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Scabies

Scabies is a common parasitic skin disease, which is caused by Sarcoptes scabiei.


Presentation

Clinical manifestations are pruritus that worsens during the night and a papular rash. The pruritus is a result of a delayed type-IV hypersensitivity reaction to the mite, the mite’s feces or their eggs [1]. Therefore symptoms may not appear until 4 to 6 weeks after infection.

During the incubation period, symptoms of scabies typically begin to present 3-6 weeks after the primary infection. In patients who have previously been infected by scabies, symptoms may appear earlier due to sensitization of the patient’s immune system.

During infestation period the lesion(s) are small, erythematous, nondescript papules, often excoriated and tipped with hemorrhagic crusts. The burrow is a thin, grayish, reddish or brownish line that is 2-15 mm long. Miniature wheals, vesicles, pustules, and rarely bullae may also be present.

The typical distribution of scabies is:

  • sides and within webs of fingers
  • flexor aspects of the wrists
  • extensor aspects of the elbows
  • anterior and posterior axillary folds
  • skin adjacent to nipples in women
  • periumbilical area
  • waist
  • male genitalia
  • extensor surface of knees
  • buttocks
  • adjacent thighs
  • lateral and posterior aspects of feet

Usually the back and head are not involved. Young children and infants often have involvement of the palms and soles and all aspects of the fingers. Lesions in children are usually more inflammatory than in adults and often vesicular or bullous.

Norwegian Crusted Scabies (scabies crustosa)

This subtype of scabies commonly occurs in immunocompromised patients. These result in thick crusts of skin that contain large numbers of scabies, mites and eggs. The mites in the crusts are not any more virulent as the ones in non-crusted scabies. However they are significantly more numerous (up to 2 million per patient). The fissures associated with crusted scabies provide a portal of entry for bacteria.

In an immunocompromised person, this may lead to impetigo, severe infection and even sepsis. Crusted scabies begin with poorly defined erythematous patches that quickly develop prominent scales. Scalp, hands and feet are commonly affected. Lesions are malodorous. Nails may become distorted and discolored, itching may be minimal or absent.

Treatment with oral ivermectin and topical permethrin has been successful. In very severe cases, surgical debridement in combination with the ivermectin and permethrin, has been shown to be an effective treatment.

