Question of the Week

July 11, 2005


"Toward the end of the 19th century, scientists began to understand the important potential for ticks to act as transmitters of disease."

What are ticks?

"Ticks are blood feeding external parasites of mammals, birds, and reptiles throughout the world. ... There are two well established families of ticks, the Ixodidae (hard ticks), and Argasidae (soft ticks). Both are important vectors of disease causing agents to humans and animals throughout the world. Ticks transmit the widest variety of pathogens of any blood sucking arthropod, including bacteria, rickettsiae, protozoa, and viruses. Some human diseases of current interest in the United States caused by tick-borne pathogens include Lyme disease, ehrlichiosis, babesiosis, rocky mountain spotted fever, tularemia, and tick-borne relapsing fever."

How do ticks transmit diseases to people?

"Often these diseases are transmitted by the ticks saliva during feeding behavior.  However, some diseases, such as tularemia, can enter through the skin if a person comes into contact with a crushed infected tick.  In recent years, Lyme disease has become the most reported arthropod borne disease in the country."

Lyme disease typically gets some press each year.

"Lyme disease was named in 1977 when arthritis was observed in a cluster of children in and around Lyme, Connecticut. ... Further investigation revealed that Lyme disease is caused by the bacterium, Borrelia burgdorferi. These bacteria are transmitted to humans by the bite of infected deer ticks ... In the United States, Lyme disease is mostly localized to states in the northeastern, mid-Atlantic, and upper north-central regions, and to several counties in northwestern California. In 2002, 23,763 cases of Lyme disease were reported to the Centers for Disease Control and Prevention (CDC)..."

But Lyme disease is not the only disease that humans can contract as a result of contact with ticks.

"Ehrlichiosis [air-lick-ee-OH-sis] is a newly recognized bacterial disease that is spread by infected ticks. Two types of human ehrlichiosis have been identified in the United States: human monocytic ehrlichiosis [HME] and human granulocytic ehrlichiosis [HGE].
* Most infections are mild or without symptoms, but some can be severe and life-threatening.
* Ehrlichiosis can usually be treated with antibiotics.
* Prevention centers on avoiding exposure to ticks and removing attached ticks promptly."

"Babesiosis [bab-EE-see-OH-sis] is a rare parasitic disease that is transmitted to people by infected ticks.
* Babesiosis occurs mainly in coastal areas in the northeastern United States, especially the offshore islands of New York and Massachusetts.
* Elderly persons and people with weakened immune systems can get severe complications from babesiosis.
* No vaccine against babesiosis is available. To prevent babesiosis, avoid exposure to ticks, and remove attached ticks right away. ... Babesiosis in humans is a rare, potentially fatal disease that is transmitted by the bite of an infected tick. Babesiosis is a common infection in animals."

But not all tick-borne illnesses are transmitted only as the result of a tick bite.
"People can get tularemia many different ways:
* being bitten by an infected tick, deerfly or other insect
* handling infected animal carcasses
* eating or drinking contaminated food or water
* breathing in the bacteria, F. tularensis
Tularemia is not known to be spread from person to person. People who have tularemia do not need to be isolated. People who have been exposed to the tularemia bacteria should be treated as soon as possible. The disease can be fatal if it is not treated with the right antibiotics."

Just a few of the illnesses that are transmitted by ticks have been mentioned here. No matter what illnesses people are trying to avoid, staying away from the ticks themselves is often the best way to stay away from the diseases they transmit.

With that in mind:

"Outdoor pursuits need not be discontinued as long as precautions are taken to prevent a tick bite:
* avoid tall grass and shrubbery areas
* wear light-colored clothing (ticks are easier to see)
* wear long pants tucked into socks
* widen trails through woods (to 6 feet)
* remove brushpiles
* keep turfgrass mowed
* thin out low shrub vegetation in woods
* wear a tick repellent"

Even if all precautions are taken, tick bites are still possible. If someone does get bitten by a tick, it is best to:

"Remove ticks with tweezers only (bent, 'needle-nose' tweezers are best).  Apply steady backward force until the tick is dislodged.  Do NOT use alcohol, nail polish, hot matches, petroleum jelly or other methods to remove ticks.  These methods may actually traumatize ticks, causing them to regurgitate their gut contents, which may include the Lyme disease bacterium. Save the live tick for identification..."

Questions of the Week:
What do you need to know about ticks and the diseases they transmit -- regardless of where you live? Do you live in an area where ticks are common? Are ticks in your area thought to carry disease? Whether or not they are common where you are, what precautions would make sense for you to take when heading outside? While outside, what can you do to reduce your risk of possible exposure to illnesses transmitted by ticks? When coming in from the outdoors, what can you do to check for possible exposure to ticks? If you have been exposed to a tick, what should you do? What should you not do?

Please email me with any ideas or suggestions.
Note: Due to increasing amounts of SPAM sent to this account, please include "QOW" in the subject line when sending me email.

I look forward to reading what you have to say.

Health Community Coordinator
Access Excellence @ the National Health Museum

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