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Head Lice Ectoparasite of Humans Infestation Prevention


Last updated 09/21/2022

This creepy crawling pest has been with humans for centuries. All civilizations have had to deal with their presence. Head lice ectoparasite.

They are found everywhere in the world. But an infestation is more common among pre-school children in childcare, elementary school, and household members of infested kids. Head-to-head contact often occurs during game playing, sports activities and as a sign of affection. So, the louse is easily transmitted from one child to the next.

According to the CDC, an estimated 6 to 12 million infestations happen every year in the United States. This is with children aged 3-11. Infestation of head lice in the US concerning African Americans is not often reported versus other races.

And some studies propose that girls are more common than boys in getting head lice. In short, this could be due to girls having more head-to-head contact.

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Head Lice Ectoparasite

The medical term for head louse is pediculus humanus capitis. Some refer to them as insects. Head lice ectoparasite meaning the organisms live on the outer skin of their host. When many living insects are found it is an infestation.

These insects can be discovered on the hairy areas of the head, especially the scalp. Hair on eyebrows and lashes of humans are sparse and head lice parasite are less common.

Head lice can’t fly. In other words, they are wingless. Crawling and grasping the hair with their claws is how they get around.


Other Ectoparasites:

  • Fleas
  • Ticks

Lice Life Cycle

There are three stages to their life cycle.


Lice eggs are called nits. The adult female head louse lays her eggs close to the scalp at the base of the hair shaft. For survival the egg must stay warm. In short, the nits are very tiny (similar to a knot of thread). To sum up, they are hard to view with just your eye.

Coloring of the eggs can be yellow or white. Nits are oval shaped and secured to the hair shaft with sticky cement like substance. So, removing them even after the nymphs hatch and leave empty casings is difficult.

The egg is sometimes confused with dandruff, scabs or hair spray droplets. Normally found about ¼ inch from the base of the hair shaft are eggs most likely to hatch. Hatching eggs can take around 8-9 days. However, eggs found more than ¼ inch from the hair shaft base probably already hatched, didn’t develop, are empty or casings.


An immature louse is referred to as a nymph, and hatch from the nit. It is smaller in size but similar to the adult head louse. Nymphs require human blood to feed on. Moreover, they become adults around 9-12 days from hatching.

Adult Louse

Once the louse is fully grown into an adult it is around the size of a sesame seed. Females are typically larger compared to the males. Furthermore, she can lay around six eggs per day.

It has an obligate shape with six legs containing hook-like claws to grip the hair shaft. So, this is how they move. Head lice can range in color from tan to grayish white. The adult can be darker if the host has dark hair.

It must continue to feed on blood. And as an adult it can live around 30 days on someone’s scalp. But can die inside one to two days when disconnected (say it fell off) the host. They can even survive underwater for about six hours.

Above all, they avoid light, so it is hard to spot them. You may need to use a magnifying glass to see the tiny critters.

Head Lice

What is Pediculosis?

Head lice are from the sub-order Anoplura. Their family name is Pediculidae. Although pediculosis in humans typically refers to lice infestation of any area, the term is occasionally linked to pediculosis capitis. Further the infestation involving the human head (scalp) with the certain head louse.

Who gets Pediculosis?

Anyone can become louse infested if exposed. Pediculosis is easily transmitted during direct head-to-head contact from one individual to another. To clarify, this is the greatest risk. School settings are common for head lice infestations.

Furthermore, spreading head lice through contact with clothing (like hats, scarfs and coats) or personal things (like combs, brushes or towels) used by an infected person is uncommon.

Most importantly, one’s personal hygiene or cleanliness of the home or school does not increase your risk for head lice.

Symptoms for Head Lice

Firstly, the itching and scratching will be noticed in the area that lice feed. Likewise, there could be a tickling sensation as something moving through the hair. Severe scratching at the back of the head or behind the ears should lead you to search for eggs (nits).

As a result, sores develop on the head because of the scratching. This is an allergic reaction due to the bites. To sum up, bacteria found on the person’s skin enters the wound causing an infection (pyoderma).

It could take two or three weeks to recognize the connection between itching and an infestation. In addition, the time that lice remain alive on you, is the spread of pediculous.

Head lice are not acknowledged to transmit disease. So, they aren’t thought of as medical or public health hazards in the US. However, their presence can be annoying. Irritability and lack of sleep is another observance. That is to say these pests are more active in the dark.

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How do Head Lice Eat?

When the head louse is hungry it moves near the scalp surface searching for an acceptable vein. It pierces the skin using its mouthpart and releases saliva to the wound. As a result, this keeps blood from clotting while it feeds.

The head louse takes blood through two small pumps attached to its head. Because the parasite is pretty transparent you can actually see this process using a microscope. Viewed is a thin line of blood running from its mouth pumping through the head and entering the intestine.

Head lice never leave their host because they require several meals within twenty-four hours. In other words, they need human blood to survive.

Wet Hair Method

It is recommended to wet hair with hair conditioner or another product before examining the scalp. This makes it easier to observe any nits or live lice. Most importantly, don’t rush while combing through your child’s hair using a fine-tooth comb (nit comb). Certainly, run the comb from the scalp to the ends of the hair.

How to Diagnosis Head Lice

Best diagnosis of an infestation is through noticing a live nymph or adult louse on the person’s scalp or hair. This is circling the ears and behind as well as the nape of the neck behind the head. However, this can be a challenge as nymphs and adult lice are tiny, fast moving and shun light.

Having a magnifying lens and a fine-toothed comb can aid the search for live lice. Nit combs are available online or at your local pharmacy.

When no crawling lice are viewed, nits securely attached ¼ inch from base of hair shafts is a strong suggestion. Although, this does not confirm someone is infested and should seek treatment. Nits could also be dead or already hatched if found more than ¼ inch away from the hair shaft base.

But if you are unsure whether a child has head lice or not contact a specialist. This could be a healthcare provider, dermatologist or your child’s pediatrician.

Your dermatologist can diagnose an infestation by using a fine-toothed comb to search for nits in your child’s hair. A specialized light known as a wood’s lamp may also be used causing the nits to appear bluish. But the wood’s lamp casting a bluish light doesn’t mean there are live lice on the scalp.

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Head Lice Ectoparasite Prevention

The best advice to prevent getting head lice ectoparasite are to not share items that touch the head. In addition, avoid direct head-to-head contact with an infested individual.

Coach your kids on not sharing:

  • Their combs
  • Brushes
  • Hats
  • Scarves
  • Hair clips
  • Scrunches
  • Helmets
  • Headphones
  • Pillows
  • Ribbons

Health education should be provided on the lice life cycle and correct repeating of treatment. For instance, washing the clothing and bedding in hot water or dry cleaning. This ensures destroying lice and their eggs.

To sum up, regular direct inspection of your young children for head lice should be performed. Likewise, this could include examining their body and clothing as well.

This is especially important if they are in:

  • School
  • Institutions
  • Nursing homes
  • Summer camps
Wrapping it up

Head lice have had a history with people since the dawn of time. Their presence can cause embarrassment, but anyone can get them. For instance, the ectoparasites aren’t connected to dirtiness or poor hygiene.

The bug can be easily transmitted from one person to the next. This is mainly through direct head-to-head contact. In addition, practice avoiding this habit and sharing personal items to prevent the spread of pediculosis.


Mary is the founder of All About Our Skin. Former esthetician and CPC. Enjoys researching skincare and has been studying our skin for the past fifteen years.

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