Author: Dr David Lim, Dermatology Registrar, Waikato Hospital, Hamilton, New Zealand, 2010.
Institutional scabies is defined as scabies affecting occupants of a residential facility. Residential facilities include:
Only one resident needs to be infested with scabies for it to be considered institutional scabies.
Institutions should be on the alert for scabies all year round. A rash affecting more than one resident or staff member should be considered scabies until proven otherwise.
Scabies can take many different forms and is commonly missed by inexperienced health practitioners. Input from a specialist Dermatologist should be obtained if there is doubt over the diagnosis.
The main clinical presentations of scabies are:
All presentations of scabies may occur in institutions, but crusted scabies is more prevalent in rest homes and hospitals than in normal households as it mostly affects the elderly, sick or immunosuppressed.
Treatment of institutional scabies requires careful consideration and planning. Treatment failures are common when it is not co-ordinated or carried out appropriately. This substantially increases costs and the time involved in treatment.
Early diagnosis and treatment is the key. However, treatment should not be rushed into without planning, even for single cases. Two-way communication between a resident's doctor and the facility manager is paramount. This is to ensure that both are aware of new and previous infestations of scabies. The facility manager should be notified of all cases of scabies before treatment is commenced. This allows coordinated diagnosis and treatment of other residents to occur. Treating an individual for scabies when they are surrounded by an ongoing scabies outbreak is futile and wastes time and financial resources.
Research has shown that mites can survive off human hosts for 2-5 days at normal room temperatures and humidty. Eggs can survive up to 7 days under ideal conditions (90% humidity and 10° C / 50° F). It is therefore important to clean bedding and clothes the morning after each scabicide treatment. This should be done with hot water followed by drying in an electric dryer at the highest temperature setting. Non washable items should be sealed in a plastic bag and stored above 20° C for one week. Alternatively they can be frozen below -20° C for 12 hours. Rooms should be thoroughly cleaned with normal household products. Fumigation or specialised cleaning is not required. Carpeted floors and upholstered furniture should be vacuumed and all areas cleaned with normal household products. The vacuum bag should then be discarded and furniture covered by plastic or a sheet during treatment and for 7 days after.
Staff should be restricted to working within one area or wing of a facility during an outbreak. This will help limit the number of affected cases.
Different scenarios require different treatment plans. These are described below.
All new residents to a facility should be isolated until a full skin examination can be performed. The skin check should occur within 24 hours of arrival. Appropriate contact precautions for scabies should be used until the skin check can be performed. Any skin rashes found need to be diagnosed with minimal delay. A low threshold for treatment for scabies should be maintained. Treatment is low risk and the downside of treating an individual when the diagnosis is equivocal is minimal when compared to treating the whole facility for an outbreak.
We do not recommend the enforced and routine treatment of all new residents to a facility who do not have scabies. This approach would be legally and ethically questionable.
The contact precautions required for scabies include gloves, gowns and the avoidance of direct skin to skin contact. This should be maintained until at least 8 hours after treatment.
At all other times, staff should use alcohol-containing sanitisers / hand rubs frequently.
If a single resident is diagnosed with scabies, the facility manager should be notified before treatment is commenced. Other residents and staff within the same wing should have a full skin check. This should take place even if the resident is asymptomatic, particularly in rest homes. Residents of rest homes are often elderly and debilitated when they may not complain of itch nor scratch. When only one resident is diagnosed with scabies they should be treated with topical treatments alone.
Specific medications and methods treatment are described below.
This requires the co-ordinated treatment of residents, staff and frequent visitors. The outbreak will be near impossible to control if this is not done. The facility manager should be notified before treatment is commenced. If all individuals are unable to be treated concurrently, then treatment should be deferred until this is possible.
If all the residents diagnosed with scabies reside within the same wing then only residents, staff and frequent visitors of the affected wing require treatment. However, if there is more than one wing affected then the whole facility requires treatment.
Individuals can be treated with either topical or oral medication or a combination. Topical applications are time consuming, taking up to one hour per resident. Oral treatment is easier and much less time consuming to carry out. Unfortunately it can be expensive or even unavailable. Institutions should enquire about cost, funding options and availability in their area.
When more than one resident is affected it is likely that a resident within the facility has crusted scabies. Crusted scabies is highly contagious and effort should be put into finding this individual who may be asymptomatic and perhaps diagnosed with another skin disorder such as psoriasis. Crusted scabies requires extra treatment and care.
Specific medications and methods for treatment are described below.
Itch and the scabies rash may take up to one month to settle completely following successful treatment. Examination by an expert (e.g. specialist dermatologist) may be appropriate to confirm the diagnosis when there is a persistent rash lasting more than one month after treatment.
When scabies persists or recurs within a facility within a few months all residents and staff should be treated regardless of whether it was previously considered to be confined to a particular room or wing.
Topical insecticide treatments such as malathion and permethrin are relatively cheap and readily available. However, they are time consuming to apply properly, taking about 1 hour per application. They are the preferred treatment when only a few residents require treatment, and for staff, visitors and their family members.
Permethrin is often considered a second-line option for community scabies and reserved for failure after treatment with malathion or other agent. However, due to the difficulties of treating institutional scabies it should be considered a first line option in this setting, as it is currently the most effective topical scabicide.
The 5% permethrin lotion or cream should be applied to every patch of skin from the neck to the toes. It should be left on for 8-14 hours and then washed off. Individuals should have a repeat application after 1 week. It is important that a staff member supervises treatment to ensure thorough application of the insecticide.
The reported cure rate in research studies has been up to 98% with two applications of permethrin, but lower rates are usual in normal practice. Those with an impaired functional status have lower cure rates with topical permethrin, probably because they carry more mites. Oral treatment should be considered for these individuals.
Ivermectin is the sole oral treatment available. Ivermectin is preferred when many residents require treatment. The co-ordinated topical treatment of many residents is difficult and time consuming.
The recommended dose for ivermectin is 200mcg/kg (15mg for a 75 kg person). This should be repeated in 7-14 days. Side effects from ivermectin are uncommon and are usually minor. Serious neurological side effects can rarely occur particularly in debilitated people.
Crusted scabies may require three to four doses at 7-14 day intervals. Occasionally, weekly treatment may be necessary for longer.
The few studies reporting on the efficacy of ivermectin have variable cure rates. However, studies indicate that two ivermectin doses of 200mcg/kg 1-2 weeks apart effects a cure in more than 90% of cases. Single dose treatment is less reliable with cure rates around 70% in immunocompromised patients. The low cure rates with single dosing may be due to the survival of eggs and re-infestation.
A pragmatic approach may be to treat all residents with oral ivermectin, and those with burrows should have additional topical insecticide applied to hands and under the nails. This should improve cure rates and reduce transmission of mites.
Crusted scabies needs thorough treatment and careful follow-up to ensure cure.
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