Under what wilderness conditions is becoming infested with lice a possibility and what precautions should one take to avoid it?

Question

I may have reacted without thinking to the question about dealing with lice because I have never worried about getting lice on a wilderness trip.

Upon reflection, I find I am genuinely interested in knowing under what wilderness conditions lice are a possibility and what reasonable precautions I could take to avoid being colonized by the critters.

"Reasonable" differs from person to person; I wouldn't consider shaving off all my head and body hair reasonable unless the probability of becoming infested was pretty high, but I can't quantify "pretty high" when the problem is still abstract.

Most of my backpacking has been in the Sierra and Rockies, most of the time above timberline, there's been some in Hawaii and a bit in Shenandoah. And believe me, I have emerged filthy from two-week-plus trips, but lice-free. Would it have been a different story for a much longer trip, or a trip in a very different environment?

Answer 1

Lice are passed on by one of two manners. Either by direct contact or indirect contact with someone who is infected with lice.

The chances of coming in contact with lice in the wilderness is exceedingly remote. A camp site that has been abandoned for several days would be free of lice if it was actually occupied by an infested person.

First of all, there is no need to spray your home and belongings with potentially dangerous insecticides. Lice are known as “obligate parasites,” meaning they don’t survive very long without their human host. They need us to live, and they die within 24 to 48 hours after removal from a human host. - How to Keep Lice from Spreading—and Coming Back!

Here is how people actually get lice:

Head lice move by crawling; they cannot hop or fly. Head lice are spread by direct contact with the hair of an infested person. Anyone who comes in head-to-head contact with someone who already has head lice is at greatest risk. Spread by contact with clothing (such as hats, scarves, coats) or other personal items (such as combs, brushes, or towels) used by an infested person is uncommon. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice. - Who is at risk for getting head lice?

If one really encounters lice in the great outdoors, either someone in the group brought the infestation with them or one is camping (very remote possibility) in camp that had been infested by others within 48 hours of the infested person leaving.

Basically what I am saying is that someone in a hiking group brought the lice into the wilderness with them if an infestation occurred at all.

Update: My same thought still holds for body lice.

Without a constant source of blood, the lice perish within 2-5 days. In hot weather, when several layers of infested clothing are worn, the lice may move to an outer layer where the temperature is cooler. Lice are very rarely seen crawling on the outside of infested clothes, if they are visible it is an indication the individual is heavily infested. Normally body lice are sensitive to light and if disturbed will quickly move to a seam or crease for cover. - Department of Medical Entomology

Body lice too are transmitted by contact:

Body lice are spread through direct physical contact with a person who has body lice or through contact with articles such as clothing, beds, bed linens, or towels that have been in contact with an infested person. In the United States, actual infestation with body lice tends to occur only in persons, such as homeless, transient persons, who do not have access to regular (at least weekly) bathing and changes of clean clothes, such as homeless, transient persons. - How are body lice spread?

In a truly wild area, I believe such an infestation would not be found, regardless of what type of lice is involved.

Answer 2

There are many different kinds of lice, but only three species can colonize humans. Lice are strongly adapted to a particular species and don't cross infect other species. They are also "obligate" parasites, meaning they can survive only a limited time away from a host. That means that you are less likely to develop a louse infestation in areas where human population density is low, i.e. wilderness. Human louse infestations are associated with crowding and intimacy. Really the only way you are going to develop a louse infestation in the wilderness is if someone in your party entered the wilderness already infested.