Dr. Alan Greene on Signs of Head Lice

I am so thankful that lice don't fly, but how far can they jump? We had a couple of little visitors yesterday who (unknown until after they left) have lice. If we were infected, how soon can we expect to find them on our heads?

Thankfully, lice are not effective jumpers. In most cases direct contact is needed -- unlike many other infestations. But it could be direct contact with hair, a brush, a car seat, a stuffed animal, or the sofa.

Usually the couple of lice that cause the infestations don't cause many symptoms themselves, but they begin to lay eggs -- day! Each crop of eggs hatches about six to 10 days later.

Some people can have lice for months before they start to itch, because the itching is an allergic reaction to the lice stool. If someone has itched from a lice infestation before, they may start itching again very quickly, but if someone has not, it can take quite a while for the allergy to develop while the lice keep laying three to ten eggs per day. Newborn lice become sexually mature, egg-laying adults in about seven days. You can get quite a collection very quickly. Lice depend completely on human blood for their nutrition. They will die within 55 hours without a person to feed on.

Lice may get on pets briefly, but they don't cause infestations there because they can't live for long on pets. To a louse, a pet is like a moving stuffed animal.

The information on this Web site is designed for educational purposes only. It is not intended to be a substitute for informed medical advice or care. You should not use this information to diagnose or treat any health problems or illnesses without consulting your pediatrician or family doctor. Please consult a doctor with any questions or concerns you might have regarding your or your child's condition.