What cause crabs: Causes of crabs (pubic lice)

21.07.202317.06.2023 by alexxlab

Causes of crabs (pubic lice)

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By Dr. Ananya Mandal, MDReviewed by April Cashin-Garbutt, MA (Editor)

Crabs or pubic lice, contrary to common belief, are not caused by only poor personal hygiene. They may be transmitted to a healthy and clean person through close contact with an infected person. The lice crawl from the hair of one person to the hair of another person. These lice are unable to fly or jump. 1-7

Causative organism and its life cycle

Pubic lice called Pthiris pubis are different from head louse. Adults are yellowish grey or tan and appear like crabs.

Pubic lice have six legs front legs are very large and look like the pincher claws of a crab. Their second and third pairs of legs have claw like ends that helps them hold on to the coarse hairs tightly.

The adult louse is around 2mm in length. Females are usually larger than males. The lice live for one to three months. The female louse in their lifetime may lay up to 300 eggs.

The female lays the eggs and attaches them with specially secreted glue or cementing material to the base of the hairs. The eggs appear whitish grey and are smaller than a pin head. The eggs hatch after 6 to 10 days.

The eggs develop into nymphs. These are immature lice that hatch from the nits. A nymph looks like an adult pubic louse but it is smaller. These take around two to three weeks to mature into adults. To live, a nymph must feed on human blood. They grow to adulthood within two to three weeks and may start their own reproductive cycle.

The pubic louse feeds on human blood. When not on a human body, pubic lice can live for up to 24 hours. They rarely leave the human body except for moving onto another person. These lice live on thick coarse hairs like the pubic hair.

These lice may also live on other body hair like those around the anus, underarms, beard, moustache, chest, abdomen, and, rarely eyebrows and even eyelashes.

They are never found on hair over the scalp since this hair is thinner, softer and finer in comparison to body hair. Pubic lice are different from head lice (called Pediculus humanus capitis). Pubic lice do not live on other animals.

Mode of transmission of the pubic lice

Pubic lice are most commonly passed on through close contact with an infected person. This may be sexual contact as well. Unprotected vaginal, oral or anal sex may transmit the infection from an affected person.

Condoms and other barrier contraception cannot prevent transmission of the lice since these live on the pubic hairs.

Kissing a person whose beard is infested with the lice or hugging them may also spread the lice from person to person. Both men and women can catch them and transmit these lice.

Although rare, pubic lice may also spread by sharing bed linen, clothing, towels, toilet seats etc. with an infected person. This mode of transmission is rare since the lice seldom leave the human they are primarily living to live on an inanimate object like clothing for even and short period of time.

Spread through a shared toilet seat is also extremely rare since the lice cannot live long away from a warm human body and their feet are unable to walk on smooth surfaces such as toilet seats.

Sources

http://www.nhs.uk/Conditions/pubic-lice/Pages/Causes.aspx
https://www.bbc.com/
http://www.patient.co.uk/health/Pubic-Lice.htm
http://www.cdc.gov/lice/pubic/factsheet.html
www.brown.edu/Student_Services/Health_Services/docs/Pubic_Lice.pdf
https://www.unh.edu/
https://www.tn.gov/

Pubic Lice (Crabs) (for Teens)

What Are Pubic Lice (Crabs)?

Pubic lice are tiny insects (about the size of a pinhead). They usually live in hair in the pubic area (the area near the genitals). They also can live in the eyelashes, eyebrows, beard, armpit, and other body hair.

Pubic lice usually spread through sex. Less often, pubic lice is spread by touching infested clothing, towels, and bedding.

Pubic lice are also called “crabs” because of the tiny claws they use to cling to hair.

What Are the Signs & Symptoms of Pubic Lice?

Pubic lice usually cause itchiness. This can get worse at night when the lice become active.

Sometimes, lice bites can lead to skin redness and irritation. Lice in the eyelashes or eyebrows can cause eye itchiness and redness.

How Do People Get Pubic Lice?

Most people with pubic lice got them through sex or close sexual contact.

Less often, someone can get pubic lice from sharing clothes, sheets, or towels with someone who has pubic lice.

Lice can’t jump from person to person. It is very unlikely that someone would get pubic lice from a toilet seat. Lice can’t live away from a warm body for long and they do not have feet that could hang on to a toilet seat.

How Are Pubic Lice Diagnosed?

A health care provider usually diagnoses pubic lice by looking at the insect or nits (the small white egg that clings to hair). If needed, the insect can be sent to a lab for identification.

Anyone diagnosed with pubic lice needs to tell:

recent sex partners
people who have shared bed sheets, clothes, or towels

They should check for pubic lice and get treated, if needed.

How Are Pubic Lice Treated?

Pubic lice are treated with medicine to kill the lice. It may be a cream, lotion, or shampoo. Some are available at drugstores without a prescription. Any nits in the pubic hair need to be removed. Some people use their fingers or a comb to remove them, while others shave their pubic hair. Shaving does not get rid of pubic lice, though. The person also needs to use the medicine.

Most treatments for pubic lice need to be used more than once. So it’s very important to follow the directions included with the medicine.

All clothes, towels, and sheets used by the person with pubic lice must be:

washed in hot water and dried in a hot drier or dry cleaned
or
put in a sealed plastic bag for 2 weeks

Can Pubic Lice Be Prevented?

