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Head Lice (Pediculus humanus capitis): Causes, Treatment and Prevention. Definition Head lice (Pediculus capitis) are small, wingless, egg laying insects found on the human head. They grow to about 3.5mm (the size of a sesame seed or pin head). Head lice live on the hair and feed by sucking blood from the scalp. They are pale grey in colour before feeding and reddish brown after feeding. Louse and it’s eggs on the hair Live eggs (sometimes called nits) are glued to the hair shaft within a distance of 1.5 cm from the scalp. They hatch in 7-10 days as young lice (nymphs). It takes up to ten days for the nymphs to become mature lice and begin laying eggs. Adults are larger than nymphs and a mature female lays up to eight eggs per day. Head lice: Cannot jump, fly or swim Do not carry disease Stay on the scalp after swimming or bathing/showering. What do head lice and their eggs Look Like? The insects are tiny, wingless, move quickly, and are difficult to see. They cannot jump or fly. They are 1 – 2 mm long and greyish brown in color. There are three forms of Lice: the nit, the nymph and the adult. Forms of head lice Nits: Nits are head Lice eggs. They are hard to see and are often confused with dandruff or hair spray droplets. Nits are found firmly attached to the hair shaft. They are oval and usually yellow to white. Nits take about one week to hatch. Nymph: The nit hatches into a baby louse called a nymph. It looks like an adult head lo use, but is smaller. Nymphs mature into adults about seven days after hatching. To live, the nymph must feed on blood. Adults: The adult lo use is about the size of a sesame seed, has six legs, and is tan to greyish-white. Females lay nits; they are usually larger than males. Adult lice can live up to 30 days on a person’s head. To live, adult lice need to feed on blood. If a louse falls off a person, it dies within two days. Life cycle of head louse They lay their eggs (nits) on the hair shaft around 1.5cm from the scalp. Each louse can live for approximately five weeks, but during that lifetime a female can lay up to 120 eggs. This life cycle lasts between 33 and 35 days. Life cycle of head lice The life cycle of head lice begins with eggs being laid, hatching, maturation into adults, mating and egg laying after which the parent head lice die. These eggs will hatch in six to ten days continuing the life cycle until the infestation is treated and the cycle is broken. The typical louse dehydrates and dies anywhere between 6 and 24 hours when away from the scalp. Historical view behind heal louse It is generally thought that human head lice evolved from head lice on chimpanzees over 5.5 million years ago. In about 107,000 BC, it has been recorded that lice split into two groups; head lice and body lice. It seem to follow the historical trajectory of humans; about 120,000 years ago, there was a significant contraction in the population of humans as humans migrated from Africa. The timeline of head lice discoveries continues with additional nits uncovered on an Egyptian mummy in 3,000 BC. The mummy was dated to 5,000 BC. Interestingly, lice combs were found in the tomb, showing us that while many things have changed, the method of choice for eliminating head lice, combing, remains unchanged. The ancient nit combs that were discovered Egypt look very similar to the combs of modern day. It has been said that Cleopatra had very elaborate nit combs; as we see today, lice knew no class barriers. As time continued, lice were discovered in lice combs that were dug up from archaeological sites in Israel and dated from about 1st Century BC to 8th Century AD. In the first century AD, a comb with a louse attached was excavated from a site in Cumbria, England. Additionally, a nit was discovered on a hair shaft of a female whose body was preserved in the lava of the Mt. Vesuvius volcanic eruption in 79 AD. It is thought that Rome had quite a prevalence of head lice at that time. The first major discovery of head lice in the western hemisphere was in around 1100 AD on the hair of a mummy from Peru. The first record of head lice in the U.S. is from early 1800’s in Wisconsin. The bottom line with lice is that they have been around a long time and appear here to stay. They are very hearty. When threatened, they mutate. Today we see strains of head lice that are dubbed “super lice” due to resistance that they have developed to chemical pesticide shampoos. After many thousands of years, what remains for humans is to accept that lice are here, they need our head and blood to survive, and that to eradicate a case, we need to comb and pick each nit and bug from the hair. Epidemiology Pediculosis capitis (head lice infestation) is probably the most common parasitic condition among children worldwide. It is particularly common in resource-poor communities in the developing world, where it affects individuals of all age groups, and prevalence in the general population can be as high as 40%. Children aged < 12 years show the highest prevalence and bear the highest burden of disease. How do you get head Lice? By close head-to-head contact with someone who already has head lice. Contact is common during play at school and at home (slumber parties, sports