Head Lice The Head Louse has been a pest to human society for many thousands of years, and one of the reasons why it is difficult to control the spread of this small insect, is due to a general lack of understanding of the louse and its habits. This booklet has been compiled to dispel the numerous myths that surround head lice infestations.
1. WHO GETS HEAD LICE? Let us lay one myth to rest immediately an infestation of head lice is not a reflection of poor hygiene. Head lice make no distinction between clean or dirty hair or between social classes. In fact anyone can get them, and many people do. It is true that females and especially children are more prone to catching head lice, but this is due more to social behaviour, such as hugging and the physical contact that occurs during play, than to any physical characteristic. Close head to head contact of any sort, makes it easy for the head louse to move from one individual to another. 2. WHAT IS A HEAD LOUSE? A head louse is a tiny insect that makes its home mainly on the head of humans. Because it is totally dependent on the human host for its survival, it is called a parasite, and because it lives on the outside of the body it is known as an ectoparasite. It is one of only three species of lice that infest man. The others are the body louse and the pubic or crab louse. 3. WHERE DOES THE HEAD LOUSE LIVE? The head louse is normally found on the head, especially around the nape of the neck and behind the ears. It may also infest the eyebrows. It is uniquely adapted for survival in this environment, with appendages that allow the louse to grip on the fine hair found in these regions and to move rapidly between hair shafts. These appendages are not suited to gripping on to hair found on other regions of the body or on to animal hair or clothing fibres. 4. WHAT DOES THE ADULT HEAD LOUSE LOOK LIKE? The louse has six short legs, each which is equipped with a large claw at the end. The adults are between 2mm-3mm in length. The newly hatched louse is transparent and the blood meal can often be seen through the skin. As the louse matures its skin darkens to match that of its host s skin, normally appearing greyish-brown in colour. 5. WHAT DOES THE EGGS STAGE LOOK LIKE AND WHAT IS A NIT The living eggs of the louse are about the size of a grain of granulated sugar. They are plum-looking and shiny, and contrary to what most people believe, the living egg is not white but greyish brown in colour and very hard to see. The white nits that are often seen on the hair of people with head lice, are in fact, only the empty eggs shells of an already hatched louse and not the living eggs. The living eggs are found within half a centimetre of the scalp, whereas the empty egg-shells, commonly referred to as nits,
are detected further from the scalp. The appearance of these conspicuous white eggs shells is of benefit to the head louse as it draws attention away from the living eggs closer to the scalp. 6. HOW DOES THE HEAD LOUSE FEED? The head louse is equipped with specialized mouth parts that enable it to pierce the host s skin, locate a blood vessel and feed on the host s blood. As the louse bites its host, it injects saliva containing an anticoagulant, anaesthetic and digestive enzymes into the wound. The anaesthetic deadens the sensation of the bite so that the host will not feel it and disturb the operation with a scratching finger tip. The anticoagulant prevents the blood from clotting and blocking the mouth parts. 7. HOW DOES THE HEAD LOUSE BREED AND HOW LONG DOES IT LIVE? The female louse lays her eggs very close to the scalp, attaching them to the base of the hair shaft with a very strong adhesive substance. If conditions are right she may lay up to eight eggs per night. These eggs will remain attached to that hair as long as the hair is on the head, which can take up to two years. At the right temperature (between 22 C and 31 C) the eggs will hatch within 7-10days (below this temperature the eggs will not hatch at all). Once hatched, the immature louse (nymph) begins to feed immediately. It grows quite rapidly and after two days it moults for the first time. It moults twice more, at 5 days and again when it is 9 or 10 day old. After the third moult it reaches adulthood and is ready to mate. There are about four females to every male and to ensure viable eggs the female must mate between laying each egg. Under ideal conditions, lice can live for another month as adults and lay up to 200 eggs in their lifetime. The maximum life span of the head louse is about 50 days. 8. WHERE DO HEAD LICE COME FROM? Can you catch them from animals? The types of lice that infest animals are different in a number of important characteristics from human lice. This means that just as the human louse would be unable to survive on an animal so animal louse will not survive on humans. Head lice are definitely not caught from animals. Can you catch them from unclean homes? Head lice cannot survive away from their host as they need to feed at least twice a day and require the body s heat for their eggs to mature. You will not pick up head lice from unclean homes. If head lice don t come from animals and they cannot survive off the host, the only place they can come from is another human being. Head lice have, in fact, been in our communities for thousands of years and there will always be a percentage of population which is infested with head lice at any one time.
