What is scabies?
Scabies is a skin disease caused by parasitic scabies mites. The mite that causes scabies is Sarcoptes scabiei. These mites get themself burrowed into the skin and cause severe itching. Scabies can get transmitted through skin-to-skin contact, especially for those who live closely.
The itching feeling can get worse at night and causes major discomfort. According to NCBI, the estimated population for scabies is about 300 million infected individuals per year and most common among children and young adults. Additionally, scabies is highly prevalent in the geographic areas of
- South America
- Africa
- Southeast Asia and
- Australia
Scabies can also affect animals. However, the mites that affect animals will not be able to adapt to human skin.
The morbidity of the disease increases majorly due to the presence of secondary complications like post-streptococcal glomerulonephritis, lymphadenopathy and abscesses.
Who gets scabies?
Scabies can affect anyone of any age. People who live in overpopulated areas are at an increased risk of getting infected with the disease. Scabies can easily spread to infants and children who live with an infected person.
Elderly people who are bedridden and living in nursing homes can also get infected with scabies.
Prolonged contact, like sexual contact with an infected person, can also spread the disease. In rare cases, scabies can spread when a healthy person shares their clothing, bedding and towels with the infected person.
The incubation period of scabies is estimated to be about 8 weeks after the initial infection.
Scabies mites
Scabies is caused by a mite, Sarcoptes scabiei var. hominis. It is classified under the arthropods class Arachnida, and it is a human itch mite. These mites borrow themself in the upper layer of the skin called the epidermis. They can never reach below the stratum corneum.
These mite burrows appear as serpentine lines that are skin coloured or greyish. They are usually a centimetre in length.
There are other organisms of mites that infect cats, dogs, horses and pigs. These organisms can infect humans with limited pathogenicity. They cause temporary itching and cannot multiply on human hosts.
How does scabies spread?
Scabies usually spreads when there is prolonged skin-to-skin contact with an infected person. When a person has crusted scabies, it can spread when items like clothes and towels are shared.
In most cases, scabies will not spread through swimming pools. It is very rare that mites spread through wet conditions. Scabies will not be able to survive without a human host for more than 2-3 days.
A person with crusted scabies is considered to be highly infectious. When a person has crusted scabies, the level of infection through sharing things is also high.
The mites, when they infect humans, borrow themself in the epidermis, and they star laying eggs. These eggs develop into larvae, nymphs and then adults. These mites again lay eggs and the cycle of infection continues.
Where do scabies mites survive in the body?
The scabies mites invade the human skin and hide under the epidermis, and cause severe itching. The common sites where scabies mites hide are listed below.
- Bends and folds near your wrist and knee.
- Areas around the waist.
- Beneath fingernails.
- Around the nipples.
- Folds near the genitals and thighs.
These mites will not go deep under the skin. The rashes caused by scabies usually spread throughout the body and cause infections. These can lead to crusted forms where the person is highly contagious.
Different types of scabies
There are different types of scabies. The types are listed below.
- Crusted (Norwegian)
- Nodular
- Bullous
- Scalp
The crusted scabies is highly contagious and commonly occurs in people with weakened immunity.
Classic scabies usually contains about 10-15 mites, whereas people infected with crusted mites might have millions of mites covered under the skin.
The nodular type is common in children. They will be visible as brown-red nodules even after the mite's infection has been cleared.
The bullous is commonly seen in adults and often mistaken with another condition called bullous pemphigoid. Bullous pemphigoid is a skin condition that affects elderly people and causes raised rashes and itchiness. Large blisters also can be seen as the condition develops.
The scalp type of scabies usually resembles psoriasis. However, this type does not represent any symptoms.
Symptoms
The common symptoms of scabies usually represent itchiness and red bumps. There will be tiny spots when there is an infestation of scabies mites.
The adult female lays eggs, and the eggs hatch after 3-4 days. These young mites develop into adults after one or two weeks. The infected person becomes allergic to the mite protein, which leads to rash and itches.
The spread of rash is common in the initial stages of infection. The spread is noted to be very slow, and it takes from months to weeks for spreading. The other common symptoms of scabies are
- Itching that usually intensifies at night. This can lead to disrupted sleep.
- Raised bumps that become infected because of intense scratching.
- The rash that appears as grey or skin-coloured lines on the skin.
- Children affected with scabies will not be able to sleep due to severe itching.
- Vesicles around the finger webs.
- Inflammatory scabies can represent themselves as nodules in the genitals of males.
Diagnosis
The initial diagnosis of scabies will be a physical examination. The healthcare professional will closely examine any symptoms of mites in your skin. If required, a skin sample will be collected and viewed under the microscope to confirm the presence of the mites and also the presence of mites’ eggs.
The burrow of mites will be carefully removed with the help of a needle, or skin scrapings will also be removed. However, even if the presence of mite eggs is not found, a person may be infected with scabies.
Treatment
The initial treatment for scabies includes topical application of creams. According to WHO, topical application ointment should contain the following.
Permethrin 5%
Malathion in aqueous base 0.5%
Benzyl benzoate emulsion 10-25%
Additionally, oral administration of ivermectin has been effective and has been approved by most countries. However, the use of ivermectin in children and pregnant women is still not clear, and further research is required.
WHO also states that for people with scabies treatment, the itching usually intensifies, and doctors should make them aware of it.
The topical application of creams for children and infants should be applied from the head to all parts of the body. The cream will also be suggested to close contact with the infected person. The cream should be washed off after the recommended time. The other people in the household are also treated to avoid reinfestation.
Even after treatment for two weeks, the itching does not stop, and the rash is still visible; re-treatment will be required. Also, consult your healthcare professional for further assistance.
Risk factors of scabies
The primary risk factor for scabies is a person who lives in overcrowded areas. If a family has an infected person, the infection can easily spread from the infected person to others.
In adults, scabies easily spreads through sexual contact. It can be acquired from your sexual partner.
Scabies is a common disease and can infect any person of any age. The transmission of scabies is also highly contagious. Child-care facilities can harbour these kinds of diseases. Poor hygiene can also play a major role in the transmission of scabies.
People with weakened immunity and infected with HIV or cancer, and undergoing chemotherapy are vulnerable to scabies.
Conclusion
Scabies is a common disease and can occur to anyone. Self-hygiene can play a major role in the infestation of the disease. Additionally, people who work at healthcare centres are prone to the disease.
If you have severe itchiness that causes sleep disturbances, consult your doctor immediately. Scabies can be treated, and proper treatment is required to avoid reinfestation of the disease.
FAQs
Which is the most severe form of scabies?
What are the 5 symptoms of scabies?
The common symptoms of scabies include
1 Itching, especially at night
2 Rashes
3 Red bumps
4 Crust formation that can lead to further infection