activities, at camp, on a playground, etc.). By using hats, scarves, combs, brushes, hair ribbons, pillows or towels recently used by someone with head lice. Transmission of lice It can neither jump nor fly, but crawl from head to head in situations where there is close contact. The likelihood of spreading lice via pillows, furniture, cuddly toys and clothes is extremely small. Nevertheless, borrowing headwear, brushes, combs, hair accessories and other items from someone who has lice is not recommended. Cases of lice are seldom isolated. Without treatment, families and close friends may infect each other repeatedly What are the symptoms of head louse? Often people who have head lice will have no symptoms for 4 to 6 weeks with their first case. Symptoms of head lice may include: Crawling or tickling sensation on the scalp; Itchy scalp due to an sensitive reaction caused by the louse’s saliva and feces. Scratch marks or small red bumps like a rash. Scratching can give rise to secondary bacterial infections on the scalp. Swelling of lymph nodes (adenopathy) in the neck can occur in some people due to this infection. Feeling of something moving in the hair, irritability, and sores on the head caused by scratching The presence of eggs is not a reliable sign of active head lice. Eggs need the warmth and moisture of the scalp to hatch. How to diagnose the lice? Combing the hair by a parent or family member is a good way to look for lice. Wash hair well with ordinary shampoo and leave damp. Wet hair slows down the lice, making them easier to remove. Soaking the hair with oil or conditioner from the scalp to the ends may make combing easier. In good light, comb the hair with a wide-toothed ordinary comb to straighten and de-tangle the hair. Switch to a fine-toothed lice comb. You can buy these combs at pharmacies and can ask the pharmacist for help in choosing one. Work through the hair in small sections, starting with the skin of the scalp/roots at the top of the head and comb through to the ends of the hair. Check for moving lice with every stroke. Wipe the comb after each stroke with a tissue and place tissues in a bag. If you are not sure if you have found a louse, use clear tape to attach it to a piece of paper. Show this to your health care provider or other person trained to identify live head lice. Repeat steps 3 to 5 until all of the hair on the head has been combed. Tie up the bag with used tissues and throw it in the garbage. If moving lice are seen, wash all of the conditioner or oil out and start treatment. At least once a week, check the scalp for head lice insects and eggs, especially: Around the hairline at the back of the neck Behind the ears On the crown (top of the head) Treating head lice Chemical treatments or wet combing are the usual ways to treat head lice. Talk to your pharmacist, doctor or nurse for advice. Ordinary shampoo or soap will not kill head lice. Do not use fly spray, kerosene or animal treatments, as these may harm children. Chemical treatments Chemical treatments use a special shampoo or lotion (containing insecticide) that kills the head lice and the eggs. Follow the instructions that are supplied with the chemical treatments. Always do a second treatment 7–10 days after the first. This is to kill any head lice that may have hatched after the first treatment. The following types of active ingredients were used against head lice: Pyrethrins, eg. Amcal Head Lice Foam, Lyban Foam Synthetic Pyrethroids (bioallethrin, permethrin), eg. Paralice, Quellada Head Lice Treatment Organophosphates, eg. Exolice Medicated Foam, Lice Rid Combinations of Herbal and Essential Oils, eg. Quit Nits Natural Head Lice Treatment, Herba Lice Wet combing Wet the hair and scalp with conditioner (this makes it easier to see the head lice). Use a fine-toothed comb to check for head lice and eggs and to comb them out. It’s best to use a fine metal comb, or a special head lice comb you can get from a pharmacy. Comb the full length of the hair, from the scalp to the ends. Work your way around the head so that you have combed all of the hair. If you see any head lice or eggs, clean the comb by wiping it on a tissue or a paper towel, or rinse the comb before you use it again. After you have combed all of the hair, rinse out the conditioner. Repeat the wet combing each week until you don’t find any more head lice or eggs. Prevention and control It’s not possible to completely prevent head lice because they’re very common. But there are things you can do to stop head lice from spreading. Brush hair every day. This may help kill or injure head lice and stop them from laying eggs. Don’t share brushes, combs, headbands, ribbons, hairclips, helmets or hats – anything that touches someone’s head. Having short hair – or wearing hair in a ponytail if it’s long – makes it less likely you or your child will catch head lice. Children should hang their clothes on their own hook at school. Children should keep their clothes apart from other children’s in swimming or sport changing rooms. If you do get head lice in your family, everyone that has them should be treated at the same time. Let the school and any other close friends know that your child has been treated for head lice.

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