Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Deer Tick Encephalitis

Deer Tick PicturesA fatal case of deer tick encephalitis (inflammation of the brain) was recently reported by Norma Tavakoli and colleagues in the New England Journal of Medicine (N Engl J Med 2009;360:2099-107).

Deer tick virus is a member of the tickborne encephalitis group of flaviviruses. It is closely related to Powassan virus. While infection with tickborne encephalitis virus may be asymptomatic or mild, it can be quite devastating, leading to meningitis, encephalitis, and, we now know, death. Other flaviviruses that cause human diseases are West Nile virus, St. Louis encephalitis virus, dengue (fever) virus, and yellow fever virus. These are commonly transmitted by mosquitoes.

This case emphasizes that deer tick-borne diseases, such as deer tick encephalitis, babesiosis, anaplasmosis, and Lyme disease, can be serious, life-threatening illnesses. Persons who frequent the outdoors should take appropriate precautions via proper clothing, insect repellent, and skin inspection, to avoid tick bites. Since nymphal deer ticks capable of transmitting disease can be quite small (1.5 mm in diameter), it is understandable how they might be missed on a casual skin or hair-covered area inspection. Furthermore, unless there is a local reaction, a bite may go unnoticed. It is therefore crucial to bathe and scrub vigorously at frequent intervals when in “tick country,” and to engage the assistance of a companion to visually inspect any body areas in which you suspect the presence of a tick.

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Preview the Annual Meeting of the Wilderness Medical Society, which will be held in Snowmass, Colorado July 24-29, 2009.

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.