What are Head Lice?
Head lice (pediculus humanus capitis) are very small parasitic insects which live in human hair and feed off blood from the scalp. While people might find these creatures repulsive, they are not a public health hazard and don’t carry disease.
Infestations are most prevalent in children between the ages of three and eleven. There are an estimated six to 12 million cases in this age group in the US each year.
Head lice are unable to hop, jump or fly; they move by crawling and spread as a result of direct contact. Although not unknown, catching head lice from personal items belonging to an infested person is unlikely. (1)
Head lice live exclusively on human heads and feed on human blood. They could find their way onto personal items including: clothing, hair brushes or hats. Household items like towels, pillows or couches can also harbor lice.
Head lice are only able to survive for about a day when they are not close to the scalp. They need to feed approximately every three to four hours. Consequently, when not on the scalp of a human host, they will dry up and die. (2)
These critters don’t discriminate either; they like a clean head of hair as much as a dirty one. Their only objective is to find food to survive, which means biting your scalp to feed on the blood. (3)
Symptoms associated with a head lice infestation include:
You may feel something is tickling your scalp or moving around in your hair, or on your head. (4)
When head lice bite the scalp to feed, they transfer saliva onto the location of the bite. This can cause an allergic reaction and make the scalp itch. This is often more prevalent at night when the lice are most active.
Although itching is the most common symptom, it is not always present. Also, it can take up to a few weeks for this symptom to manifest after the onset of an infestation. (5, 6)
Irritability and Sleeplessness
We have mentioned head lice are active at night; therefore, this is when you are most likely to experience itching. It can interfere with your quality of sleep and make you irritable during the day. (7)
Sometimes the urge to scratch to relieve the itch can be irresistable. As a result of scratching, a rash or sores might form on the scalp. These have the potential to become infected with bacteria. (8)
The glands in the neck (lymph nodes) may become swollen. (9)
Head lice have a three stage life cycle: the egg (nit), the nymph and adult.
Stage One – Eggs (Nits)
This is the first stage in the life cycle of a head louse. Lice eggs (nits) are laid at the base of hair shafts, close to the scalp. They need to be within about a quarter inch of the scalp to stay alive. Nits found further along the hair shaft could be empty casings or remains of those unable to survive.
The eggs bind firmly to the shaft of the hair; they usually take about eight to nine days to hatch. Nits are not easily visible, being less than one millimeter in size. Oval in shape and white or yellowish in color, they can be confused with dandruff.
The most common location of nits is near the back of the ears, or in hair close to the base of the neck. (10, 11)
Stage Two – Nymph
The second stage of the life cycle sees the egg hatch to form a nymph. Resembling an adult louse but smaller, less than the size of a sesame seed, it is lightish brown or grey in color. Nymphs feed on blood and usually reach maturity in approximately nine to twelve days. (12)
Stage Three – Adult
The final stage in the life cycle sees the head louse fully grown, measuring about two to three millimeters. Appearing whitish grey or tan in color, it has six legs with hook-like claws, enabling it to cling to the hair. Lice don’t have wings; they crawl to move around the head or onto another person.
Female lice are generally larger than males; they are capable of laying up to six eggs a day.
Adult head lice need to feed on blood to survive; they can live for about 30 days. When they fall off the head, they will die within a day or two.
While uncommon, head lice or nits can sometimes be found on the eyebrows or eyelashes. (13)
Diagnosis of the presence of head lice can usually be done at home. Use a fine toothed comb, or a lice comb, and a bright light. Shine the light on the head while going through the wet hair to reveal lice or nits.
The best way to do this is to separate the hair into sections. Start from the scalp, combing slowly through each section. You may see adult head lice or nits attached firmly to the hair near the scalp.
There are several over the counter products available to treat head lice, without the need for a prescription. When using these products, follow the instructions carefully.
Apply the product only to the head area and wash it out with running water from a tap or shower hose. These products are not meant for use in the bath or shower; skin contact should be limited.
