Suspected Scabies on a Long-Term Care Unit
A 240-bed skilled nursing facility has three residents on the same wing with new, intensely itchy papular rashes over the past ten days. One resident has crusted, scaly lesions on the hands and elbows. Two staff members on that wing report itching that worsens at night. The unit has 28 residents, many with dementia who ambulate freely and share a dining room. The director of nursing asks the infection preventionist whether to 'just treat the three residents and watch.' It is Friday afternoon; the dermatologist is unavailable until Monday, and skin scrapings are not performed on site. The facility has no negative-pressure rooms and limited single rooms.
1. How should the IP weigh the evidence and decide whether this is an outbreak requiring broader action?
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The IP should treat the constellation as a probable outbreak and act on it, not wait for Monday:
- Case definition and count. Three residents with compatible pruritic rash plus two symptomatic staff on one wing exceeds what would be expected by chance on a single unit. The crusted, scaly lesions raise the specific concern of crusted (Norwegian) scabies, which is far more transmissible than ordinary scabies because of the mite burden in scale.
- The 'treat three and watch' plan is inadequate because scabies has a long incubation (up to 4–6 weeks in people without prior exposure), so additional cases are almost certainly already incubating. Treating only visible cases guarantees a second wave.
- Diagnosis does not need to wait. Scraping is helpful but not required to act when clinical and epidemiologic findings are strong. A therapeutic trial with a scabicide plus expert consultation by phone is reasonable.
- Staff cases are epidemiologically significant - they suggest transmission within the facility and mean the exposure net includes coworkers and their households.
- Practical constraints (no negative pressure, limited single rooms) shape implementation but do not justify delay; scabies is transmitted by skin-to-skin contact and fomites, not by airborne route, so negative pressure is irrelevant. The relevant controls are contact precautions, cohorting, and environmental cleaning.
2. Design the immediate control plan, including who gets treated and how the facility manages its room constraints.
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A defensible plan has four parts:
- Treat broadly, not narrowly. Provide scabicide treatment to all residents and all staff on the affected wing (and any staff who had prolonged skin contact with the crusted case), plus household contacts of affected staff. Simultaneous treatment on the same day is essential - sequential treatment allows reinfection. For the crusted case, combine a topical scabicide with an oral agent per prescriber direction and repeat treatment as directed.
- Contact precautions. Place the crusted case in a single room if possible and use gloves and gown for all contact until treatment is complete and scaling resolved; for ordinary cases, standard precautions plus gloves for direct care are generally sufficient after treatment begins. Cohort exposed residents together if single rooms are scarce - cohorting is the accepted workaround when private rooms are unavailable.
- Environment and fomites. Launder bedding, clothing, and towels in hot water and dry on high heat; bag and set aside items that cannot be laundered for several days. Clean shared surfaces and equipment. Do not attempt fumigation - it is ineffective and hazardous.
- Communication and monitoring. Notify the medical director, prescriber, and staff; provide plain-language education about the itch persisting for weeks after successful treatment (so people do not assume failure and re-treat unnecessarily). Establish active surveillance for new rashes over the next 4–6 weeks, and screen new admissions and transfers during the surveillance period.
3. What should the IP tell the director of nursing about the crusted case specifically, and about when the outbreak can be declared over?
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On the crusted case:
- Crusted scabies is the engine of an outbreak. The scale contains enormous numbers of mites, and shedding of scale can contaminate the immediate environment. This resident warrants the most aggressive treatment and the longest duration of contact precautions - until treatment is completed and crusting has resolved, not merely until symptoms improve.
- Staff providing care should be specifically trained and should use gown and gloves for any contact, and the room should be cleaned thoroughly and frequently.
- The resident's close contacts, including roommates and frequent visitors, should be treated prophylactically.
On declaring the outbreak over:
- Do not use 'no new cases this week' as the endpoint. Because incubation can run 4–6 weeks, surveillance must continue through at least one full incubation period (commonly cited as 6 weeks) after the last case is treated.
- The outbreak can be considered controlled when no new epidemiologically linked cases appear through that surveillance window, all identified cases and contacts have completed treatment, and environmental measures are documented.
- The IP should also state the criteria in writing to the DON so the endpoint is not negotiated ad hoc, and should schedule a review of the wing's laundry and shared-equipment practices, since those are common amplification points in long-term care.