The head louse, or Pediculus humanus capitis, is a parasitic insect that can be found on the head, eyebrows, and eyelashes of people. Head lice feed on human blood several time a day and live close to the human scalp. Humans are the known host for head lice; dogs, cats, and other domestic pets do not carry lice. Symptoms include a tickling feeling or a sensation of something moving in the hair, irritability and sleeplessness, and sores on the head caused by scratching. It is treatable with commercial brand pesticides that are safe for humans to use. Head lice are not known to spread disease.
Head lice outbreaks are common among children in day cares, schools, and institutions. Based on evidence-based research, classroom or school-wide screening for decreasing the incidence of head lice is not efficient nor cost-effective. The Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) determined that “No-nits” policies that require a child to be free of nits before they can return to school are not recommended. Head lice are a nuisance, but they have not been shown to spread disease.