LifeCycle of Head Lice
Liceare a fairly common problem for children especially, as well as forpeople who come into contact with children often. These tinycreatures live on human scalps and survive by drawing blood viaextremely small holes that they make in the scalp. During an outbreakof lice, it is not uncommon to see different lice in various stagesof the life cycle on one scalp. Therefore, understanding thedifferent stages of life a louse undergoes is essential in knowingwhen and how to treat them.
Liceon a host usually take between 3 and 4 weeks to develop from an eggto an adult. Each female louse can lay anywhere between 50 and 150eggs (also known as nits) during her life; the recently laid eggs aredistinguishable by the opacity of their shells, while the recentlyhatched eggs are more transparent. The eggs can be tricky to removefrom the scalp due to the fact that they are typically rooted inplace by a sticky material called chitin, although vinegar can beused to weaken the chitin enough to remove the eggs easily.
Oncehatched, the young lice nymphs have a grey-brown colouration and willgrow and shed their skin three times, after which they are fullymature adults that can and will procreate. Younger lice are smallerand more difficult to see due to their colouration, but become muchmore noticeable as they grow. Adult lice typically live for four tosix weeks while on a human host.
Headlice require nourishment from their hosts many times each day andcannot do without their host. Once removed from the human scalp, licedo not survive for long, the eggs lasting for up to two weeks and theadults lasting for only a few days. Lice cannot continue with theirlife cycle once removed from the host, so catching them early isadvised.
Thefirst symptoms to watch out for are itching of the scalp and possibleswelling of the lymph nodes in the neck. The lice can usually beclearly spotted upon closer examination of the scalp. Liceinfestations spread through contact, so one person's hair touchinganother's hair who has lice may spread the infestation. Also, usingvarious things that have touched an infested scalp, such as hairbrushes or combs and hats, can also transmit the infestation bytransferring some eggs.
Typicaltreatments include manual removal of the eggs and lice and washingthe scalp with 'pediculicides' that kill the matured lice but usuallynot the eggs. Thus a second round of washing the scalp should occurat least a week later to ensure that any eggs will have hatched andthe nymphs can be killed successfully. Remember, these pediculicidesare slightly toxic, so care must be taken when using them.