Amyloidosis
  • Eventually a diagnosis of primary systemic amyloidosis was made after she developed frank lingual hypertrophy despite normal initial serum protein electrophoresis and negative abdominal fat pad aspiration.[ncbi.nlm.nih.gov]
Weight Loss
  • In households where crusted scabies is present, a diagnosis of parental neglect due to recurrent scabies and weight loss in children should be made with extreme caution.[ncbi.nlm.nih.gov]
Aspiration
  • Culture of blood sample and pus aspirate from the ankle and chest yielded a pure growth of Staphylococcus epidermidis.[ncbi.nlm.nih.gov]
  • Eventually a diagnosis of primary systemic amyloidosis was made after she developed frank lingual hypertrophy despite normal initial serum protein electrophoresis and negative abdominal fat pad aspiration.[ncbi.nlm.nih.gov]
Pruritus
  • Scabies is a common ectoparasitic disease that can be diagnosed based on the presence of pruritus and typical clinical signs including burrows, vesicles, and erythematous papules.[ncbi.nlm.nih.gov]
  • This case demonstrates an unusual presentation of primary systemic amyloidosis consisting of arthritis and intense debilitating pruritus without primary skin lesions for a full year prior to diagnosis of multiple myeloma.[ncbi.nlm.nih.gov]
  • Persons with crusted scabies may not show the usual signs and symptoms of scabies such as the characteristic rash or itching (pruritus).[cdc.gov]
  • Age   15 years, male sex, number of students in the school   500, no access to the school infirmary, sleeping with others, sharing beddings, clothes or toilet stuffs, pruritus in the close entourage and complaining of pruritus were significantly associated[ncbi.nlm.nih.gov]
Eczema
  • He was repeatedly diagnosed with eczema, but treatment failed to achieve efficacy. Interestingly, a microscopic examination of the lesions revealed numerous scabies mites and eggs. Thus, we confirmed the diagnosis of Norwegian scabies infection.[ncbi.nlm.nih.gov]
  • We report a patient treated for eczema with 9 months of progressive immunosuppression who was found to have crusted scabies. J Drugs Dermatol. 2018;17(10):1131-1133.[ncbi.nlm.nih.gov]
  • Cutaneous biopsies showed signs of subacute eczema. The eruption was treated with topical corticosteroids and emollient therapy. There was no other new drug administration or a history of irritants.[ncbi.nlm.nih.gov]
  • Scabies infestation should be considered when a recent onset of itching is associated with eczema and presence of burrows or comma-like papules at predilection sites.[ncbi.nlm.nih.gov]
  • Over time papules can change into vesicles and bullae. [ 12 ] Papules and vesicles frequently develop into excoriations, eczema exacerbations, secondary infections and crusts.[patient.info]
Eruptions
  • Subcorneal pustular dermatosis is characterized by numerous relapsing pustular eruptions on normal or mildly erythematous skin.[ncbi.nlm.nih.gov]
  • Mucosal drug eruption was suspected, and eruptions around the mouth and on the tongue resolved within 1 week after ivermectin being discontinued. 1% gamma-benzene hexachloride ointment was applied topically on the body from the neck down once a week,[ncbi.nlm.nih.gov]
  • We report a case of a 79-year-old man who developed a bullous pemphigoid-like eruption. He presented to our unit 4 months after the onset of symptoms. An autoimmune bullous disease was suspected.[ncbi.nlm.nih.gov]
  • Two months later, she had the onset of a new vesiculo-pustular eruption on the palms and soles, consistent with scabies infestation and treatment with topical permethrin 5% cream resulted in resolution of the entire eruption, including the primary nodule[ncbi.nlm.nih.gov]
  • […] scabies is a common infestation that usually presents as a pruriginous eruption consisting of erythematous papules, nodules, and excoriations. Diagnosis relies mostly on clinical features, including the identification of scabietic burrows.[ncbi.nlm.nih.gov]
Excoriation
  • Excoriated papules with honey-colored crusting were present on the abdomen, arms, and legs. Treatment for suppurative folliculitis and prurigo nodularis produced no improvement. A biopsy of the rash was performed. Patrick C. Carr, B.A. Robert T.[doi.org]
  • It manifests with pruritic erythematous papules and excoriations, in addition to the pathognomonic burrows. Multiple drugs can be used for treatment, but resistance to conventional therapy is increasing throughout the years.[ncbi.nlm.nih.gov]
  • We report the case of a 63-year-old woman with a history of undifferentiated connective-tissue disease, polyarthritis, and bilateral carpal tunnel syndrome who presented with generalized pruritus and erythematous and excoriated papules on the trunk and[ncbi.nlm.nih.gov]
  • […] scabies is a common infestation that usually presents as a pruriginous eruption consisting of erythematous papules, nodules, and excoriations. Diagnosis relies mostly on clinical features, including the identification of scabietic burrows.[ncbi.nlm.nih.gov]
  • Disseminated, excoriated, erythematous papules are usually seen on the anterior trunk and limbs. Crusted scabies occurs in immunocompromised hosts and may be associated with reduced or absent pruritus.[ncbi.nlm.nih.gov]
Pruritic Rash
  • A 61-year-old woman presented with a severe pruritic rash. Excoriated papules with honey-colored crusting were present on the abdomen, arms, and legs. Treatment for suppurative folliculitis and prurigo nodularis produced no improvement.[doi.org]
  • The most common symptoms are severe itching and pruritic rash with a characteristic distribution pattern on the body. What are scabies? Scabies is an infection caused by tiny mites that makes your skin very itchy.[symptoma.com]
  • Scabies is often confused with other pruritic rashes such as eczema, impetigo, tinea corporis (ringworm) and psoriasis. [3] For example, according to one study from Brazil, [9] 18% to 43% of children diagnosed with eczema actually had scabies.[cps.ca]
  • Clinical Cases Case 1 Clinical Atlas figs. 7-34 & 7-57 7-26 & 7-27 6-year-old male Attends elementary school; develops intensely pruritic rash on wrists, umbilicus, hands and feet No sick contacts Excoriated scaly papules clustered on the wrists/hands[dermquest.com]
  • Diagnosis The diagnosis of scabies can often be made clinically in patients with a pruritic rash and characteristic linear burrows.[emedicine.com]
Pruritus Vulvae
  • Micheline Moyal-Barracco, Pruritus Vulvae, Pruritus, 10.1007/978-3-319-33142-3_43, (329-342), (2016). Shu-Ling Chen, Kuei-Ling Chen, Li-Hung Lee and Cheng-I.[dx.doi.org]
Genital Lesions
  • It can take a month after treatment for the general itching to subside completely, and longer for the lumpy genital lesions to resolve. Your GP may recommend repeating the treatment or they may prescribe a different lotion.[nhsinform.scot]

Workup

The diagnosis of scabies is usually determined from the patient’s history and the distribution of the lesions. Affirmative answers that my indicate scabies include: Wide spread itching that is worse at night everywhere on the body but the head? Any pruritic eruptions with characteristic lesions and distributions? Are there any other household members with similar symptoms?

