Back-to-school time means head lice time—it is the peak season for the parasites to be passed around. Lice are wingless, parasitic insects that settle wherever there is hair. Lice are contagious, but they can only move by crawling. That means they are passed from person to person by direct contact; kids frequently spread lice by sharing hats, combs, or hairbrushes. The good news is that, while itchy and sometimes unsightly, head lice are frustrating but harmless.
Head lice are the second most common communicable disease among schoolchildren in the United States—only the common cold is seen more often. That means that having a child with lice is not a moral failing, or a sign of being unhygienic, or of neglect; it simply means that the child has lice. The are so easy to pass, and the eggs, called nits, are so small and hard to see, that lice are actually quite common.
In fact, the ease with which lice are transmitted can tell researchers important things about human history, even from before writing was invented. Head lice and body lice are actually the same creature, simply settling in wherever it can comfortable nestle, and they were ubiquitous among prehistoric humans. Scientists have been able to use the genetic markers in lice to trace their ancestry, the way DNA testing can be used to trace human family trees. With lice, this makes it possible to follow the migration patterns of humans as they came out of Africa, across Eurasia, and into the Americas, simply by tracking their parasites.
Getting rid of lice is easiest when they are nits. Thorough and regular combing, and searching the hair for signs of infestation—the nits are yellow or tan dots, the lice themselves tan creatures about the size of a sesame seed—will usually take care of them for good.
If that fails, more drastic measures may be called for. However, one of the most powerful weapons against head lice in the tonsorial arsenal is ordinary conditioner. In a study, standard conditioner was found to be no better than hair products specifically marketed as effective against lice in getting the nits off hairs. For hatched lice, almond oil will stun them and loosen their grip on the scalp, making them more vulnerable to being combed out.