Examination findings include serpiginous white lines indicating mite burrowing. Common sites of mite burrowing include intertriginous areas, axillae, umbilicus, between digits, the beltline, nipples, buttocks, areolae of female breasts, flexural surfaces of the wrists or on the penile shaft. Type IV hypersensitivity reactions to the mite, eggs, or excrement may occur, forming erythematous papules. The itching associated with scabies gives way to scratching, encrustation, and possible impetiginization [6][4].

Secondary bacterial infections commonly occur following tunneling by the mites. Impetigo is especially common since a synergistic relationship between the scabies mite and Streptococcus pyogenes bacteria exists. Burrowing mites release complement inhibiting proteins that prevent the opsonization of S. pyogenes, which allows the bacteria to proliferate and evade the immune system [1].

Not all individuals exhibit classic manifestations of scabies infestations, which can make the infection challenging to diagnose. Patients may only have subtle signs and may not demonstrate the typical clues, which include a history of exposure, severe pruritis at night, or close contacts with a similar presentation [6].   Pruritis among several family members or close contacts should always cause the provider to think of scabies.  

Scabies is classically diagnosed by visulization of the rash as well as patient history.

Scabies can be diagnosed by visualizing mites in skin scrapings in the stratum corneum [6][3]. This method often misses the correct diagnosis because of the high chance of sampling error.

Other methods, such as the non-invasive  videodermatoscopy, can be utilized during the physical examination [2].  This technique has not yet become mainstream throught the Dermatology community. Videodermatoscopy uses a video camera connected to digital systems and equipped with optic fibers, lenses with up to 1000x magnification, and a light source or immersion liquid.   This technique is not available in the vast majority of offices in the United States.  Videodermatoscopy allows the inspection of the skin surface up to the superficial dermis and thus can identify burrows, mites, eggs, larvae, and feces. When compared to traditional skin scrapings, videodermatoscopy has several advantages. First, its noninvasive nature is better accepted by children, sensitive patients, and those who may refuse skin scrapings. It is also easy and quick to perform in comparison to the traditional microscope method. Moreover, the noninvasive technique minimizes the risk of accidental infections from blood-transmissible agents such as human immunodeficiency virus (HIV) or hepatitis C virus (HCV). Videodermatoscopy also is useful in evaluating patients to follow up after completion of therapy, demonstrating the presence of viable mites in cases of persistent infection or unsuccessful treatment [2].  Videodermatoscopy is seldom used in clinical practice currently.

Dermoscopy, also called dermatoscopy, is similar to videodermatoscopy but is handheld and does not require connection to a computer.  Dermoscopy is now commonly used in most Dermatology offices in the United States.  Dermoscopy has a lens with up to 10x magnification. With a dermatoscope, it is  possible to observe the burrow structure in scabies, also known as the "jetliner trail."  The burrows are also poorly visualized in dark skin or hairy areas. 

If the diagnosis is ambiguous, a skin biopsy can be used to confirm the diagnosis. In addition to biopsy, a newly developed serologic test can aid in the diagnosis of scabies [6].  Currently, this test is not commonly used in the United States. 

There are various treatments available for scabies. Evidence shows that when medications are used as directed, the efficacy of standard treatment options is comparable. These include topical permethrin, topical crotamiton, and systemic ivermectin. Adverse reactions are rare to these medications [7].

Topical permethrin 5% cream is effective and widely used. The cream is typically applied once a week for two weeks (total of 2 treatments). However, this treatment is occasionally associated with scabies resistance, poor patient compliance, and rare allergic reactions [6]. 

Oral ivermectin is another option, although the United States Food and Drug Administration has not approved its use for scabies treatment. It is administered to individuals ten years and older and given one time. An additional dose is given two weeks later if symptoms persist. Two doses of ivermectin are scabistatic; the second treatment kills mites that have hatched since the first treatment. Oral ivermectin is recommended due to convenience, ease of administration, favorable side effect profile, and safety. Rates of compliance are higher with this treatment modality than with topical permethrin, and the tablet form of ivermectin reduces the likelihood of misuse or inadequate application, as may occur with the topical permethrin [6]. Systemic ivermectin is superior to topical permethrin when treating scabies outbreaks. Ensuring adequate treatment is especially pertinent to the treatment of individuals living in close proximity, such as in homeless shelters, prisons, and healthcare facilities [7].

Other options are topical lindane, 5% precipitated sulfur, malathion, and topical ivermectin.

