Phthirus Pubis: Vector, Causative Agent, Structure And Size

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Phthirus Pubis: Vector, Causative Agent, Structure And Size
Phthirus Pubis: Vector, Causative Agent, Structure And Size

Video: Phthirus Pubis: Vector, Causative Agent, Structure And Size

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Video: Lice (Head, Body and Pubic Lice) | Pediculosis | Species, Symptoms and Treatment 2023, February

Page content

  • Reproduction and life cycle of an insect
  • How dangerous is Phthirus pubis
  • Why and how does infection occur?
  • Main risk groups
  • Signs of the disease
  • Treatment principles and treatments for pubic lice


  • 10 curious facts about the life of pubic lice
  • Pubic lice myths

    • Myth one: a tumor of the genitals and temperature are signs of pubic lice.
    • Myth two: you can get pubic lice in a public toilet.
    • Myth three: you can be treated with hormonal ointments, antibiotics, and even bleach with lysol
  • You can defeat parasites!

Phthirus pubis is the Latin name for an ectoparasite. The name in Latin is used in international practice. The external appearance and internal structure of the plow has the following features:

  • The size of a flattened body, reddish or brownish, does not exceed 3 mm. Females are usually 1.5 times larger than males.
  • Small head with 5-segmented antennae.
  • Wide chest, practically merging with a short, tapering abdomen.
  • The oral apparatus is a proboscis, in which 2 pointed needles are hidden inside the head. The parasite is characterized by profuse salivation. When saliva enters human blood, it acts as an anticoagulant, preventing it from clotting and contributing to itching.
  • The stomach is designed in such a way that the ploshchik can actively suck blood. In the process of feeding, the digestive system, like a pump, makes up to 4 contracting swallowing movements per second.
  • 6 paws, each of which is larger than the previous one. The first forelimbs are poorly developed. The second and third are equipped with special claws that help the parasite to securely attach to the host hairs. Due to the special structure of the legs, the ploshchik can only live on hair with a triangular section. Those that have a round section (on the head) are not suitable for her.
  • 2 simple eyes - age spots. By and large, the parasite does not need the organs of vision, since it is oriented in space by smells.

This ectoparasite is so small that it is impossible to examine it in all details with the naked eye. This can only be done with a microscope. You can see what the ploshchit looks like in the photo above.

What to do in such a situation? To get started, we recommend reading this article. This article details the methods of dealing with parasites. We also recommend contacting a specialist. Read the article >>>

Reproduction and life cycle of an insect

With sufficient nutrition, the female Phthirus pubis is ready to mate. This does not happen earlier than 1–2 days after the last molt. The female carefully chooses a place for laying eggs. This happens on the owner's hair, to which, with the help of a special adhesive, she sticks them, enveloping them with a special liquid. The resulting capsule is called a nit. The female attaches each subsequent egg to a new hair. She usually lays up to 3 eggs per day.

The optimum temperature for masonry is 28–32 ° С. Other temperature conditions slow down the development of eggs. In some cases, they can go into temporary hibernation. Nits, consisting of a capsule and a conical lid, through which an adult parasite subsequently emerges, develop within 5–8 days.

The matured larva gnaws at the lid and, taking in air, forms pressure in the capsule, with the help of which it leaves its home. After a few days, she molts, turning into a nymph of the first and then the second stage. After the last molt, the sex of the future parasite is determined and transformation into a sexually mature individual occurs.

The full life cycle of a plow is about 1 month. Development from egg to adult takes about 15 days.

Phthirus pubis
Phthirus pubis

How dangerous is Phthirus pubis

Fortunately, these insects are not carriers of dangerous diseases, unlike the body and head species. But any bites cannot pass without a trace. The consequences are manifested in the form:

  • Itching and bite marks;
  • Bluish spot at the site of the bite.
  • Since the bites are combed, many papules and pustular inflammations form in their place. And if the case is neglected, then pyoderma occurs.
  • If eyelashes and eyebrows are affected, blepharitis and conjunctivitis may develop.

Pubic lice, unlike their relatives, head and body lice, have a more crab-like structure.

Why and how does infection occur?