Using more than one type of product can be harmful, so don’t mix them. Be sure to use only the directed amount; using too much can again be harmful. Also, only leave the product on the head for the amount of time directed by the instructions. Put on clean clothing after finishing the treatment.
Check the hair and scalp about eight to twelve hours after it has been treated. There may still be some slow moving head lice. This is nothing to worry about; not all lice will be killed immediately.
However, if the adult head lice are as active as when first examined, the product might not have worked. In this situation, you should speak to a medical professional, such as a dermatologist, for advice.
Following treatment, do not wash the hair for two days. The product will continue its work on any remaining head lice. Also, comb the hair thoroughly with a lice comb once a day for two to three weeks. This will remove any dead lice and nits, or any live ones that remain.
About seven to nine days after the first treatment, most products recommend a second application. This will ensure any remaining nits which may have hatched, or surviving lice, will be eradicated.
As with the first treatment, follow the instructions carefully. Do not wash hair for two days and continue to use a lice comb for two weeks.
Lice combs have very narrow spaces between the teeth, enabling them to remove nits and lice from the hair. Using them together with a treatment will improve the chances of eliminating the lice.
While drastic, another way to remove the head lice and nits would be to shave the head completely.
Family and Friends
Anyone who has been in close contact with an infected person could also have an infestation of head lice. Therefore, it’s prudent to check the hair of family and friends regularly, about every 10 to 15 days, for signs of infestation.
Close family should all be treated at the same time, to prevent reinfestation. (14, 15)
If treating head lice at home doesn’t work, or if you are concerned, a doctor or dermatologist can help. There are prescription medications available for the treatment of head lice infestation.
Again, as with over the counter medications, ensure you follow the directions and the advice of your doctor carefully. (16)
Treating Your Home
As well as treating an infected person, treatment of the home is necessary to prevent reinfestation.
Head lice and nits can be killed following exposure to temperatures over 130 degrees fahrenheit for five minutes or longer.
Wash clothing, bedding and headwear used or worn by someone with an infestation up to two days before treatment. The hottest cycle possible should be used. Any items which can’t be laundered at high temperatures should be sealed in polythene for two weeks.
Soak hair brushes, combs and hair ornaments in water at a temperature above 130 degrees fahrenheit, for at least five minutes. Items like soft toys or pillows can be placed in a dryer on its hottest setting for ten minutes or more.
Carpets and soft furnishings should be vacuumed to remove any lice or hairs that might still have viable nits attached. (17)
What are head lice? Head lice are very small parasitic insects which live in hair and feed off blood from the scalp.
What are the signs of head lice? The main symptom of a head lice infestation is an itchy scalp. A tickly feeling on the head, irritability and sleeplessness as a result of the itching can also be experienced.
How do you develop head lice? Head lice are caught from head to head contact. This is often the case with young children who play closely together in school or at home.
How are you diagnosed for head lice? Examination of the hair and scalp using a very fine toothed nit comb will reveal the presence of head lice. The eggs can be seen attached to the hair shaft, or adult lice seen moving around.
What is the best treatment for head lice? There are over the counter medications available to treat head lice. If these don’t work, then a doctor can advise and prescribe different treatments.
What are the long term complications of head lice? Head lice do not carry disease and can be successfully treated. Consequently, the long term prognosis is good.
Are head lice considered a disability? A few days off school or work might be necessary while treatment is ongoing. However, head lice are not considered a disability.
Is there a cure for head lice? Careful treatment will eradicate an infestation of head lice. It’s important to follow the directions on medication and complete follow-up treatment as necessary.
Are head lice life threatening? While this condition might be unpleasant, it is not life threatening.
Head lice are a parasitic infestation living in the hair and feed off blood from the scalp. When they bite, their saliva can cause an allergic reaction leading to itchiness.
This common complaint is prevalent in young children, and anyone who works with them. Close contact allows the lice to crawl from one head to another.
While unpleasant, the good news is this condition can be easily treated by over the counter medication or treatment prescribed by a doctor.