Lice

You can only get lice from another person with lice

The mere mention of lice makes our heads start itching. As pediatricians, we often see children in our clinics with lice, and it never fails to make us start scratching our own heads when we leave the room. You may remember the days in school when someone in the class had lice, and then everyone in the class had to have their heads examined closely for the foul louse. Rachel had very long hair, which was a nightmare for the thorough lice checkers.

Lice are tiny creepy, crawling bugs that live on the head or the hair of the head. They can be tough to see because they are gray or brown and only an eighth of an inch long. The grown-up lice lay eggs that are called nits. These nits or eggs may look like loose white dandruff or flakes in someone’s hair, but they are actually stuck very tightly to the strands of hair and do not wash off easily. Lice are baby-making machines. A female louse lives for only thirty days, but she can lay more than 2,600 eggs! Female lice can actually store sperm inside themselves, so mating just once allows them to lay fertilized eggs for their entire lives.

Lice can definitely spread through direct contact with someone else who has head lice. If your head touches the head of a person with lice, their lice can happily—for them—move onto your head and set up camp in your hair. Head lice do not jump or fly, so for a long time people thought that this kind of direct contact was the only way that lice moved from one person to another. Lice require human beings in order to stay alive, and many people have thought that only the adult lice were strong enough to infect another person.

Unfortunately, you can also get lice even if you do not come into direct contact with an infected person’s head. You can get lice from sharing a comb, hat, headband, or any other hair accessory with someone who has lice. You can get lice from baseball caps, earphones, pillowcases, and upholstered furniture. Both teenaged lice (called nymphs) and adult lice can live for up to three days when they are not on human beings. The eggs can survive and still hatch into more lice for ten days. (Rachel is scratching her head just contemplating these numbers.) Scientists have tested whether lice can transfer from a scenario where a single strand of hair touches a louse that is on a suspended thread of the sort that you would have on an upholstered chair or a pillowcase. The louse can do it! Another study examined whether lice could be transferred from pillowcases. This study found that, while some lice did move onto the pillowcase at night, only a small number did so. It is possible for the lice to get on the pillowcase and subsequently infect a new person, but it is a much less common way to get infected than being in close contact with someone’s head or comb. Even though the risk of being infected from a pillowcase is low, the number of lice that did transfer onto the pillowcases pointed to the need to change pillowcases so you are not reinfected with lice and so that other people are not infected. Lice can be killed from pillowcases by immersing the pillowcase in hot water, by washing in hot water, or by fifteen minutes in a hot clothes dryer.

Lice also have a natural instinct to move quickly away from the light or to move when the hairs in which they are living are disturbed. This makes them very quick at finding new places where they can live, even if that new place is farther away from their original head of hair. Studies of lice movement also find lice crawling on the pillows of people with lice or on the towels of people with lice who have just shampooed, washed, and dried their hair. Combing the hair of someone with lice with a normal comb leaves lice on the comb, on the ground, and on the clothing of the person who does the combing. Hair blow-dryers can also send lice flying into the air, where they can land on other people or on fabrics where they wait around for new people to infect. You can vacuum lice up with a regular vacuum cleaner, but hand vacuums do not pick up all the lice and nits, which can then cause more infestations. Because of how lice spread and flee onto whatever surface they can, most school nurses (who often deal with a lot of lice issues) recommend vacuuming the floors and furniture that have been in contact with someone with lice.

Because lice are so incredibly infectious, it can be really hard to get rid of them, especially once someone in your house has them. Getting lice does not mean that you are dirty or living in bad conditions; it just means that these wily little buggers made a successful attack on your head. To get rid of lice, your best bet is to use a special shampoo designed to kill lice, and then to comb the hair with a special comb designed to help get rid of the sticky nits attached to the hairs. You should consult your doctor about which medicated shampoo to use, especially since some are not safe for young children or pregnant women. In addition to the rounds of shampooing and combing, a lot of cleaning has to go on! Because lice and their eggs can survive on things like pillowcases and hats, you should launder everything that the infected person might have come in contact with. This means washing their bedsheets and towels, and vacuuming all the floors, carpets, and upholstery in the house.