Elsevier

Journal of Infection

Volume 50, Issue 5, June 2005, Pages 375-381
Journal of Infection

Review
Crusted scabies: clinical and immunological findings in seventy-eight patients and a review of the literature

https://doi.org/10.1016/j.jinf.2004.08.033Get rights and content

Abstract

Objectives

To describe the clinical and immunological features of crusted scabies in a prospectively ascertained cohort of 78 patients.

Methods

All patients requiring inpatient treatment for crusted scabies in the ‘top end’ of the northern territory of Australia over a 10 year period were prospectively identified. Demographics, risk factors, and immunological parameters were retrospectively compiled from their medical records and pathology databases.

Results

More than half the patients with crusted scabies had identifiable immunosuppressive risk factors. Eosinophilia and elevated IgE levels occurred in 58% and 96% of patients, respectively, with median IgE levels 17 times the upper limit of normal. Seventeen percent had a history of leprosy but 42% had no identifiable risk factors. There was a decrease in mortality after the introduction of a treatment protocol consisting of multiple doses of ivermectin combined with topical scabicides and keratolytic therapy.

Conclusions

Crusted scabies often occurs in patients with identifiable immunosuppressive risk factors. In patients without such risk factors, it is possible that the crusted response to infection results from a tendency to preferentially mount a Th2 response. The treatment regime described was associated with a reduction in mortality. This is the largest reported case series of crusted scabies.

Section snippets

Summary

Crusted or Norwegian scabies is rare and is usually associated with underlying immunodeficiency. It results from hyper-infestation following infection with Sarcoptes scabiei and historically had a 5 year mortality rate of up to 50%. The clinical and immunological features of a series of 78 prospectively identified patients over a 10 year period are described from northern Australia and compared with the literature. Immunosuppressive risk factors were identified in over half. Eosinophilia and

Cases

The tropical ‘top end’ of the northern territory of Australia has a population of approx. 140 000 in an area of 516 945 km2. Around 24% of the population are indigenous (Aboriginal) Australians, many of whom live in small remote communities. Royal Darwin Hospital is the 300 bed referral hospital for the region. All patients in the top end of the northern territory requiring in-hospital treatment for crusted scabies over the 10 year period January 1991 through December 2000 were included. The

Results

Seventy-eight patients with crusted scabies from the top end of the northern territory were identified and treated over the 10 years (Table 1). There were only two children, aged 1 month and 15 years. Disease was otherwise spread evenly across the adult years, with the mean age being 43 years and the oldest patient 76 years of age (Fig. 3). All but 2 patients were indigenous Australians from remote Aboriginal communities. High mite counts were demonstrated by light microscopy in 71% of patients.

Discussion

This is the largest reported case series of crusted scabies. Although these 78 cases over 10 years represent an overall prevalence of less than 0.1%, crusted scabies in northern Australia is almost unique to the Aboriginal population in which the prevalence is higher. Crusted scabies is associated with substantial morbidity and stigma related to the debilitating skin condition. It has also been associated with high mortality, either from secondary sepsis or from the underlying predisposing

Acknowledgements

We are indebted to our medical and nursing colleagues at Royal Darwin Hospital, including Gabriel O'Kane, Alison Bucklar, Daniel O'Brien, Adam Jenney, Julian Elliott, Mark Douglas, Marilyn Hassell, Josh Davis, Anna Ralph, Emma Spencer, Dale Fisher, Nick Anstey and Ric Price for meticulous patient care and assistance with these studies.

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