Scabies is an infestation by a mite: Sarcoptes scabiei. The mite is normally not visible to the naked eye as it measures less than 0.5 mm in size.
Some drawings and other evidence discovered in Egypt indicate that the disease is old. Aristotle has also talked about “lice” escaping from small pimples if pricked.
However, lice do not cause scabies; an 8-legged mite resembling a louse is responsible.
What are the symptoms of scabies?
Some characteristic symptoms may indicate scabies infestation in a person:
- Itching that occurs especially during the night and is so intense that it doesn’t let a person go to sleep and
- Burrows are commonly seen in the skin between the fingers and toes.
A papule at the end of a burrow between the fingers
In addition, the burrows, along with a rash, can be present over other sites. These include wrists, skin folds of buttocks, armpits, groin, or breasts.
The rash caused by scabies is commonly present as papules (Small, red bumps present over the skin). Sometimes the infection may cause fluid-filled blisters instead.
Scabies rash is not caused by the mite itself
The mite causes scabies, but the rash is not directly due to the damage caused by the mite.
Instead, it is due to the hypersensitivity of our body against the mite.
Hypersensitivity is an indirect response to the presence of mites, feces, or eggs laid over the skin.
Usually, it takes 1-2 months from the time the mite is present on the skin till it starts causing symptoms if there has been no previous history of scabies infection.
However, subsequent infections cause symptoms in only about 1-2 days if the body is already sensitized to the scabies mite due to previous infestations.
Scabies mite lives on the skin!
Only a few scabies mites live normally on human skin, whereas a person diagnosed with scabies usually has 10-15 mites living on it.
Crusted or Norwegian scabies affect people with defective immune systems. It is a severe form of scabies, which can have millions of mites present at a time on the skin.
The adult mite lives off dead skin cells and burrows through the skin. The female mite then lays eggs inside these burrows. Subsequently, the eggs hatch, larvae come out and mature into adults, and the cycle repeats.
The mites, therefore, keep multiplying, creating burrows, irritating the immune system, and causing more skin lesions and itching.
How is the infection transmitted and diagnosed?
The infection is transmitted by direct skin-to-skin contact, usually among family members, or sexual contact with an infected person. The skin contact must be for at least 15-20 minutes to transmit the infection.
Your doctor diagnoses Scabies based on clinical history and the presence of skin lesions in a person, and similar complaints in other family members/contacts.
Usually, no additional investigations are needed for the diagnosis. However, scabies mites are visible after taking and examining the skin scrapings under a microscope.
How is scabies infection treated?
Since scabies mite causes infection, the goal is to kill the mite in an infected person and their contacts.
Permethrin lotion, applied one time over the body during the night and kept for over 6-8 hours, is usually prescribed by your doctor. It is neurotoxic and paralyzing for the scabies mites, which eventually die.
How to apply Permethrin
- Apply the lotion “all over the body” below the neck, especially between fingers, toes, and under the nails.
- Don’t forget to apply the lotion on the face and scalp of a child since these areas might also be infected.
- Avoid sensitive areas like the eyes, nose, and mouth.
- Wash off the solution the next day.
- A one-time application is enough to get rid of the infection. However, since the drug does not act on the unhatched eggs, it is necessary to repeat the application after a week or two to kill whatever new mites hatch out of those eggs.
- Avoid any physical contact with other individuals until the treatment is completed.
- Wash and change all your clothes every day along with the treatment.
- Since the scabies mite can live on furniture or bedding for 1-2 days, you must also wash your bedsheets and linens.”
Other treatment options
Permethrin lotion is most commonly prescribed for application, but oral medication like Ivermectin is sometimes preferred.
- Other medications acting against mites, like Crotamiton and Lindane, are not prescribed often.
- Along with the medications that kill mites, drugs for relief of itching or treating secondary bacterial infections are also prescribed.
- It takes a few days for the itching to go away even after killing the mites, and sometimes itching may persist for some weeks.
- Some people believe that taking foods like walnuts, rhubarb, or garlic in the diet can act as an insect repellant, thus helping eliminate the mite. However, don’t rely too much on this information as there is no scientific evidence for the role of diet in scabies.
