Scabies is a highly contagious pruritic ectoparasitic infestation of skin mite Sarcoptes scabiei var. hominis. (Chouela et al., 2002; Currie and McCarthy, 2010) The scabies mite, an arachnid of the genus Acarus, was first identified by Bonomo in the year 1687 AD. The adult female is larger and responsible for reproduction of new eggs. Copulation occurs in small burrows excavated by the females. The burrows are usually not confined to the stratum corneum but are inclined downwards into the epidermis. The life cycle of the mite is 14 to 21 days. (‘Rook’s Textbook of Dermatology’, 2016)
Typical clinical presentation: Scabies can present in three distinct forms; common scabies, crusted scabies also known as Norwegian scabies, and nodular scabies. Common scabies has the classical presentation of nocturnal pruritus along with positive history of contacts. In crusted scabies patients present with thick crusted lesions on hands and feet, nail dystrophy, and eruptions with erythematous scaling with mild or absent pruritus. They usually harbor few hundreds to millions of mites and occur most frequently in patients with immunocompromised status. It is difficult to treat and highly contagious. Nodular scabies presents as nodules in flexural areas and is an allergic immune response to the feces of the scabies mite. (Heukelbach and Feldmeier, 2002; Chosidow, 2006)
Clinical presentation in nursing home residents and how it differs: In debilitated, immunocompromised, or institutionalized patients, scabies may present with some atypical features of absent pruritus, truncal papulosquamous dermatoses and absence to reporting symptoms because of dementia or vocal disabilities. Aging causes the loss of epidermal undulations and progressive flattening of the undersurface of the epidermis which enables the scabies mite to move at a faster rate and hence multiply at a faster rate causing quicker than anticipated spread of scabies in aging patients who are more likely to be institutionalized in nursing homes. The coexistence of cognitive or functional disability in the geriatric patients may impair the ability to scratch and thus prevent effective elimination of the mite and reporting of the disease to the facility staff. (Wilson, Philpott and Breer, 2001)
Diagnosis: Most of the scabies patients are diagnosed by clinical evaluation. Absolute confirmation can only be declared after visualizing live mite or burrows under the microscope. The presence of mites, eggs, fragments of egg shells or scybala confirms the diagnosis. Dermoscopy has been getting popular in recent years for diagnosing or detecting the mite without going through ink tests or actual microscopes. Under dermoscopy on 40x magnification a classical ‘jet‐with‐contrail’ can be seen, which is actually the mite. A skin biopsy may confirm the diagnosis of scabies if a mite or parts of mite come under the slice. Howver mostly nonspecific signs are usually seen e.g. papillary oedema, & superficial and deep perivascular inflammatory cell infiltrates with numerous eosinophils. It is ssential in cases of
crusted scabies or scabies in health care settings to have a confirmation of scabies so rest of the inhabitants and contacts can be treated.(‘Rook’s Textbook of Dermatology’, 2016) It is however very difficult to distinguish active infestation, residual skin reaction and reinfestation from each other.
Treatment: First line treatment is classical scabies include 5% permethrin solutions and/or oral ivermectin (200 mcg/kg). Second line agents include benzyl benzoate (10 or 25%), topical sulfur (6 to 33%), lindane and crotamiton. Permethrin is usually well tolerated however skin irritation can be a side effect. Use of lindane has fallen out of favor due to risk for systemic toxicity (e.g., seizures, and death in elderly and children). (Workowski, Bolan and for and Prevention, 2015; Salavastru et al., 2017) Crusted scabies however is mostly treated with a combination of two medications usually topical permethrin along with oral ivermectin. Antihistamines are given for relief of pruritus and topical mild potency steroids are given for post scabies eczema. General environmental preventive measures include laundering or sequestering items that came in close contact with the patients for example clothing with prolonged contact (>10 minutes) with the infested individual and adequate cleaning of rooms inhabited by patients with crusted scabies. Ivermectin is thought to potentiate GABA activity and drugs, such as barbiturates, benzodiazepines and valproic acid, which also enhance GABA activity, may increase its toxicity and should be avoided. Nursing home patients are usually on these medications.
Treatment of scabies in nursing home patients:
Rapid identification and treatment of scabies is integral part to minimize spread of the disease among other patients. Institutional infection-control personnel should be contacted immediately, and the patient should be isolated from other patients in the institution. Recommended general management measures following a diagnosis of scabies include:(Wilson, Philpott and Breer, 2001; Liang and Reno, 2015)
- Prompt involvement of institutional infection-control team.
