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Human Louse

Last updated date: 28th May 2024
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What is a Human Louse?

Human louse, also scientifically known as the Pediculus humanus and commonly known as the body louse, is a well-known species of the sucking louse that belongs to the Pediculus family, order Phthiraptera, and suborder Anoplura. It is found in almost all places where humans live; they feed on their blood, which classifies them as primary carriers of the epidemic typhus and several other louse-borne diseases. 

For example, relapsing fever and trench fever. There are a total of two subspecies of a human louse, they are:

1. Pediculus Humanus Capitis- also commonly known as the head louse

2. Pediculus Humanus Humanus- also commonly as cootie or body louse

Read below to learn more about these subspecies.

Pediculus Humanus Cavities

They are also known as head lice and are parasitic insects that are found on the heads of human beings. Pediculosis is the term coined for infection with head louse or head lice. It is, however, different from the pubic louse or scientifically known as the pthirus pubis, which, as the name suggests, causes pubic hair infections. Young head lice are also called redbacks due to their blood-red colored backs after they feed. Similarly, they are also called gray backs, and black backs after digestion are complete. 

Head louse are tougher and smaller compared to body louse. Young lice are 

The head lice infection is very prevalent in human beings, considering it has been around since medieval times. The exact statistics or data of the frequency of infestation is unknown, but it is estimated to grow 6-12 million cases every year. Head lice can be spread from one individual to another very easily. Therefore, any person that comes in touch with someone who already has head lice or contaminated personal things like clothes, combs, and other belongings is at high risk of getting head lice.

In an example of a normal scenario, data shows that it is extremely easy to acquire head lice from other people during pre-school or elementary school. Children of 3-11 years of age, their parents, and other family members are usually infected the most with head lice. In addition, girls and women are said to contract more head lice more often than boys and men. 

Who Do Children Get Head Lice From?

Children usually don't mind their surroundings often, which makes them high at risk of getting head lice. Following are the ways they can get head lice:

  • Coming in contact with a person who already has head lice. This can happen during playschool, camp, slumber parties, sports activities, etc.

  • Using dirty and infected towels, combs, and brushes.

  • Wearing infected clothes, for example, coats, sweaters, sports uniforms, scarves, hats, hair ribbons, and so on.

  • Lying on couches, pillow, bed, carpet, bed, or stuffed animal has recently been in touch with an infected person. Although there is evidence that the chances of getting it are significantly less if more than 48 hours have passed since the first contact.

The life Cycle of Head Louse

There are three forms of head lice throughout their life cycle. They are:

a. Nit- it is the first stage of head lice. Nits are lice eggs. They are very minute, which makes them hard to see and recognize. Often, they are confused with hair spray droplets and dandruff. They have a stronghold and are firmly attached to the shaft of the hair. Appearance-wise, they are oval-shaped with not more than 2 to 3 mm in length. Their color varies from white to yellow and takes about 7 days to hatch. 

b. Nymph- it is the second stage of head lice. When the nit hatches after a week into a baby louse, it is then known as a nymph. Their physical appearance resembles that of an adult louse, except they are smaller. They also take about 7 days to mature into adult nymphs after hatching. Nymphs feed on the human blood for their survival.  

c. Adult- it is the third and final stage of head lice. An adult louse is the same size as a sesame seed. It has about 6 legs and grayish-white to tan in color. The adult louse looks much darker in color in people who have darker hair. Female adults lay nits and are much larger as compared to male adults. An adult louse can survive at least 30 days on a human's head. For them to live, they will constantly feed on human blood. If the lice fall off from a person's head under any circumstances, they will die in two days.

Life Cycle: The female adult louse lays nits that take 7 days to hatch. After they hatch, they are known as nymphs, and they take 7 days to mature into an adult louse. Then, the female adult louse mates with a male adult louse to lay nits, and thus, the cycle continues. 

Where are the Head Lice Commonly Located?

The lice scientific name is Phthiraptera. They are commonly found on the scalp of the head, which is behind the ear and near the base of the neckline behind the head. They have hook-like claws, which help them to hold on to the hair. Their claws are found at the base of their 6 legs. Head lice are hardly found on the eyebrows, body, or eyelashes. 


What are the Signs and Symptoms of a Head Lice Infestation?

The following are the signs and symptoms of head louse infestation are:

  • Itching- which is caused by an allergic reaction due to the head lice bites.

  • Irritability

  • Tickling- a tickling feeling or feeling like something moving in your hair.

  • Scratching- also causes sores on the head and it can be infected sometimes.

How Can Medical Consultants Diagnose a Head Louse Infestation?

It can be inspected by glancing closely through the scalp and hair for nymphs, nits, or adults. Finding an adult or nymph may be hard, but there are generally few of them, and they can quickly move around the head while searching through fingers. Moreover, the existence of nits near the scalp of the head confirms that the human is infected. 

