Head lice, or pediculosus humanus capitis as it is called in Latin, are a very common infestation in the US, especially in children. It is estimated that between six and twenty million people are affected with head lice each year. These particular parasites are uniquely suited to living on the human hair. They have 6 individual legs, with claw like pinchers that are designed to grasp the hair shaft.
Most cases of head lice in the US affect Caucasian ethnic groups, and many scientists theorize that this is because the shape of the hair shaft is round, as opposed to African-Americans, who have a more oval shaped hair shaft. There is a species of lice that affect those of African descent; however they are not prevalent in the US, only in Africa.
Head lice feed off of human blood, and must feed 4 to 6 times per day. They are completely dependent on a human host for survival; making getting rid of them all the more important. They survive by feeding; biting the scalp and then injecting saliva into the wound. This keeps the blood from clotting and allows the lice time to ingest the blood meal. At the same time they may leave dark red feces on the scalp. Head Lice have a life cycle of about one month, if left unattended. In the life span of a female louse, she can lay well over one hundred eggs.
Head lice mature through a few different cycles during their month long life span. They begin life as nits. Nits are head lice eggs, they are attached to the hair shaft with a waxy, glue like substance, secreted by the female louse upon laying the egg. The nits are covered completely with this glue substance except for the operculum, which is the cap that the embryo breathes through.
Head Lice nits appear brown until they hatch. When they hatch the nymph will leave behind the egg shell which will appear white. Head Lice nits will hatch in six to nine days, but this is largely dependent on the environment that they are in.
After they hatch, they are called nymphs. Nymphs will molt three times before they become adult lice. Nymphs cannot fly, however there have been reports that, nymphs have been blown out of the host’s hair in early stages of life. The amount of time it takes for nymphs to mature is approximately eight to nine days.
Contrary to popular belief, head lice cannot jump or fly. They are transferred from one host to another by direct contact, or are transferred by sharing hair brushes, hats and occasionally they can be spread by clothing or upholstery, however contact must be relatively soon after the infected person has had contact with the surface since human head lice can’t go more than an hour or two without a human host for food and warmth.
Another misconception about head lice is that it only affects those with long hair. This isn’t true, head lice can affect anyone, no matter how long their hair and while it may be easier to remove lice from short hair, short hair will not prevent a head lice infestation.
Infestations are more common in places such as day care centers, hospitals, dorms, and nursing homes due to the communal nature of these facilities. It is also more common for girls to be affected than boys, likely due to the fact that girls play with each other’s hair while playing dress up or having sleep-overs. Also those who have extremely clean hair and scalp are at a higher risk as it is easier for the lice to attach their eggs, called nits, to the hair shaft.
It is also a misconception that humans can contract head lice from their pets. This isn’t true, nor can humans pass head lice onto their pets. So Fido is perfectly safe and there is no need to shave the cat.
There is a growing debate about whether or not humans can contract diseases from head lice. Most doctors will say no, however some say that since humans can contract typhus and other diseases from body lice, that it is also possible that they can contract diseases from head lice. More research is needed to reach a conclusive answer. Whatever the answer is, head lice usually itches enough to encourage prompt treatment anyway.
Diagnosing Head Lice
Diagnosing head lice is relatively simple. Lice and there nits (eggs) can be seen with the naked eye. Many school programs perform random screening and screen other children in a class where a student has developed a head lice infestation, simply by parting the hair in a few places to look for lice and nits.
Another simple, although occasionally more uncomfortable, method for determining if a head lice infestation is present is to comb through the hair with a nit comb. Nit combs are combs that have teeth that are very close together, usually .01 inches between teeth. Metal teeth combs are much more effective than the nit combs with plastic teeth, as the ones with plastic teeth tend to bend and stretch out over time.
If using the nit comb method, one would comb through the hair from scalp to end, and then observe if there are any live lice or nits on the comb. This can be uncomfortable for people with long, curly or thick hair, as it is very difficult to pass the comb through the hair. It is also common to observe lice bites on the scalp and neck in those with a head lice infestation.
Treating Head Lice
Traditional head lice treatments can be an arduous task. Often the hair and scalp will have to be treated several times to completely remove the lice. There are several de-lousing products on the market and there are a number of natural ways to treat head lice as well. We’ll discuss each method in detail in a moment.
Common misconceptions about treating head lice include the idea that shaving one’s head is an effective treatment. In fact it isn’t, since head lice can affect people no matter what the length of their hair, and in fact may cause psychological damage to small children who have to endure having all theirs shorn off. This can be a traumatic event to children, so unless you have a child who is used to having short hair anyway, it won’t do any good to cut their hair off, except to give you less hair to de-louse.
Most products on the market that remove head lice are combination systems. You can usually buy the products separately but it’s faster and easier to get the kits. Traditional toxic head lice products contain some type of insecticide, either permethrin or Piperonyl butoxide and Pyrethrum extract. The kits contain medicated shampoo or conditioner, metal teeth nit combs and a treatment spray to treat things like sheets and bedding.
While these products are effective, it can take several treatments to completely get rid of an infestation. They also contain harsh chemicals, and some people may be sensitive to these chemicals. The other problem with these products is that nits and head lice become resistant to the insecticides. For those instances, other methods would be more effective.
For those who don’t want to use the more traditional over the counter remedies, there are some more natural ways to get rid of head lice. They may also be more labor intensive. One such example is what is termed as “nit picking”. It is basically the manual removal of lice and their eggs. While there are no chemical treatments involved, it is extremely tedious and time consuming and it is possible to miss head lice and nits.
Another promising way to get rid of head lice is the use of silicone based lotions; however is very toxic. Dimethicone is a silicone based lotion or ointment that is effective at removing head lice by smothering or dehydrating them. You would apply the lotion to the hair and scalp and allow it to completely dry. You would then leave it on for at least eight hours.
Head lice who cannot feed frequently will die, so eight hours should be sufficient to get rid of most of the living head lice. It is not effective in removing nits however, so repeating treatment will be required once a week until the infestation is gone.
There are a couple of combination products that have an immediate effect on nits. They combine dimethicone to fight against the live head lice and penetrating excipients that increase the effectiveness, to the abdominal spiracles, through which head lice breathe and the operculum, through which the nits breathe while in the egg.
Usually the products that are effective at eliminating adult head live aren’t effective on the nits since they are protected by the egg shell; there is only the one opening in the cap. Adult head lice are much more vulnerable, since they breathe through multiple openings and they aren’t protected by an egg shell, but an exoskeleton, which can be compromised by de-lousing chemicals and enzymes.
Preventing Head Lice
The only way to prevent head lice is to avoid direct contact with someone who has it. This means no sharing of brushes, hats, hair accessories, clothing, bedding or any other soft surface that lice can live on for a short period of time without a host.
Myths about Head Lice and it’s Treatment
Head lice can affect anyone regardless of their social class, ethnicity or cleanliness habits. In fact, research has shown that hair that is “too clean” provide an even more ideal environment for head lice to thrive. Infestation with head lice is not a disease or something to be ashamed of. Medical impacts from head lice are generally minimal, however the psychological damage can be greater, especially when children are singled out or, for the little girl with long hair, made to cut all her hair off.
There are several “old wives tales” about treating head lice that simply aren’t effective and may cause more damage. Washing hair with things like kerosene, hair dye or bleach, household bug sprays, or products meant for animals are not effective for eliminating head lice and could end up just causing more irritation.