How does a head lice infestation start?

Lice are tiny insects that cause infestations when they make their way onto the scalp via combs, brushes, hats or any other object that touches the head of an infected individual, according to Healthline. Adult lice lay eggs that hatch on the scalp and multiply rapidly.

Symptoms of a head lice infestation include itching, lice eggs around the hair shafts and live lice on the scalp, according to Mayo Clinic. Itching occurs when the saliva of the insects comes in contact with the skin on the scalp and causes a reaction. Lice eggs, also referred to as nits, are not always visible with the naked eye, as the eggs are minuscule and can easily blend in with human hair.