Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

Wilderness and Rescue Medicine 186

The most common and troubling mite infesta- tion is scabies (Sarcoptes scabiei). Humans are the normal host where the mite enjoys a full life cycle in the outer layers of the skin. Scabies is usually passed between people by skin-to-skin contact. The symptoms begin with a few small and intensely itchy red spots that slowly spread over days or weeks to involve other body areas, especially where the host human can scratch and spread eggs from one site to another. Epidemics within close groups or families is common. A host can begin to spread scabies before symptoms become apparent. Secondary bacterial infection is an anticipated problem.

by insect repellents and insecticides. Your own sleeping bag, frequently washed, is another good defense.

Human louse Lice are easily transmitted between people sharing clothing and furniture. They tend to limit their range to groin or head hair. The adults are easily killed with permethrin or malathion. Reapplication may be necessary in 10 days to kill the newly hatched larvae. In the absence of per- methrin shampoo, lice can also be smothered with a layer of any viscous substance such as Vaseline or mayonnaise. It may not be pretty, but it can solve your problem.

Scabies often appears first on the hands Treating scabies requires application of 5% per- methrin cream or other topical scabicide that is left on the skin for several hours. Bedding and clothing can be treated with a hot dryer. Preferably the patient, clothing, and bedding are treated simultaneously to prevent repeat infestation. Insect Repellents The best insect repellents currently available include DEET, permethrin, picaridin, and IR3535. DEET and permethrin are both extensively stud- ied and are considered safe and effective. DEET can be used on the exposed skin of hands, ankles, and the face. There is no advantage to using a for- mulation greater than 30% DEET. Permethrin is recommended for clothing and has been shown to remain effective after 20 or more washings. Both DEET and IR3535 can damage plastics and irritate the eyes. Lotion formulations of either

Nit of a louse on a hair Mites can be a bit more difficult to identify and treat. Most are too small for the naked eye to see and can cause a variety of rashes. Most mite infes- tations are self-limiting because the human is not the normal host. The mite may feed temporarily and drop off without burrowing or reproducing. The rash disappears when contact with the host organism is discontinued.