tips of grasses and shrubs
(adults) and crawl on to animals or persons they contact.
Ticks do not fly or jump. Ticks found on the scalp usually
have crawled there from lower parts of the body. Ticks feed on
blood by inserting their mouth parts (not their whole bodies)
into the skin of a person or animal. They are slow feeders; a
complete blood meal can take several days. As they feed,
their bodies slowly enlarge.
Personal protection from tick bites
You can decrease the chances of being bitten by a tick by
following a few precautions.
- Avoid tick-infested areas, especially in
May, June and July (many local health departments and park
or extension services have information on the local
distribution of ticks).
- Wear light-colored clothing so that it is
easier to spot ticks.
- Tuck pant legs into socks or boots and
shirt into pants.
- Tape the area where pants and socks meet
so that ticks cannot crawl under clothing.
- Wear a long-sleeved shirt and pants
instead of shorts for added protection.
- Spray insect repellent containing a
20-30% concentration of DEET on clothes and on exposed skin
other than the face, or treat clothes (especially pants,
socks, and shoes) with permethrin, which kills ticks on
contact.
- Walk in the center of trails to avoid
contact with overgrown grass and brush at trail edges.
- After being outdoors, remove your clothing and wash and
dry it at high temperature.
- Inspect your body carefully and remove attached ticks.
This can be done with tweezers, grasping the tick as close
to the skin surface as possible and pulling straight back
with a slow steady force. Avoid crushing the tick's body.
- Use insect repellants such as Bio-Spot on dogs
accompanying you out doors to prevents tours pets from
bringing tides indoors
For detail information on Lyme disease contact the
Centers
for Disease Control and Prevention
Last Modified: November 14, 2008
Please forward all questions about this site to:
Karen Ratel
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