Minnesota Orienteering Club: A Word About Protection

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A Word About Protection

by Georgia Nothdurft, MSc, RPA-C

Winter is waning; spring, wet, cool and muddy, approaches. We anticipate returning to our favorite sites for challenging events, eager to begin the competitive year. Anticipating our arrival is the lowly tick. Of particular interest is the black-legged, or, deer tick (Ixodes scapularis), the vector for Lyme disease, Human Anaplasmosis (Ehrlichiosis), and Babesiosis.

The Minnesota Department of Health (MDH) lists the counties of Hubbard, Cass, Aitkin, Crow Wing, Pine, Kanabec, Mille Lacs, Morrison, Isanti, Sherburne, Anoka, Chisago, Washington, Wabasha, Winnona, Houston and northern Ramsey as high risk for tick-borne disease. This region is geographically intimate with the Mississippi River drainage. However, the last deer tick study (2005) found ticks positive for B. burgdorferi (the causative agent of Lyme disease) in Olmsted, Filmore, Wright, Stearns, Todd, Wadena and Becker counties. It is the opinion of the MDH that an expansion of tick-borne disease is occurring in the state. Minnesota ranks 8th in the nation for confirmed Lyme disease cases.

Adult deer tick

The greatest risk for human exposure to tick borne illness occurs from late spring into the first hard frost of autumn. Most of us are aware of the bulls-eye rash (Erythema migrans) associated with infection with Lyme disease. It is generally believed to occur in less than 50% of cases. Therefore the lack of a rash after activity in a known tick environment does not prove non-infection. Nymph (juvenile) ticks are more likely to transmit the disease. Although a smaller percentage of nymphs, compared to adult ticks, are infected, their small size (equal to the period at the end of this sentence) makes it more difficult to identify them on your clothing or body. Therefore the best protection is prevention.

Babesiosis and Ehrlichiosis (Human Anaplasmosis), both lesser known tick diseases, are found in Minnesota. Co-infection with two or all three diseases has been noted by the MDH. The number of reported cases of Ehrlichiosis, a bacterial disease, has increased 300% since 1999. Clinical features of Ehrlichiosis (HA) generally include fever, headache, fatigue, and muscle aches. Other signs and symptoms may include nausea, vomiting, diarrhea, cough, joint pains, confusion, and occasionally rash. Symptoms typically appear after an incubation period of 5-10 days following the tick bite.

Babesiosis is a protozoan disease, whose symptoms closely resemble malaria (high fever, aches, chills, headache, fatigue and loss of appetite). Like malaria, Babesiosis infects human red-blood cells. This is a new disease in Minnesota, with 9 cases in 2005, and 18 in 2006. The actual number of cases is not known, as some cases may be asymptomatic.

A moment of prevention is worth 3 months of cure. Wear light colored clothing when possible. Tuck shirt tails in, and wear socks (or gaiters) over pants. Use an EPA approved tick repellant. This should be applied to those body parts likely to be exposed to the vegetation harboring questing ticks. In a wet environment, including human sweat, applications must be more frequent. Permethrin 0.5% based spray (on clothing only, not on skin) is an insecticide, not a repellent. It will kill ticks on contact, and prevent transporting ticks on clothing. Pretreated Permethrin clothing is available (Buzz Off by Ex Officio).

Untreated clothing should be removed as rapidly as possible, and placed in a plastic bag. Ticks quest (seek a host) by detection of heat, movement and CO₂. They will rapidly abandon the gaiters casually tossed in the back seat, and begin an epic migration to any unprotected patch of flesh accessible on the passengers within an automobile.

Tick borne disease is on the geographic move in Minnesota. With education, and prevention, the number of cases does not have to accompany the march of infected ticks. Let’s enjoy a safe, healthy and successful orienteering season.

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