Tests

Skin scraping – Skin scraping may allow direct observation of the mites, eggs or the mite’s feces pellets. This involves placing a drop of mineral oil over the skin lesion and scraping the area with a number 15 blade or pinching the area between the thumb and index finger and while shaving the top layer of the skin. The specimen is then placed on a slide and visualized under a microscope at 10x power for mite eggs or mites [4]. Draw backs to this method are that special stains and equipment are required and children may not tolerate this well.

Dermoscopy – Dermoscopy may also allow direct observation of the mites or burrowing. This test involves an examination of the skin surface with a handheld dermatocsope which allows visualization of the dermal epidermis. The characteristic finding on dermoscopic examination is a dark, triangular shape that represents the mite’s head within a burrow, called the “delta wing” sign. The primary draw back to this method is the need to have specialized equipment and evaluation is more difficult in dark skinned patients.

Adhesive tape test – Transparent tape is firmly applied directly onto a lesion and then quickly removed. The tape is then applied to a glass and examined for mites and eggs. This test is most often used in c clinics because no special equipment is needed and children tend to tolerate this test better than skin scrapings.

Sarcoptes Scabiei
  • From Wikidata Jump to navigation Jump to search human disease Sarcoptic itch infestation by Sarcoptes scabiei infestation by Sarcoptes scabiei var hominis edit Language Label Description Also known as English scabies human disease Sarcoptic itch infestation[wikidata.org]
  • Convert to ICD-10-CM : 133.0 converts directly to: 2015/16 ICD-10-CM B86 Scabies Approximate Synonyms infestation by Sarcoptes scabiei var hominis Applies To Infestation by Sarcoptes scabiei Norwegian scabies Sarcoptic itch ICD-9-CM Volume 2 Index entries[icd9data.com]
  • BACKGROUND: Norwegian or crusted scabies is considered a rare affection and presumably represents an abnormal host immune response to Sarcoptes scabiei. As the condition mimics a range of dermatoses, it can be easily misdiagnosed and mismanaged.[ncbi.nlm.nih.gov]
  • Scabies is a common parasitic infection caused by the mite Sarcoptes Scabiei. About 300 million cases of scabies are reported annually.[ncbi.nlm.nih.gov]
Brugia Malayi
  • Ardelli, ABC transporters influence sensitivity of Brugia malayi to moxidectin and have potential roles in drug resistance, Experimental Parasitology, 10.1016/j.exppara.2011.06.018, 129, 2, (137-144), (2011). Dennis P.[doi.org]

Treatment

Complete eradication of mites is essential for treatment. The patient as well as his/her close contacts must be treated simultaneously.

Medications

Both oral (e.g. ivermectin, thiabendazole, flubendazole) and topical creams (e.g. lindane, permethrin, sulfur containing products, crotamiton, malathion, benzyl benzoate are used to treat scabies mites [5].

There is no international consensus on the treatment of scabies. However, 5% permethrin with oral ivermectin are usually the first line choices for treatment. Clinical trials evaluating the toxicity of various therapies have indicated that topical permethrin 5% cream and oral ivermectin are reasonable first-line therapies, with minimal side effects.

In another clinical trial evaluating the efficacy between 5% permethrin cream or 1% lindane lotion found similar cure rates achieved in 4 weeks after a single whole body application of each. However, permethrin has less neurotoxicity than lindane, particularly in children, and therefore is preferred [6].

Oral ivermectin is an anthelmintic with a half-life of 36 hours. The advantage to an oral medication compared to a topical medication is its ease of use; lack of treatment associated dermatitis and increased compliance. Ivermectin is first line therapy in nursing home or other institutional facilities where topical therapy may not be practical [7].

Randomized clinical trials have shown that a single dose of ivermectin 200 mcg/kg is as or more effective than application of 1% lindane, but LESS effective than a single application of permethrin. Two doses of ivermectin achieved equivalent cure rates to a single application of permethrin [8].

The CDC recommends using ivermectin (200 mcg/kg by mouth as a single dose with a repeat dose 2 weeks later) as an equivalent option to topical permethrin [9].

Itching can be controlled with antihistamines. Itching may persist up to 2 weeks after treatment because of hypersensitivity reaction to mites, mites feces and eggs. High potency topical corticosteroids can also be used to control itching after eradication of mites.

The entire household and close contacts must also be treated in addition to the patient at the same time to prevent re-infection or cross contamination. Fomite transfer of scabies may also occur although it is not as much of a concern as person to person transmission.

There is a possibility that contaminated clothing can result in spread or reinfection with scabies. Such items should be placed in a plastic bag for 3 days (scabies mites cannot survive for more than 2-3 days away from human skin). Then machine washed with hot water and placed in a hot dryer or dry cleaned [10].

Prognosis

Scabies is curable with scabicide medications.

Etiology

Scabies is caused by the host-specific mite Sarcopetes scabiei hominis, which is an obligate human parasite and a member of the family Sarcoptidae.

