An email from the American Academy of Dermatology came to my inbox as a reminder about detecting head lice, one of the common scourges of younger school kids.

So, I figured it might be worth reviewing detection tips and techniques to start the academic year off with a burst of paranoia, along with what teachers the kiddos get, who will pick on them, etc.

This discussion is only about detection and diagnosis, not treatment, which is a long subject by itself. Somebody declared September lice prevention month. Whoopee.

Pediculus humanus capitis, the head louse, has been with hominids since before doctors had offices or caves were heated. The incidence of it in any population seems to rise and fall over periods. There is a suspicion that heads that are infested produce some obscure sort of immunity in the group or “herd” (Think of a playground full of urchins wrestling, etc, as the herd.).

Head lice are medically harmless. They carry and transmit no diseases. They cause itchy noggins and paranoid parents and teachers. For the older hands (and heads), not so much. Been there, done it. If there is enough scratching, some lucky bacteria can infect the scalp a bit. In the United States, the predominant populations infested are pre-school and elementary-age children, their caretakers and household members.

Reliable data about how many kids get lice are not available, but guesstimates are 6-12 million children ages 3-11, according to the Centers for Disease Control. A few studies suggest girls might be more “blessed.” For reasons that are a total mystery, occurrence in African-Americans is much less common.

Infestations can be asymptomatic, or not create itch for four to six weeks. Itch is by far the most common feeling, primarily along temples, back, scalp and behind ears. The lice don’t inhabit the upper crown area very frequently, again a mystery. The lice do not migrate to other body areas, nor do they jump from person to person or to any animals. They like people exclusively.

The life cycle of a louse has three stages. First is the egg, or nit, an old word for exactly that. They are 0.8 by 0.3 mm and hard to see. With the baby inside, the color is kind of caramel to white. After hatching, it is more white.

The mom lays up to eight nits a day and cements them to the base of hair shafts with a substance stickier than any glue we have made. They hatch in about one week. Then they become nymphs the size of pinheads with the same shape as adults. After three “molts” they become mommy and daddy lice, with six legs, about the size of sesame seeds and appear gray-white to tan. They can live up to 30 days in the host’s cranial penthouse, feeding on blood several times a day. Without food, they die in one to two days.

Detecting the buggers is the trick and not always easy.

Compared to pubic or body lice, the numbers of crawling, creeping adults is relatively sparse. The best areas to look for them are sides and back of scalp. Magnifiers help. Wetting hair might make them more visible. There are really fine-toothed nit combs to use.

Start at the base the hairs and slowly pull out. The nits with embryos tend to be closer to scalp, empty egg shells farther out. Flakes of dandruff or chunks from hair products are easily confused with nits. The big difference is, when you pull your finger along the hair shaft, nits won’t come off, the other stuff will. That is one reliable sign I’ve found over the years. Finding a live louse is finding the gold medallion for diagnosis. In any self-respecting dermatology office, there is almost always a microscope. You can snip the hair off look for the embryo in the egg. If gone, the lid or operculum is open and shell empty.

There are scads of businesses that will examine heads for $20-30 a preening. You have to decide how much that peace of mind is worth. Prevention is common sense in eliminating contact from head to head or sharing clothing, combs, etc. No monumental efforts are needed. Really. Treatments can be over the counter or at your smiling dermatologist’s office. Some concoctions treat only live lice, and some treat both lice and nits. Resistance to certain chemicals has built up in a few louse populations as well.

That’s the nitty gritty of lice detection. Some very phobic folks indulge almost obsessively in nit-picking, or picking the eggs off, one by one. The businesses created over this kind of activity are incredible and bordering on predatory.

I hope this gives you a head’s-up to find head lice if you think they’re there. When I was derm resident in the 1970s, one of our sons had scalp itching. His mother asked me if he had lice. I looked and said nope. Our son then saw the young, new staff dermatologist there, who did find them. I learned a lot.