Because pubic lice usually spread during sex, not having sex is the best way to avoid them. Condoms do not protect someone from pubic lice because the lice live outside of the area that condoms cover. Shaving pubic hair does not always prevent pubic lice.

Not sharing clothing, bedding, or towels also can help lower the risk of getting pubic lice.

What Else Should I Know?

If you are diagnosed with pubic lice, it is important to go to the doctor and get checked for other STDs (sexually transmitted diseases).

The best way to completely prevent STDs is to not have sex (vaginal, oral, anal). If you do decide to have sex, use a latex condom every time.

Reviewed by: Amy W. Anzilotti, MD

Date reviewed: January 2022

description, features, recipes and useful properties

Crabs (lat. Brachyra) are short-tailed crayfish, the appearance of which is characterized by strongly bulging eyes, a cephalothorax protected by a strong shell, and five pairs of limbs. Crabs live in all the seas of the planet, they are also found in fresh waters. Crab meat is a delicacy. The word “crab” was borrowed by Russian from Western European (Dutch krab, English crab, German krabbe). In German, the word “Krabbe” is consonant with the verb “krabbeln” – “swarming, floundering.”

History of appearance

Crabs are ancient inhabitants of our planet. They appeared on Earth more than 180 million years ago and settled in the seas throughout its territory. People have used crab meat since ancient times. In Chinese written sources, there is evidence that the first crabs caught near the Yangtze River were eaten several thousand years ago. In England, books with recipes for dishes from this product dated back to the 17th century were found. Crabs are not only harvested in the wild, but also bred artificially. The first crab farms in Russia appeared in the Barents Sea in the middle of the 20th century. Currently, crab meat dishes can be enjoyed in many catering establishments.

Benefits and harms

Crab meat can be considered a dietary product. It does not harm the figure, does not increase blood sugar levels. Meat is rich in protein and iodine. The product also contains vitamins of group B, vitamins A, C and PP, macro- and microelements such as magnesium, calcium, potassium, sodium, phosphorus and iron. Eating crab meat strengthens the nervous, musculoskeletal and cardiovascular systems, and contributes to the normal functioning of the thyroid gland. When introducing crab meat into the diet, one should be careful and observe the measure: the product can cause allergic reactions. Fishing for crabs in polluted waters and improper harvesting of crabs can make the meat toxic, so you should only purchase the product from trusted manufacturers.

What does crab taste like

Crab meat has a soft, delicate, refined taste, which allows it to be combined with many other products. The taste of meat varies depending on which part of the crustacean this or that piece is taken from.

As it is

Crab meat is cooked or preserved. It is used in salads, soups, for making sauces. In East Asian and European cuisine, there are many recipes using this delicacy. The product is also actively used for decorating dishes. Meat goes well with eggs, parsley, tomatoes, mayonnaise and lemon juice.

How and how long to store

Store-bought frozen crab meat should be stored at -24 degrees. In vacuum packaging that retains its integrity, the product retains its properties for 6 months.

Curious facts

Since October 2016, the annual Hold the Crab festival has been held in the Far East of Russia, which attracts many tourists from all regions of our country.
Crab meat goes well with many foods. But there are also those whose “neighborhood” is considered undesirable. These are eggplants, pears and tangerines.

The roar of the ships broke the crabs’ defenses.

Man-made noise inhibits the ability of coastal crabs to color-camouflage and causes them to react more slowly to a threat. The main source of such noise at sea is ship propellers, while loud natural noise turned out to be practically harmless. The experimental results are published in Current Biology.

With the development of shipping in the ocean, the level of human-generated noise is gradually increasing. It is estimated that since the middle of the 20th century, it has been growing by about three decibels per decade and negatively affects marine animals. It is already known to cause alarm in humpback whales, and scientists also fear for mammal populations in the Arctic. Research in this area has focused mainly on vertebrates, but the impact of noise on arthropods and molluscs could potentially be just as significant.

The European shore crab can change the color of its shell depending on the environment, like octopuses and chameleons. True, unlike them, it takes not seconds, but hours and weeks to change color, but this is enough to protect against predators when living in a relatively homogeneous landscape.

Emily Carter and her colleagues at the University of Exeter have found that this adaptive camouflage ability is overwhelmed by ship engine noise. Scientists selected a group of dark crabs, divided them into three groups and settled them on an artificial white bottom, but under different conditions. In the pool of one of the three groups, the recorded noise of the propellers was played, and for the other two, the natural background of the sea was reproduced through the speakers, but for one of them it was amplified to the volume of the rumble of ships. Eight weeks later, the result was clearly noticeable: anthropogenic noise almost completely suppressed the change in pigmentation, while the natural background increased in volume had almost no effect.

Scientists attribute this to the fact that the sound background, which is different from the natural one, causes stress in crabs. The fact is that color change is a very energy-intensive process that requires a large amount of nutrients, which are not enough during stress.

In addition, the sounds of ships greatly suppressed the protective instincts. When attacked by a predator, any healthy crab tends to run away, but when simulating a bird attack on each of the three groups, it turned out that crabs living in conditions of anthropogenic noise react much more slowly to the threat, some individuals practically did not run away at all. The researchers note that the problem is not that the crabs have become deaf – in general they perceive sound, but when protecting they are guided by other senses. Stress is also to blame for poor and late decision making. The exact reason for such a different perception of noise remains to be known, this may be due to both the frequency of the sound and its character.