Epidemiology

Almost 300 million people may be infected worldwide. The scabiei mite depends on humans for survival and infection occurs from human to human contact.

It is equally seen in men and women and in persons of all races. It is most prevalent in crowded conditions such as nursing homes, child care facilities, extended-care facilities and prisons. 

Scabies is more prevalent during the winter than in the summer. This may be attributed to greater physical crowding in the winder and also because the mites can survive longer on fomites in colder temperatures [1].

Sex distribution
Age distribution

Pathophysiology

Mites can survive off a host for 24 or 36 hours depending on environmental conditions [2]. The mites mate on the surface of the skin and then the female burrows into the skin to lay the eggs. The eggs hatch a few days later and nymphs appear.

Burrowing is facilitated by secretion of enzymes which cause skin damage detectable at the microscopic level. The female mite burrows into the epidermis to the level of the granulosum and burrows down further about 2 mm a day, lays 10-25 eggs a day and then dies.

The larvae hatch in three to four days, leave the burrow for the surface of the skin, copulate and continue the cycle.

Prevention

There are no guidelines for prevention of Scabies.

Summary

Scabies is a parasitic infestation of the skin by the mite Sarcopetes scabiei. The female mite burrows into the epidermis and lays eggs.

The most common symptoms are severe itching and pruritic rash with a characteristic distribution pattern on the body.

Patient Information

What are scabies?

Scabies is an infection caused by tiny mites that makes your skin very itchy. This happens when tiny insects called mites burrow under your skin to lay eggs each day for several weeks.

How do you get scabies?

Scabies is spread from people to people that are in close contact (skin to skin contact) and through shared bedding, clothing, towels of the infested person.

What are the symptoms of scabies?

The common symptom is severe itching that is worse at night and small red bumps that may be hard to see. The itching is caused by allergic reaction to the mites. Therefore, the itching may start a few weeks after a person is infected. The body parts impacted the most by scabies are:

  • Between the fingers, in the web between fingers
  • Skin folds around wrists, elbows, knees, armpits
  • Around the waist
  • Around the penis and scrotum in men
  • Around the nipples in women
  • Around the lower buttocks and upper thighs
  • On the sides and bottom of feet

Treatment and Control

If you have these symptoms, you should see your doctor. He/she will give you a medicine to cure the scabies mites. If you keep scratching, you may get infections. You can use anti-histamines (allergy pills) to stop the itching while you are undergoing treatment. Itching may last 2 weeks after you finish your treatment.

Once your doctor starts you on the medication, he/she will also ask the people in close contact with you to start the treatment as well. This is because they may be carrying scabies, even without any symptoms. The goal is to prevent re-infection.

Wash all clothes that you and others wore in the last week in hot water and dry on high heat in the dryer. Also wash bedding, towels, stuffed animals, etc. Dry cleaning will also get rid of the mites. If you are not able to wash or dry clean these items, place them in a plastic bag for 3 days. The scabies mites cannot live away from the body for more than 2-3 days.

References

Article

  1. Chosidow O. Clinical practices. Scabies. N Engl J Med 2006; 354:1718.
  2. Green MS. Epidemiology of scabies. Epidemiology Reviews 1989;11:126-50.
  3. Maghrabi MM, Lum S, Joba AT, Meier MJ, Holmbeck RJ, Kennedy K. Norwegian crusted scabies: an unusual case presentation. J Foot Ankle Surgery 2014; 53: 62-6.
  4. Chouela E, Abeldano A, Pellerano G, Hernandez MI. Diagnosis and treatment of scabies. American Journal of Clinical Dermatology 2002;3(1):9-18
  5. Scheinfeld N. Controlling scabies in institutional settings: a review of medication, treatment models, and implementation. American Journal of Clinical Dermatology 2004;5(1):31-7.
  6. Schultz MW, Gomez M, Hansen RC, et al. Comparative study of 5% permethrin cream and 1% lindane otion for the treatment of scabies. Arch Dermatol 1990; 126:167.
  7. Madan V, Jaskiran K, Gupta U, Gupta DK. Oral ivermectin in scabies patients: a comparison with 1% tipical lindane lotion. J Dermatol 2001; 28:481.
  8. Usha V, Gopalakrishnan Nair TV. A comparative estudy of oral ivermectin and topical permethrin cream in the treatment of scabies. J Am Acad Dermatol 2000; 42:236.
  9. Workowski KA, Berman S, Centers of Disease control and Prevention (CDC). Sexually transmitted diseasesss treatment guidelines, 2010. MMWR Recomm Rep 2010; 59:1.
  10. Fitzgerald D, Grainger RJ, Reid A. Interventions for preventing the spread of infestation in close contracts of people with scabies. On line publication – Cochrane library collection.

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Last updated: 2019-07-11 22:52