It should be noted that, despite the sufficient awareness of the population about the existence of lice, plots are quite common. They parasitize equally on both men and women. Even children can be affected under certain conditions.

It is interesting that fashionable trends, it turns out, can influence the development of certain epidemiological situations. So it happened with pubic lice. The fashion for shaving pubic hair has deprived plovers of their rightful place of residence. And the number of cases of infection has decreased.

Pubic lice can be contracted after close contact with a sexual partner. Lice simply crawl from a sick person to a healthy one.

The most difficult epidemiologically are poor countries, especially in Africa, with unsanitary conditions and promiscuous sex. After all, the main routes of transmission of these types of lice are sexual contact. The situation is aggravated by the fact that signs of infection appear only after a month, and a person can be the source of the disease all this time without knowing it. Therefore, people who observe hygienic requirements for body and clothing can become infected.

Why and how does infection occur?
Why and how does infection occur?

Main risk groups

Phthirus pubis are more common in crowded societies where people are in close contact with each other. Risk more:

  1. Homeless;
  2. Refugees;
  3. People who are in places of hostilities;
  4. Bath and laundry workers;
  5. Prostitutes;
  6. Hairdressers;
  7. Servicemen with barracks accommodation;
  8. Living in hostels;
  9. People who are in pre-trial detention or serving sentences.

There is a small chance of contamination through a public towel, hotel or train linen.

Signs of the disease

As stated above, symptoms do not appear immediately after infection. For a month, a person is only a carrier of the parasite. And if he leads a hectic life, you can imagine how many people will be infected. And then the process develops exponentially. Thus, a huge number of people can get sick in a short time. Tidy people who value family ties are the least at risk.

But nevertheless, if an infection has occurred, then soon the person will have sensations of severe itching in the place where the ploshchit has penetrated the skin. The pubis usually itches. The itching can be very severe, or it can hardly be felt. It occurs due to the ingress of insect saliva into the wound. And all people are different: with different reactions to external influences, with different manifestations of the immune response, and finally, with different patience. And what is unbearable for some, others easily endure.

photo: 1 - large accumulations of nits visible to the naked eye; 2 - skin reaction at the site of the bites (often the rash takes on a characteristic bluish tint)

Signs of the disease
Signs of the disease

By constantly scratching the itchy area, a person causes additional damage to the skin. It can peel off, crusts and dandruff form on it. The appearance of dermatitis or an eczema condition is possible.

In severe cases, excoriation appears - areas of severe damage. Their danger lies in the increased risk of bacterial infections (including STDs). It is much easier for bacteria to enter the bloodstream through damaged skin. As a result, inflammation develops.

Itching alone can not identify pubic lice. Indeed, many other diseases are also accompanied by this symptom. Therefore, it is difficult to differentiate at home. It is also very difficult to see the parasite with the naked eye (it is much smaller than its parent brother).

Another symptom of phthiriasis is a rash, which is represented by numerous papules, vesicles and bluish spots on the skin. By spot size - no more than 2–3 mm. In the area of ​​the bite, the skin thickens. It is rough to the touch, with deep lines and wrinkles. The rash can be not only the result of a bite, but also allergic.

Localization of the area around the eyelashes leads to blepharitis. But the most irrefutable sign is the finding of the parasites themselves and their larvae.

Treatment principles and treatments for pubic lice

The following activities are the basis for effective treatment and prevention of the spread of pubic lice:

  • Two stages of therapy, which are necessary in connection with the vital functions of the pubic louse.
  • Mandatory preventive treatment for all people who have had close contact with the patient.
  • Measures for the disinfection of patients' belongings.

For the treatment of pubic lice, special chemotherapeutic substances are currently used - pediculocytes, which are insecticides that selectively act on lice and nits. Pediculocytes do an excellent job of eliminating pubic lice and nits, but at least two treatments should be carried out, since it is necessary to destroy the next, emerging generation of the insect.

Before the advent of pediculocytes, a variety of compounds were used as insecticides against pubic lice to treat the affected surfaces. So, the following formulations have been widely used to combat pubic lice:

  • soap and kerosene mixture;
  • Sulfuric ointment;
  • tar ointment;
  • benzyl benzoates.