Treatment choices may be limited in those with S. scabiei resistance or with limitations due to cost, availability, or potential toxicity, especially among pregnant women and children.

Treatment failure / recurrence  is common, and isolating the cause can help prevent further infection and limit outbreaks in communities. Reasons for treatment failure include not treating close contacts simultaneously, not decontaminating beddings and clothes at the time of treatment, and nonadherence to the treatment regimen.  Treatment failure of crusted scabies can result from ivermectin-resistant Sarcoptes mites. Moxidectin is the recommended therapy for known ivermectin-resistance [4].

The clinical presentation of scabies may  resemble infections caused by other sources such as bacteria, fungi, parasites, and viruses [3]. Scabies often gets misdiagnosed as eczema, dermatitis prurigo nodularis, or lupus erythematosus [8].

Treating the patient along with close contacts and family members is associated with a good prognosis. With adequate treatment, patients can be expected to recover fully.

Without treatment, the infection can spread to other members of the community and cause an outbreak within the population.

Possible complications of a scabies infection include persistent itching, insomnia, secondary bacterial infection, and outbreaks of the disease to the community [6]. 

Scabies spreads quickly from person to person via regular skin contact or transmission via clothing or bed sheets. Management involves promptly treating infected persons and their close contacts and decontaminating bedding, towels, and clothing.

Isolation becomes crucial in crowded settings like hospitals, to stop the spread of infection. The bedding, towels, and clothing of the infected individual must be machine-washed in hot water (at least 75 degrees Celcius) and dried with hot air. Topical medication may be given to close contacts for prophylactic therapy [3][5].

Treatment failure is common, and isolating the cause can help prevent further infection and limit outbreaks in communities. 

Regardless of symptoms, all close contacts must receive treatment to prevent reinfection. Many states have legalized Expedited Partner Therapy, which allows physicians to write prescriptions for close contacts of a patient with scabies. This law applies if scabies is considered a sexually transmitted infection in that state. Patients and close contacts should also decontaminate beddings, towels, and clothing at the time that treatment is received [6]. 

Nonadherence to the treatment regimen is another cause of persistent infection. If topical permethrin cream is the chosen treatment option, it is to be applied to the entire body from the neck down in children and adults. In infants, the whole body, including the head, is treated with permethrin cream. The cream should be left on the body for 8 hours, rinsed off, and reapplied one week later. Permethrin is scabicidal, and the second treatment assures that any missed spots from the first treatment are covered in the second [6]. 

A common sequela that patients complain of is persistent itching after treatment, which may be attributable to treatment failure, misdiagnosis, or often cutaneous irritation. Other post-scabietic complaints include Id reaction also called auto-eczematization, and epidermal changes from topical treatments. Permethrin cream contains several potential allergens including formaldehyde, permethrin itself, and components of the cream base. Transient pruritis after treatment with oral ivermectin may occur and is due to the mass release of antigens following the destruction of the mites [6].

Scabies is spread easily through skin to skin contact. Contact precautions and isolation of hospitalized individuals are vital to protecting healthcare workers and other patients in a healthcare facility [3]. Management of scabies requires an interprofessional team approach. If an interprofessional team member suspects an infection with Sarcoptes scabiei, they should alert other team members so that steps can be taken to prevent the spread. 

Recognizing scabies infection and being able to diagnose this condition is crucial for patient care. One study showed that 45% of patients diagnosed with scabies, were actually suffering from other conditions such as eczema, papular dermatitis, irritant dermatitis, or contact dermatitis.

Education about scabies and its presentations is essential for all providers coordinating care, including primary care, emergency medicine, urgent care, pharmacy and even dermatology [6]. Pharmacists are aware of topical creams for scabies treatment and must be able to compound with other ingredients to effectively manage the infection and pruritis. Medication compliance should be encouraged because in most cases, failures are due to non-adherence to the treatment regimen. Nurses will likely be on the front-line for monitoring treatment adherence, providing further patient and family education, and determining other people who will need treatment. Finally, the nurse practitioner should educate the patient on how to eradicate scabies in the home; this is vital to ending the cycle of infestation.

Scabies is a significant problem in public health, and one common reason for treatment failure is non-adherence to the treatment regimen. Additionally, improvements in living conditions, avoidance of overcrowding, and avoidance of sharing personal care products can decrease the likelihood of persistence of this pest. While some individuals do obtain relief from symptoms, recurrences are frequent. The level of interprofessional collaboration outlined above is critical to treatment success and optimal outcomes. [Level 5]