One can figure out how old the infestation is by looking at judging the distance between the nits and the scalp. For example, if the distance between the scalp and the nit is 1/4 inch, the chances are that it is an old infestation.  

If one is unsure whether someone has head lice then, the diagnosis should be made by a professional medical consultant, local health department professional, or school nurse. 

According to Doctor Loffeuspenky, his experiment found out that usage of a louse comb is much more effective than visual inspection when you're screening for head lice infestation. 

Pediculus Humanus Humans

Also known as body lice, they are parasitic insects that infest the body and feed on human blood. The body lice scientific name is Pediculus humanus. They live on bedding and clothing previously used by an infected person. They often lay eggs near or on the seams of a person's clothing. They usually move the human skin to feed themselves. The infestation can be easily widespread under crowded poor hygiene living circumstances, for example, a refugee situation, homelessness, natural disasters, or victims of war. For instance, in the United States of America, body louse infestation is found in the transient homeless population who are deprived of basic hygiene facilities like a regular change of clothes and bathing. Body lice infestation is improbable on any person who showers/bathes regularly and has access to fresh, clean, laundered bedding and clothes. 

The Life Cycle of Body Lice 

There are three forms of body lice throughout their life cycle. They are:

a. Nit- it is the first stage in the life cycle of body lice. They are body lice eggs, and they can be easily recognized in the seams of clothing, specifically around the under armpits and waistline.  Body louse nits can also be periodically attached to body hair. They are yellow to white and oval looking. Unlike head lice that take about a week to hatch, the body lice take about 1 to 2 weeks to hatch. 

b. Nymph- It is the second stage in the life cycle of body lice. They are baby body lice that hatch from the eggs or nits. It looks exactly like the adult body lice but just smaller in comparison. Nymphs take about 9-12 days to mature into adult human lice. To survive, the nymph should need human blood. 

c. Adult- It is the third stage in the life cycle of body lice. Like a head louse, the body louse is also the size of a sesame seed, tan to greyish-white in color, and has six legs. The female adult body lice lay eggs or nits. To live, it is the lice's scientific nature to feed on human blood. If the body lice fall off someone's body, it will die in 5 to 7 days.

Life Cycle: The female adult body louse lays nits that take 14 days to hatch. Once they hatch, they are known as nymphs, and they take 9-12 days to mature into an adult louse. Then, the female adult louse mates with a male adult louse to lay nits and thus, the cycle continues. 

Where are the Body Lice Commonly Located?

The human body louse is generally found on bedding or clothing utilized by infested humans. However, sometimes body louse can be easily visible on the body when they start to feed.  

Symptoms and Signs of Body Lice

Pruritus or intense itching and rashes are caused by an extreme allergic reaction to the louse bites on the body. They are some of the widespread indications of body lice infestation. When this infestation continues for a long time, the more bitten part of the skin becomes thick and is discolored. This particularly happens around the midsection of the human anatomy (upper thighs, groin, and waist.) This bodily condition is also known as vagabond disease. 

Other known effects of body lice infestation are body sores. In some cases, the body sores are also infected with fungi or bacteria.

Can the Body Louse Spread Disease?

Research has shown that body louse is carriers of louse-borne relapsing fever, trench fever, and epidemic typhus. Even though epidemic typhus is not widespread anymore, the chances of this outbreak become particularly high during both man-made and natural disasters, war, prisons (people living in a confined area without access to proper sanitary conditions), and civil unrest. 

How are They Diagnosed?

It can be diagnosed by locating eggs/nits and crawling body lice on or near the seams of clothes. Occasionally, it can also be found on the human skin, feeding and crawling. Furthermore, body lice and their eggs are large enough to be spotted by the naked human eye. One can also use a magnifying lens if necessary to find nits or lice. A medical professional should make a complete diagnosis if you want to be sure about the infestation. 

FAQs on Human Louse

1. How is Body Lice Treated?

Ans: One can treat and prevent body lice by maintaining and improving personal hygiene. Regular changes of clothes, daily showers, weekly change of bedding, towels, and other clothing items. The clothes of the infected person should be laundered or washed using hot water and machine fired by using the hot cycle feature. Other treatments include using pediculicide, a medication that is known to kill lice. However, it is used in extreme conditions and is generally unnecessary if the person maintains personal hygiene.

2. What is the Difference Between Head Lice and Dandruff?

Ans: Oftentimes, it is seen that the head louse is confused with dandruff. The difference between them is that dandruff can be easily characterized by combining the hair or plainly rubbing it. Dandruff easily falls off or removed, but head lice have a strong grip due to the claws can't be shaken off.

3. Can a Black Light Assist in Diagnosing Head Lice Infestation?

Ans: Yes, blacklight can be used to check if there are nits that have living lice in them. However, a few reports suggest that nits with living lice in them will turn fluorescent.