- Isolation of the affected patient from other patients.
- Assignment of a dedicated care team for the patient to minimize exposure of staff, if possible.
- Strict contact precautions, including avoidance of direct skin-to-skin contact with the patient and use of protective gowns, gloves, and shoe covers, until the patient has been treated and a scabies preparation is negative.
- Frequent cleaning of the patient’s room to remove contaminated scales, eggs and crusts; thorough cleaning and vacuuming of the room after the patient is discharged from the room. Avoid using the same vacuum equipment in other rooms.
- Laundering of clothing and bedding with a washing machine and dryer utilizing hot water and hot dryer settings; utilization of protective clothing and gloves by laundry personnel.
- Treatment of all individuals (eg, staff, visitors, family members) who came in direct physical contact with the patient or clothing, bedding, or furniture.
- Avoidance of skin-to-skin contact with the patient until at least eight hours after treatment.
Treatment failures are common and under reported in institutional settings. Usually they happen because of inadequate application of scabicide, insufficient penetration of scabicide, reinfestation from untreated contacts and resistance of mites to scabicide (although rare).
Preventative measures in institutionalized settings:
The resident contacts should be notified of their potential exposure to scabies and visitors should be limited to the patient for some time. If it is imperative for the visitors to meet proper security clothing should be used. The outbreak must be reported to government authorities. New admission must be avoided if possible. If admissions are to be taken, then all new residents and staff should be screened and treated for skin conditions suggestive of possible scabies. Education and training must be provided to direct care staff employed by the institution, including but not limited to volunteers, private duty staff, laundry and housekeeping personnel. Proper teaching material including signboards must be displayed and literature provided to visitors and patients who are not debilitated. Adequate and accurate knowledge about scabies treatment and control will improve understanding, reduce anxiety, and facilitate outbreak control in the facility. (ACDCP, 2009)
Implications of scabies in institutionalized settings:
The diagnosis of scabies can be very hurtful for the patients’ health and name of the institution. Patient’s families can sue the institution if the patient dies because of scabies. There have been few cases in the USA where patients have died because a simple scabies case was missed by the staff and late the facility was sued for damages.
Although scabies is a very common disease in the dermatologic settings and prevalent in poor socioeconomic status communities but in the setting of institutionalized settings like nursing homes it can become a life-threatening disease if proper measures are not taken. Therefore, all the staff should be aware of common scabies symptoms and be able to report them to the physicians along with better understanding of the preventative measures discussed earlier.
- ACDCP, 2009, Scabies Prevention and Control Guidelines Acute and Sub-acute Care Facilities, Los Angeles County Department Of Public Health Acute Communicable Disease Control Program.
- Chosidow, O. (2006) ‘Scabies’, The New England Journal of Medicine, 354(16), pp. 1718–1727. doi: 10.1056/nejmcp052784.
- Chouela, E. et al. (2002) ‘Diagnosis and Treatment of Scabies’, American Journal of Clinical Dermatology, 3(1), pp. 9–18. doi: 10.2165/00128071-200203010-00002.
- Currie, B. J. and McCarthy, J. S. (2010) ‘Permethrin and Ivermectin for Scabies’, The New England Journal of Medicine, 362(8), pp. 717–725. doi: 10.1056/nejmct0910329.
- Heukelbach, J. and Feldmeier, H. (2002) ‘Scabies’, The Lancet, 367(9524), pp. 1767–1774. doi: 10.1016/s0140-6736(06)68772-2.
- Liang, S. Y. and Reno, H. E. (2015) ‘Infectious Disease/CDC Update. Update on Emerging Infections: News From the Centers for Disease Control and Prevention.’, Annals of emergency medicine, 66(5), pp. 527–8.
- ‘Rook’s Textbook of Dermatology’ (2016). doi: 10.1002/9781118441213.
- Salavastru, C. M. et al. (2017) ‘European guideline for the management of scabies’, Journal of the European Academy of Dermatology and Venereology, 31(8), pp. 1248–1253. doi: 10.1111/jdv.14351.
- Wilson, M.-M. G., Philpott, C. D. and Breer, W. A. (2001) ‘Atypical Presentation of Scabies Among Nursing Home Residents’, The Journals of Gerontology: Series A, 56(7), pp. M424–M427. doi: 10.1093/gerona/56.7.m424.
- Workowski, K. A., Bolan, G. A. and for and Prevention, C. (2015) ‘Sexually transmitted diseases treatment guidelines, 2015.’, MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports / Centers for Disease Control, 64(RR-03), pp. 1–137.