Today, the most effective pediculocytes are drugs that contain pyrethrins as active ingredients, or the drug Lindane. Pyrethrins include malathion, carbaryl, and permethrin. Moreover, the highest efficiency in the treatment of pubic lice was demonstrated by permethrin.

Treatment principles and treatments for pubic lice
Treatment principles and treatments for pubic lice


The main modern drugs for the fight against pubic lice presented in the domestic pharmaceutical market are shown in the table:

Insecticide group Active substance Release form Commercial name Organic phosphates Malathion Emulsion, gel Pedilin Pyrethrins Pyrethrin Spray can Spray Pax Permethrin Solution Nittifor Permethrin Cream Nyx Permethrin Emulsion Medifox Fenotrin Liquid soap Anti-bit

If the dosage form contains only one active ingredient, then there is a need to re-treat the infected surfaces 7-10 days after the initial disinsection. Such drugs are called monocomponent, and they include the following funds:

  • Pedilin;
  • Nittifor;
  • Nyx;
  • Medifox;
  • Anti-bit.

An easier to use and more effective dosage form against pubic lice is characterized by a combination of an active ingredient and a substance that prolongs the action of the main component. Such drugs are combined and include Spray-Pax aerosol, which is produced by the French pharmaceutical company Pharmygiene-SCAT. When using combined drugs against pubic lice, a single treatment is sufficient.

10 curious facts about the life of pubic lice

  • Archaeologists confirm that 10% of the population harbors 70% of parasites. Pubic lice are found in human remains that are more than 10,000 years old. Archaeologists do not meet them often, since from time immemorial there was a ritual of washing the body before burial;
  • of all human parasites, the pubic louse is considered a relatively harmless guest of our body, unlike other lice, it has not been caught in the transmission of any other infections;
  • very interesting statistics are how widespread pubic lice are in the world. It is believed that in the global population, every 50th adult is infected with pubic lice. Out of 100 sexually active men and women, 2-4 are infected with pubic lice. In countries with low levels of hygiene, there are many more infected;
  • pubic lice are used in forensic science to solve crimes. In their ventricles, you can find blood and DNA from different people who have had close contact;
  • among travelers returning from tropical countries and visiting doctors, in 1.6% of cases, pubic lice are found;
  • pubic lice often cohabit with other types of lice, in 7% of cases with head lice and in 9% of cases with clothes;
  • in 30% of those infected with pubic lice, other sexually transmitted diseases are found: HIV infection, syphilis, gonorrhea, chlamydia, genital warts and genital herpes;
  • even in the most developed countries (according to UK clinics), pubic lice are found in 3.5-1.7% of men and 2% -1.1% of women;
  • women who provide sexual services have pubic lice in 4.6%;
  • there is a worldwide increase in the resistance of pubic lice to drugs - insecticides
10 curious facts about the life of pubic lice
10 curious facts about the life of pubic lice

Pubic lice myths

One interesting study from college students in the UK demonstrates the common misconceptions about pubic lice as well as possible.

Myth one: a tumor of the genitals and temperature are signs of pubic lice

1.345% of students (girls and boys aged 17-23) reported their personal acquaintance with pubic lice. Young men have had this experience more often.

Of the symptoms of pubic lice, only 2 out of 817 students correctly indicated itching and the detection of insects and their nits, while most young people mistakenly believed that edema of the genitals and temperature were symptoms of pubic lice.

No one knew about the symptom of purple bruises at the site of the bites.

Myth two: you can get pubic lice in a public toilet

All young people naively believed that one could get infected in the toilet or while wearing someone else's underwear. This is a big misconception, pubic lice are transmitted by close contact of two bodies (skin to skin), since they are inactive and rarely leave their home on the host's body. The likelihood of infection through household items is extremely small.

Myth three: you can be treated with hormonal ointments, antibiotics, and even bleach with lysol

80% of students naively believe that antibiotics save from pubic lice, and some suggest that it is possible to kill pubic lice by washing the genitals with a solution of chlorine or lysol.

Lysol and chlorine are highly toxic substances with an irritating effect; if they get into high concentrations on the skin and eyes, even tissue death and general poisoning are possible!

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