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Tick-borne diseases, like those carried by this deer tick,
are on the rise. E. R. Degginger photo, courtesy
of National Geographic
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Avoid
Tick-Borne Diseases
By
Robert E. Thomas
John Tharp caught a lot more on his fishing
trip than he ever wanted.
While fishing on a lake in Dixon, Mo., in May, Tharp, 59, of Columbia,
received a tick bite. Eight days later, he became terribly ill
with a high fever, upset stomach, vomiting and complete malaise.
A doctor diagnosed his condition as ehrlichiosis, a tick-borne
disease, and prescribed a regimen of antibiotics. Tharp had to
cancel a long-planned vacation to Ireland. His doctor said full
recovery may take three months to a year, he said.
Fifty-six cases of ehrlichiosis have been reported in Missouri
since early July, more than double the total number of cases reported
in 2006. The number of reports of tick-borne Rocky Mountain spotted
fever, Lyme-like disease and tularemia also are up, according
to the Missouri Department of Health and Senior Services.
These diseases can be life-threatening and difficult to diagnose,
said Dr. Bao Ping Zhu, Missouri state epidemiologist. One death
of a child has been reported this year in Missouri.
“It is not common to get a tick disease. If you think about
the thousands of tick bites people get, it is a low percentage.
Yet, tick bites can be very serious. To transmit a disease, ticks
would have to have fed on a host that has that bacterium in it,” said Richard Houseman, MU
Extension entomologist.
Circle on a calendar the day you received a tick bite, and monitor
your health for the next two weeks for nausea, chills, fever or
malaise. If any of these symptoms appear, seek medical help, he
said.
The lone star tick and the dog tick are Missouri's most prevalent
ticks. The lone star tick can transmit STARI or Southern Tick-Associated
Rash Illness, tularemia or rabbit fever, and ehrlichiosis. The
dog tick can transmit tularemia and Rocky Mountain spotted fever.
Make frequent tick checks. Tick diseases cannot be transmitted
unless the insect is embedded for four to six hours.
Proper tick removal is important. “Grasp the tick at its
mouth part next to your skin with sturdy, narrow tweezers and
pull firmly, allowing the skin to pull away from the tick,” he said.
Do not try removing a tick with your fingers. “Your fingers
may squeeze the body of the tick making it act like a hypodermic
needle shooting bacteria into your blood,” he said.
The
American dog tick, left, and Lonestar tick are Missouri's
most common ticks. Richard Houseman photo
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Houseman suggests several approaches to protect from tick bites.
The most effective defense when outdoors is to tuck your pants
into your socks to keep ticks on the outside of your clothing.
Ticks can get under your pant leg. They have a natural tendency
to travel upward when they get on a host.
Use repellents for protection. DEET and a new product, Picaridin,
are recommended by the World Health Organization. Apply these
products every four hours. Never wear a flea or tick collar like
those used on pets. Pet collars can cause serious skin burns.
Ticks like tall grass, shrubs close to the ground and dense vegetation,
especially along boundary areas, he said.
“Keep your grass mowed to a height of three inches, allowing
air circulation around the base of the grass,” he said.
“Ticks dry out quickly in midday if exposed to heat and dry
conditions. During those times, they go down to the base of the
vegetation close to the soil. They close off their breathing holes
and ride out that hot, dry time.” Ticks become most active
in the morning or evening when the air cools and humidity rises,
he said.
Ticks require three hosts. After hatching from eggs, they must
find a small host; usually a rabbit or other rodent.
They then must molt and drop off that host to get a blood meal
from a second host. Usually, that is a bigger host like a raccoon
or possum. They molt again and drop off to find a third host,
he said.
“The more hosts there are around, the more likely ticks are
to complete their life cycle,” he said. “Host management
is really critical. In fact, studies show deer populations and
tick populations almost mirror each other. Some people encourage
wildlife in their backyard, but the more it is encouraged, the
more they must expect to come in contact with ticks.”
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Last Update:
March 12, 2007
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