Wilderness and Rescue Medicine 8th Edition

185

Section V: Environmental Medicine

Ticks serve as a vector for diseases from anaplas- mosis to ehrlichiosis and varieties of spotted fevers and encephalitides worldwide. One tick can carry multiple diseases. Fortunately for the medic on a short expedition, most of these conditions mani- fest themselves many days to weeks after exposure. Unfortunately for the patient and their doctor, these diseases present with a constellation of confusing symptoms making a definitive diagnosis difficult. The primary work of the practitioner in the field is prevention and education. Inform your teammates or expedition members of the risks involved in hosting ticks. Instruct them to wear long-sleeved shirts with long pants tucked into high socks, and a bandanna high on the neck under a low hat. Encourage the use of repellent on clothing, especially around cuff and neck openings. Following these recommenda- tions, your teammembers may look silly, but they will substantially reduce the chance of feeding a tick and acquiring a tick-borne disease. It is also important to check for ticks frequently on your skin and clothing. Wearing light-colored clothing will help. They usually crawl around for a while before settling in to feed. Frequent inspections will get rid of most of them before they attach.

Tick Paralysis The saliva of some species of ticks contains a neu- rotoxin capable of causing symptoms in humans, most commonly in children. Tick paralysis can develop after 4 or more days of attachment and is characterized by numbness and paralysis pro- gressing up the legs and arms. The patient may exhibit ataxia (stumbling gait), restlessness, or irritability. The diagnosis is suspected by find- ing an engorged tick and confirmed by rapid improvement following its removal. Tick paralysis is rare but can cause fatal respira- tory paralysis if the tick is not found and removed. Ticks are more commonly implicated as vectors of bacterial and parasitic disease. Prevention of tick paralysis and tick-borne disease depends on avoiding bites and early removal of attached ticks. Arthropod Disease Vectors The phylumArthropoda includes insects, spiders, crustaceans, and others that comprise over 80% of known animal species. Since many arthropods feed on humans, they are a significant disease vec- tor. Some arthropods merely transmit viruses or bacteria from person to person. Others serve as a host for one stage of the parasite life cycle with humans hosting another. In either case, illness is often, but not always, the result.

Tick-borne Disease

General Principles

30

Prevention:

• • • • • • DEET, Picaridin, or IR 3535 on skin Permethrin on clothing Tight weave clothing Frequent tick checks Prompt removal of attached ticks Post-Exposure Prophylaxis in Lyme endemic regions

*

“Tick country" is vegetated: woods, grass, and brush. Tick season is spring, summer, and fall.”

© 2018 WMA

Ticks that are attached can be most safely removed by grasping them at the skin surface and gently pulling them off with tweezers. Sometimes, the mouth-parts break off and remain in the skin. Try to scrape these out with a sharp blade or needle. The host should not attempt removal by burning the tick, or by suffocating or poisoning it with

Adult deer tick