Health News Digest

October 30, 2006

‘Tis The Season…For Head Lice

Head louse

By  Michael D. Shaw

Along with the glorious colors of the leaves turning in much of the country, and cooler temperatures, the arrival of autumn can often bring more. I’m referring to head-scratching among school children, and that doesn’t just mean that they might be asked a question by their teacher that seems to be difficult to answer.

The head-scratching may be caused by that common parasite—Pediculus humanus capitis—also known as the head louse. And, since no human host gets just one, they are better known by their plural form—head lice.

Since head lice can be spread whenever there is direct contact of the head or hair with an infested individual, and via the sharing of personal articles such as hats, towels, brushes, and hair ties, it is not surprising that schools would be a fine place to catch these pests. These creatures do not have hind legs that would allow them to jump like fleas, and they don’t have wings to fly, so they cannot of their own volition spread from one host to another.

The good news is that lice are non-discriminatory; they make no distinction between race, class, or religion, despite the false beliefs of some who cling to the idea that any outbreak is solely a phenomenon of the poor or slovenly. The bad news is that, given our abuse of various medicines, lice now have an immunity to traditionally powerful forms of treatment. In fact, scientists believe that 80 percent of these insects can fight most over-the-counter lotions, including the chemicals permathrin and phenothrin. Treatment is only an option when active lice or viable eggs are visible. Itching of the scalp or the perception that something is crawling on the head do not warrant treatment for lice.

Bear in mind that head lice are an annoyance, not a public health crisis. They rarely cause direct harm, and are not known to transmit infectious agents from person-to-person. However, since the head lice is closely related to Pediculus humanus humanus, the body louse, which does transmit such diseases as typhus, it is wise not to ignore the pathogenic possibilities of head lice.

Head lice can cause itching or loss of sleep; the louse’s saliva and feces may sensitize people to their bites, worsening the irritation and increasing the chance of secondary infection from excessive scratching. Another factor, only recently being publicized, derives from the well-intentioned but misguided use of caustic or toxic substances to eliminate the lice.

Some products are available that are touted as being “natural,” even if there is no accepted definition of this term. Of course, a less toxic treatment is preferable, but little data is available establishing efficacy. Indeed, efficacy of treatment will always be clouded by the determination and diligence of the parent, above and beyond the inherent factors of the treatment modality.

The most effective treatment, and the least toxic, is the time-proven method of using a specialized comb to remove the lice, and their eggs (called “nits”). Check the website of the National Pediculosis Association ® for detailed information.

Thankfully, lice generally lack the potential to cause an epidemic. According to the Harvard School of Public Health, the basic reproduction number (a measure that defines the number of secondary infections arising from an index case) is far lower for head lice than for infections due to cold or flu viruses. This opens up the topic of the so-called no-nits policies that are in place in many school districts.

On the one hand, if a child is barred from school for having nits, the condition can be easily cleared up within a day or two. On the other hand, some authorities drift toward political correctness by condemning such policies only because they SEEM to hearken back to lice-related ethnic prejudices of the past. Moreover, they claim that such policies are ineffective, conveniently ignoring the extreme difficulty in obtaining meaningful data on human diseases, especially those whereby treatment efficacy is almost completely dependent on parent effort. Clearly, if there are no nits in the school, there will be no cases of head lice!

Finally, I can’t help but think that those against no-nits may harbor their own prejudices about putting public health into the hands of the public, and not esteemed authorities such as themselves.

Lice are a nuisance, not a cause for panic, unless toxic remedies are brought to bear. Given enhanced means of communication, and the public’s continuing interest in good health, we should be able to vastly reduce the incidence of this parasite.