Scabies | Your complete guide to diagnosis, treatment, and management

Updated: Feb 3

Scabies are generally spread by prolonged skin-to-skin contact or skin-to-infested surface contact. It is highly contagious. It is difficult to say how long this contact needs to be without precise data to support it. However, in my practice after seeing hundreds of cases of scabies over the past two decades, the majority are from spending hours not minutes with a person or a location that is infested. Read more...

Topics

What are scabies?
How are scabies spread?
What are the symptoms associated with scabies?
How are scabies diagnosed?
How can scabies be treated?
How is it best to treat the home for scabies?
Can scabies spread disease?
How do I know if I successfully treated scabies?

Photo: Wix

Disclaimer: This page contains affiliate links to products. We may receive a commission for purchases made through these links.

What are scabies?

The term “scabies” is applied to the infestation of human skin with a mite, Sarcoptes scabiei var. Hominis. The mite enters the superficial layers of skin called the stratum corneum and lays its eggs to continue its life cycle.

How are scabies spread?

Scabies are generally spread by prolonged skin-to-skin contact or skin-to-infested surface contact. It is highly contagious. It is difficult to say how long this contact needs to be without precise data to support it. However, in my practice after seeing hundreds of cases of scabies over the past two decades, the majority are from spending hours not minutes with a person or a location that is infested. I have not come across a case linked to shaking hands or hugging someone. I have come across cases in dormitories where there is prolonged contact with a chair or couch in an affected individual’s room for over an hour. Scabies are generally not spread through pets or swimming pools.

Video: Techei

What are the symptoms associated with scabies?

In the first few days, you may not experience symptoms. Perhaps a little itchiness at the point of contact but nothing that most would take notice of. Often there is a delay of days and even 4 to 8 weeks before the intense itching sets in. Scabies tend to cause reddish intensely itchy bumps that can become scabby, scaly, and crusty and often form linear burrows as it tracks across the skin.

How are scabies diagnosed?

The vast majority of cases of scabies I diagnose clinically as it has a classic clinical appearance and presentation. The individual will be intensely itchy, developing scabs and crusted papules, worsening over time, and not obtaining relief from routine anti-itch measures. They have often been to a primary care physician or urgent care before seeing me and already received a course of steroids with no relief.

Scabies can be confirmed through skin scrapings and biopsies when unclear, however, the yield of these diagnostic tests can be low in the first few months of an infestation given the challenges in isolating a mite or finding evidence of mite presence such as mite feces or eggs.

How can scabies be treated?

Treatment for scabies requires a multipronged approach. Although scabies in individuals can be treated, the reality is that if we do not consider the environment and others in close contact with the individual diagnosed with scabies, there is a better chance than not that a reinfestation will occur.

I break down treatment to my patients as the following:

Patient treatment. We can treat the individual with scabies with one or a combination of methods. The oral Ivermectin can kill both the live scabies as well as the eggs of the scabietic mites. This treatment tends to be well-tolerated and reliable. Topical therapy with permethrin cream, lindane lotion, or spinosad suspension can be used to supplement therapy or on their own to treat the mites. Permethrin cream can only kill the live scabietic mites and not the eggs. It needs to have a repeat treatment in one week to kill the mites before they can lay eggs again recognizing the life cycle of the mite. Lindane lotion may require more applications. Spinosad suspension has better efficacy than the other topicals with just one treatment.
Household and close contact treatment. I highly recommend having all close contacts and household members also evaluated to treat for scabies or prevention of scabies even if they do not manifest symptoms. State laws may vary in terms of the ability of a physician to prescribe treatment in these circumstances for family members without being seen. To make the treatment effective and reduce the need for repeat treatment, it is advisable to have all family members and close contacts seen and evaluated to prescribe treatment and permit for observation afterward.
Treating the home. See below for a detailed explanation.

How is it best to treat the home for scabies?

In some ways, treating the home for scabies can be a little less daunting than other infestations. The first thing to bear in mind in approaching this process is scabies cannot live off of a human host for longer than 72 hours. Practically speaking, this means that any item or location that has not been in contact with your skin for 3 days is no longer a likely source of spread. With this in mind, the practical approach I recommend to my patients is to tackle this process with a coordinated effort.

Everyone should be treated simultaneously. Designate the day and time to start treatment and do this together. This will avoid mismatches that can result in inadvertent spread or re-exposure. Most of my patients find this simplest to do over a weekend.
Once treated, you are either not contagious or far less contagious within 24 hours. Whichever bedsheets you slept in overnight after treatment, put these through the laundry. Reuse these until you can be sure the treatment course is complete.
Leave all bedsheets and towels that have not been used most recently in the linen closet and all clothing items in the closet for at least 72 hours. If there are scabies present, they should not be able to survive after this point making it less necessary to actively launder.
Designate areas to spend your time in your home for 72 hours to permit areas with scabies present to dissipate the mites. Focus on using chairs that can be wiped easily and avoid upholstered furniture for this window of time.
Don’t forget that your car can be a source of spread. If you can avoid entering it for 72 hours, this is ideal. If seats can be wiped down, wipe them down. If they cannot, then

One study demonstrated that topical antiseptics such as hand sanitizers do not stop the spread of scabies. This also makes it challenging to understand which disinfectants can be effective against scabies. Even bleach does not directly list scabies as one of its activities. Scabies is susceptible to anti-mite approaches and is thought to not be able to survive temperatures over 50 degrees Celsius or 122 degrees Fahrenheit.

Can scabies spread disease?

Scabies only live in the most superficial layers of the epidermis. There is no vascular supply to this region. Through the process of itching, bacteria can be introduced into the skin from the environment but scabies itself is not known to transmit blood-borne pathogens.

How do I know if I successfully treated scabies?

Close monitoring with your Dermatologist is very helpful. It is true that you will stay persistently itchy or what I refer to as having a case of the “heebie-jeebies” for about 2 to 4 weeks. The hypersensitivity of the skin gradually declines over a month indicating successful therapeutic intervention. It is important to not feel overly anxious about the persistent sensation of itch for a few weeks as this is natural and referred to as a “Post Scabetic Hypersensitivity”.