9. HOW DO YOU GET HEAD LICE? Head lice can only be caught by close, personal head-to-head contact with someone who already has them. They are therefore contagious, not infectious; they walk from person to person. They do not jump, fly or swim. They cannot be blown from one person to another and a person cannot breed them in isolation. Although it is the nature of the head louse to constantly seek a new host, it can instinctively tell the difference between a human and an inanimate object. It would be suicidal for the louse to leave its current host to move onto anything other than another human being. Consequently, lice found on chair backs, bus seats, hats or bedding are likely to be single, injured or dying and would be incapable of climbing onto another host. Transmission by any other means, apart from head-to-head contact, is therefore very uncommon. 10. HOW WOULD YOU KNOW IF YOU HAVE HEAD LICE? This may seem a silly question, but it has been claimed that the average time a child has head lice before detection is between three and four months. This statement is easier to understand when you are aware of the following facts: It is very difficult to see both the adult louse and the viable eggs unless you are specifically looking for them. As mentioned earlier, both the adult and egg are inconspicuous because of their colour. Also, the adult can move very rapidly away from parting hair and thereby avoid detection. The white nits (empty eggs shells), although more easily seen, are often mistaken for dandruff, and are difficult to detect when individuals groom themselves. The itching head, which is often the first sign that head lice may be present, may not occur for any time up to four months after the first louse has become resident on the head. This is because the irritation that occurs is not as a result of the physical bite bit is due to an allergic response, by the body, to the substances that the louse injects into the wound. It is estimated that the body will only become sensitive to these substances after about 10 000 bites. But where people have had head lice before, the body will react more quickly. For these reasons, the host may be quite oblivious to the presence of these insects for quite some time. This is unfortunate for man but ideal for the louse, as it enables an outbreak to proliferate before the slightest suspicion is raised. 11. HOW THEN DO YOU DETECT HEAD LICE? Searching for head lice, using hands and eyes, is one of the least effective ways of finding them or their viable eggs, for the reasons mentioned above. Possibly the surest way to check for lice on the head is to comb the hair regularly, using a plastic, fine-toothed dust/detection comb. The adult lice become trapped between the teeth of the comb and are hooked out in this way. The hair should be wet and combed methodically, parting it into sections and combing each section separately, from the scalp to the ends. Combing the hair over a sheet of paper will also assist in detection any lice that are removed in this manner.
Another sign to watch for is fine black dust on bedding. This black dust is in fact the waste product of the head louse which is expelled normally at night when the host is still. The moulted skin of the nymphs may also be evident on the bed linen as again this skin shedding process normally takes place at night. These waste products may be rubbed onto bedding and clothing, causing them to become grubby more quickly then usual. Obviously if the scalp is itchy this may also be an indication that head lice are present and a thorough search should be undertaken to determine the cause of the irritation. 12. IF YOU HAVE HEAD LICE FOR A LONG TIME, WILL YOUR HEAD STILL ITCH? It is possible for the body to stop reacting to the bite of the head louse after long or repeated infestations. This means that some people will no longer be alerted to the presence of head lice by their heads becoming itchy. This is sometimes the case with adult carriers. 13. HOW DO YOU TELL THE DIFFERENCE BETWEEN NITS AND DANDRUFF? Dandruff and scalp exudates can be easily removed from the scalp or hair by use of fingernails. Nits however are attached with a very adhesive substance and will be a lot more difficult to remove. Scalp exudates will often surround the hair shaft, whereas nits will be attached to the side of the hair shaft. 14. WHO SHOULD BE CHECKED FOR HEAD LICE? The answer to this is everyone who has hair on their head. It is true that head lice are more prevalent in children, but many adults are also affected. It is believed that adult carriers are one of the main sources of head lice in our communities. 15. WHEN AND WHERE SHOULD SCREENING TAKE PLACE? Screening for head lice should take place on a regular basis (at least once a week) especially if head lice have been reported in a community. Screening should take place in the home as it is not practical to expect the schools or the health nurses to be able to screen whole communities effectively.
