What are head lice?

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 times a day and live close to the human scalp. Head lice only affect humans and cannot be passed on to animals.

How do you catch head lice?

Head lice are most common among primary school aged children. They cannot fly, jump or swim and are spread by direct contact with the hair of the infested individual. A head lice infestation is not the result of dirty hair or poor hygiene and it can affect all types of hair regardless of its condition or length. Head lice are rarely transferred through clothing, hats, furniture or bedding.

Female head lice lay eggs close to the scalp on the hair shaft. Eggs hatch after 5-7 days, leaving empty eggshells (nits) glued to the hair shaft. These eggshells are more noticeable as hair grows and they get carried away from the scalp. Nymphs that emerge from eggshells take 7-8 days to grow to adult sized lice. They may take another 7 days to start breeding and hence it is important to remove them to stop them spreading.

Do head lice cause illness or disease?

Head lice do not transmit disease causing micro-organisms. However, they can cause irritation, resulting in itchiness. Sometimes, itchiness and subsequent scratching of the scalp can increase the risk of secondary infection.

Using insecticides and other substances to control head lice can actually have more serious health effects than the lice themselves. Swapping between different treatments or using several different treatments at the same time can cause serious skin irritation, itchiness and other complications. Registered chemicals that kill lice are usually safe, but excessive use of other substances, such as home remedies and other insecticides, can cause irritation.

How serious is the head lice problem?

Head lice are one of the most commonly reported health complaints from parents and teachers. The NSW Health Nitbuster program has found that when sampled, more than 23 per cent of primary school aged children in New South Wales had head lice. Infestations appear to be on the increase, due to factors such as:

  • resistance to the common chemicals used in head lice products
  • inappropriate use of the treatments
  • changing social and school practices.

While head lice are not known to carry disease, they are a nuisance for parents and children. The social stigma associated with head lice infestation can affect children's comfort and ability to learn in the classroom. Unsuccessful treatments can frustrate parents and lead them to seek more desperate measures that may be harmful and ineffective.

The Nitbusters Program addresses treatment issues and teaches participants how to handle the problem in a community setting.

Resources for parents and their kids

Current as at: Monday 8 March 2021
Contact page owner: Environmental Health