Lice (singular: louse), also known as fly babies, (order Phthiraptera) are an order of over 3,000 species of wingless phthiraptra. They are obligate ectoparasites of every mammalian and avian order, with the notable exceptions of Monotremata (the duck-billed platypus and the echidna or spiny anteater) and Chiroptera (bats).
A louse egg is commonly called a nit. Lice attach their eggs to their host’s hair with specialized saliva which results in a bond that is very difficult to separate without specialized products. A nit comb is a comb with very fine close teeth that is used to scrape nits off the hair.
The order has traditionally been divided into two suborders; the sucking lice (Anoplura) and chewing lice (Mallophaga), however, recent classifications suggest that the Mallophaga are paraphyletic and four suborders are now recognised:
Anoplura: sucking lice, including head and pubic lice (see also Pediculosis or Head lice)
Rhyncophthirina: parasites of elephants and warthogs
Ischnocera: avian lice
Amblycera: chewing lice, a primitive order of lice
Lice are highly specialized based on the host species and many species specifically only feed on certain areas of their host’s body. As lice spend their whole life on the host they have developed adaptations which enable them to maintain a close contact with the host. These adaptations are reflected in their size (0.5 mm to 8 mm), stout legs, and claws which are adapted to cling tightly to hair, fur and feathers, wingless and dorsoventrally flattened.
Lice feed on skin (epidermal) debris, feather parts, sebaceous secretions and blood. A louse’s color varies from pale beige to dark grey; however, if feeding on blood, it may become considerably darker.
The picture depicts the chewing louse Damalinia limbata found on Angora goats. The male louse (right) is typically smaller than the female (left), whose posterior margin of the abdomen is more rounded than those of male lice.
Lice are a highly contagious disease of humans. Lice have been traced back in time over thousands of years. An infestation of lice is referred to as Pediculosis. There are three species of lice, they all live off of human blood, and are not found on cats, dogs, birds, or other animals. The Head Lice (Pediculus humanus capitis) is the most common form. The Body Lice (Pediculus humanus humanus) occurs less frequently, and the third type of louse, Pubic Lice (Pthirus pubis), commonly known as Crabs, are generally considered to be a sexually transmitted disease.
Lice infestations are common, found worldwide, and affects between 6-20 million people every year. Lice do not discriminate based on wealth or cleanliness. They affect all races, however, they are more prevalent in Caucasians in the United States due to the round shape of the hair shaft.
Other contributing factors are age, family size, clothing care, personal hygiene, and overcrowded conditions.
Head lice live from three weeks to six weeks, depending on temperature and humidity. During their lifetime, a female can lay up to 100 eggs at a rate of about 6-7 a day. Of those eggs, only the ones that have been fertilized will hatch. Lice must feed on human blood every day in order to survive. Once they are dislodged from there host, they will die within 45 minutes. The nits can survive for 4-10 days off of a host, but once hatched they must feed on a human host within 24 hours, or they will die.
Body Lice live on the body and in the clothing or bedding of infested humans. Body lice infestations spread rapidly under crowded conditions where hygiene is poor and there is frequent contact among people. Infestation is unlikely to persist on anyone who bathes regularly and who regularly has access to freshly laundered clothing and bedding.
Pubic Lice (Crabs) can live in almost any form of human hair, but is found most commonly in pubic hair. Its legs are adapted to climbing along relatively widely spaced hairs, and so it can be found in eyebrows, pubic hair, beards, moustaches, and even underarm hair. Pubic lice are usually spread through sexual contact. Rarely, infestation can be spread through contact with an infested person’s bed linens, towels, or clothes.
Lice are transmitted from person to person by close personal and prolonged skin contact, including sexual contact. It can be common in families, dormitories, nursing homes, hospitals, schools and other institutions. It is also possible to acquire a lice infestation via inanimate objects, such as contaminated items of clothing, hats, bedding, towels, combs and brushes, coats, scarves, and upholstered furniture.
Treatment of human head lice:
There are various methods for treating head lice, developed since ancient Egyptian times when lice first became a problem for humans.
Shaving the Head
Shaving off all the hair is a viable solution.This can be performed alone using mirrors to see all sides of the head, although it is easier to have someone else help with the procedure. A completely shaven head is necessary, a mere buzz cut is not sufficient.
Shaving the head gives the lice little to grasp to stay attached to the head. In addition to head hair, lice may infest facial hair or eyebrows, and these may also need to be removed for effective treatment.
While effective, some patients may find the hair removal aesthetically unappealing.
Human head lice can be killed by a 1% permethrin or pyrethrin (neurotoxic) or Lindane lice shampoo. As the lice live very close to the scalp, there is no need to coat the entire length of the hair. The hair must be combed with a fine-toothed comb after treatment to remove the nits.
Chemical solutions generally require at least three weeks of treatment.
Combing, also called nitpicking, is a particularly effective method for removal of lice without the use of any medicine, special shampoos, or meticulous visual inspections.
A special comb can remove nymphs and adult lice, but not their eggs. Black combs are frequently used to ease visual inspection, but metal combs may be used as well. Plastic combs may become ineffective due to the separation of the teeth after use. Combing takes approximately 10 days to clear the head of lice.
In addition to removal of lice from the hair, it is common to clean items such as bedding and clothing which the lice may also have infested. The items can be cleaned in hot water. Head lice do not survive in bedding and clothing for more than 24 hours.
Resistance to commercially available anti-lice shampoos such as the above is becoming increasingly common. Pesticides like these can be dangerous to humans, and raising pesticide levels can be problematic due to concerns about the current level being toxic. Some studies suggest an elevated risk of childhood acute leukaemia following exposure.
Natural solutions permeate the Internet and are also sold in some retail stores. Their effectiveness is not always supported by research studies.
Neem seed extracts
Shampoos based on Neem seed extracts can also be efficient if used properly.
One alternative to insecticidal treatments, particularly where resistance is common, is to use an electric comb such as the RobiComb. Alternating teeth carry a high voltage (though the developable current is small, and so the device is safe). Fine combing causes any contact with the lice to result in their electrocution. This allows diligent combing to eradicate an infestation.
Essential oil shampoos
Another procedure is to shampoo the hair with pure essential oils of two parts tea tree and 1 part peppermint oil. The process is repeated once every two days over a period of eight days.
Bugbusting, involves combing wet hair covered with ordinary hair conditioner using special combs: the conditioner immobilises the lice so they can be detected easily. Used properly, this method appears to be as effective in practice as poison; lice cannot develop resistance to it, and it is economical and safe. But the process is tedious, particularly on curly hair, and must be repeated diligently four times over a two week period to cover the full life cycle of the lice.
Humans’ first natural line of defense against head lice is their own natural hair oil. The oil interferes with the louse’s ability to cling to hair shafts and lay eggs (which are attached around the hair shaft). Clean hair is therefore more vulnerable to human head lice.
Ponytails and tight braids tend to reduce the likelihood of acquiring a head lice infestation among those with long hair. Head lice crawl slowly; they cannot fly or leap. Therefore proximity to people who may be infested is not risky, but one must avoid sharing hats, hooded jackets, and hair decorations.
Lice also have a genetic preference to the shape of hair common in their region of origin; African head lice thrive better with oval hair, North American head lice with round hair.
Homeopathic Gel may sometimes work well.
Head lice Home Remedy— effective natural remedy .
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.
www.dermatechrx.com/lice and en.wikipedia.org