16. CAN YOU TELL HOW LONG LICE HAVE BEEN PRESENT? The duration of an infestation can be estimated by measuring the distance that the oldest nit is from the scalp. Hair grows at approximately 1cm per month. The female louse lays her eggs as close to the scalp as possible and as the hair grows the egg moves with it. If nits are found at a distance of say 2cm from the scalp, then it follows that the lice have been resident for at least two months. 17. WILL CUTTING HAIR SHORT AND KEEPING IT CLEAN PREVENT REINFESTATION? It is a myth that head lice prefer long dirty hair. If anything, the opposite is true. Long hair can actually impede the louse s journey from head to head and so cutting the hair short will only help the louse. Dirty hair is also a disadvantage to the louse as grease and dirt make movement around the scalp more difficult, feeding is unpalatable and the eggs do not stick to the hair shaft properly. 18. DO LICE CARRY DISEASE? Head lice are not implicated in the transmission of any disease. If left untreated, however, secondary bacterial infections may occur as a result of scratching. These infections may need to be treated with antibiotics. Individuals who have had an infestation for a long period of time may start to show symptoms of general malaise and a lack of concentration. These symptoms led to the origination of the phrases feeling lousy and nit wit. 19. WILL WASHING WITH REGULAR SHAMPOO CURE HEAD LICE? Regular shampoo has no effect on the head louse. When the hair is washed the louse goes into a state of suspended animation, clinging tightly to the hair with its claws while waiting for conditions to improve. In this way the louse survives not only hair washing but also rain, seawater and the chlorinated water of swimming pools. 20. WHAT SHOULD YOU SEE AFTER TREATMENT? Dead and dying lice will be seen in the rinsing water and can easily be combed out of the hair after treatment, using the comb provided. Some of the lice may still be mobile but the fact that they have released their grip on the host s hair means that they will die soon. The dead eggs and empty shells will remain glued to the hair.
21. SHOULD THE DEAD EGGS AND NITS BE REMOVED? Removal of the dead eggs and nits is always a difficult and sometimes painful task and the question may be raised as to whether it is actually necessary. There are two situations where it is necessary; The first is for cosmetic purposes. If there has been a heavy infestation the white nits may be very conspicuous and unsightly and warrant removal. The second is for more practical reasons. Take for instance a child who has been treated for lice, but has not had the dead eggs and nits removed. When checking for re-infestations it will be difficult to tell if the nits are from a new infestation or from the original one. If all nits had been removed after treatment, the appearance of new nits would herald the arrival of a new infestation. It is for this second reason that schools insist on the removal of all the nits before the child can be readmitted to classes. 22. SHOULD THE TREATMENT BE REPEATED? One application of Para Special or Para Plus Lice Spray is sufficient to kill lice and nits on the head. A repeat application should not be required, provided the manufacturer s instructions have been followed. 23. WHY DO HEAD LICE KEEP COMING BACK? If the instructions on the anti-lice preparation are carried out correctly, all lice and their eggs will be effectively destroyed. Why is it then that sometimes, only a few days after treatment, adult live can again be detected on the scalp? The reason for this is unlikely to be as a result of treatment failure, and is probably due to re-infestation taking place. Unless all contacts are alerted, screened and treated for head lice at the same time, reinfestation is highly probable. This situation is especially prevalent in schools where not all those children who have lice are treated simultaneously. It may also be a problem in the home. For example, an aunt or grandmother may have visited the home prior to the discovery that members of the family have head lice. She may have picked up a louse from one of the children, but because her head does not itch, she is unaware that she has become a host to this insect. A week later head lice are discovered and everyone in the home is effectively treated. Two days later the aunt or grandmother returns and when kissing the children hello, inadvertently passes the head lice back. The whole situation is compounded by the fact that head lice can be difficult to detect by people who do not know what to look for, and may be present on an individual for a number of months before action is taken. In the meantime lice are being freely transmitted to other individuals.
24. WHAT OTHER PRECAUTIONS MUST BE TAKEN? Although transmission is unlikely to occur via combs and brushes, it is always a good idea to wash them on a regular basis. If head lice have been found, these articles may be washed with the anti-lice preparation used to treat the infestation. Bedding and clothing may be washed and ironed but it is not necessary to fumigate the home for head lice. 25. HOW TO PREVENT INFESTATION? The only way we could prevent the spreading of head lice would be to cease all physical contact with fellow man. This is obviously totally impractical and the best we can do is to remain alert for their presence. The following measures will help with early detection and halt the spread of these small insects; Groom the hair often and thoroughly. Brushing and combing the hair increases the chances of injury to the louse and as loss of a limb is usually fatal to the louse, regular grooming can help prevent establishment of the colony. Use a fine-toothed detection comb on wet hair to screen for head lice. This should be done regularly especially if lice have been reported in the area. Check for tell-tale signs such as cast skins and waste products on the bedding and clothing. If head lice are detected, everyone who has been in contact with that individual in recent weeks must be informed and treatment should be carried out on all infested individuals on the same day to prevent reinfestation. 26. CAN YOU USE ANTI-LICE PREPARATIONS TO PREVENT RE-INVESTATION? From a practical point of view shampoos and lotions are difficult to use on clothing etc. However, both Para Special and Para Plus Lice Sprays can be sprayed on collars, hats, scarves etc. They can also be sprayed lightly over the surface of DRY hair. This preventative spraying should not continue for longer than a week at a time. 27. HOW DO YOU TREAT HEAD LICE? Once discovered, it is important to get rid of the head lice as soon as possible. Ask advice from your pharmacist, who will recommend effective treatment, rather than some oldwives tale remedies which have not been proved to be effective and may have no value at all.
Follow the instructions that come with the preparation. Ensure that all adults and children who have been in contact with the infected person are informed and treated at the same time. 28. HOW DO YOU TREAT HEAD LICE WITH THE PARA RANGE OF PRODUCTS? Read the package insert. Before use, test for sensitivity on a small patch of skin on the inner arm. Use the aerosol tube to direct the spray onto the base of the hair shaft. Use short one second sprays until the scalp and hair base are moist. Wash the hair with a regular shampoo and rinse well. Eliminate dead lice and nits by means of a fine-tooth comb. To avoid any recontamination, also disinfect the clothes and bedding. One application of PARA SPECIAL LICE SPRAY (Reg. No P/13.4.2/115) is enough to kill lice and nits within 30 minutes. One application of PARA PLUS LICE SPRAY (Reg. No. 29/13.4.2/0243) is effective within 10 minutes. DO NOT LEAVE ON THE HAIR FOR LONGER THAN 10 MINUTES. ONE APPLICATION PER INFESTATION IS SUFFICIENT. DO NOT USE ON CHILDREN UNDER THE AGE OF 30 MONTHS. DO NOT USE PARA SPECIAL LICE SPRAY or PARA PLUS LICE SPRAY ON IRRITATED OR BROKEN SKIN. Para Nit Remover is a hair rinse gel with conditioner, which will assist in detaching nits after anti-lice treatment.