Crusted scabies; a 2-year prospective study from the Northern Territory of Australia

A systematic review of immunosuppressive risk factors and comorbidities associated with the development of crusted scabies

OBJECTIVES

Crusted scabies (CS, Norwegian scabies) is a severe form of scabies, characterized by hyper-infestation of Sarcoptes scabiei mites. CS is commonly associated with immunosuppression but is also reported in overtly immunocompetent individuals. We reviewed immunosuppressive risk factors and comorbidities associated with CS.

METHODS

The National Library of Medicine (PubMed) database was reviewed for patient case reports of CS from January 1998 to July 2023. Two authors screened records for eligibility, extracted data, and one critically appraised the quality of the studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023466126.

RESULTS

A total of 436 records were identified, of which 204 were included for systematic review. From these, 683 CS patients were included. CS impacted both genders equally. Adults (21-59 years) were more commonly affected (45.5%) compared to children (0-20 years, 21%). Corticosteroid use was the most prevalent immunosuppressive risk factor identified (27.7% of all cases). About 10.2% of reports were associated with HIV/AIDS, and 8.5% with HTLV-1 infection. 10.5% of patients were overtly immunocompetent with no known risk factors. Overall, 41 (6.0%) died, many subsequent to secondary bacteremia.

CONCLUSION

This study represents the first systematic review undertaken on immunosuppressive risk factors associated with CS. This provides insights into trends of immunosuppression and mechanisms of CS development.

Case report of crusted scabies, brief review of its pathophysiology and latest data

Background

Crusted scabies is a rare form of parasitic infection provoked by a massive infestation of the ectoparasite Sarcoptes scabiei varietas hominis on human skin. It is an extremely contagious type of disease and can even lead to a social stigma. In European countries like Greece, many cases remain undiagnosed for long periods, causing extreme distress in the patient's everyday life and social environment.

Case Description

Herein, we present a case of an 86-year-old woman with crusted scabies in Greece, who remained undiagnosed for 5 months. Massive hyperkeratotic plaques on the extremities, and face, palmoplantar keratoderma, and numerous small erythematous papules on the torso with extreme itch were the main clinical manifestations of the patient. Dermoscopy revealed the parasite. All necessary decontamination measures were taken by personnel. Treatment was administered and a complete cure of the disease was observed.

Conclusions

In this case, the use of dermoscopy has attributed to precise crusted scabies diagnosis and acute pharmacological management of the patient. Early diagnosis of such diseases not only saves patients from lethal secondary infections, but also reduces the risk of a massive scabies outbreak. We also conducted a mini-review, analyzing all recent data concerning crusted scabies macroscopic, dermatoscopic, and histological images. All new information concerning the pathophysiological mechanism of crusted scabies manifestation, updated treatment options, and potential resistance to widely-used treatments are provided.

Severe Scabies: A French Multi-centre Study Involving 95 Patients with Crusted and Profuse Disease and Review of the Literature

The aim of this multi-centre French retrospective study was to identify severe, i.e. crusted and profuse, scabies patients. Records were retrieved from 22 Dermatology or Infectious Diseases departments in the Ile-de-France from January 2009 to January 2015 to characterize epidemiology, demography, diagnosis, contributing factors, treatment features, and outcomes in severe scabies. A total of 95 inpatients (57 crusted and 38 profuse) were included. A higher number of cases was observed among elderly patients (>75 years), mostly living in institutions. Thirteen patients (13.6%) reported a history of previously treated scabies. Sixty-three patients (66.3%) had been seen by a previous practitioner for the current episode (up to 8 previous visits). Initial misdiagnosis (e.g. eczema, prurigo, drug-related eruptions, psoriasis) was documented in 41 patients (43.1%). Fifty-eight patients (61%) had already received 1 or more previous treatments for their current episode. Forty percent received corticosteroids or acitretin for an initial diagnosis of eczema or psoriasis. Median time from the onset of symptoms to the diagnosis of severe scabies was 3 months (range 0.3-22). Itch was present in all patients at diagnosis. Most patients (n=84, 88.4%) had comorbidities. Diagnostic and therapeutic approaches varied. Complications occurred in 11.5% of cases. To date, there is no consensus for diagnosis and treatment, and future standardization of is required for optimal management.

Combination of Crusted Scabies with Bullous Scabies: A Rare Case

Scabies is a parasitic skin disease caused by Sarcoptes scabiei var. hominis. Crusted scabies, also known as Norwegian scabies, is a rare and severe form of scabies that occurs more frequently in immunocompromised, elderly, disabled, and debilitated patients. The present study reports a case of crusted scabies combined with bullous scabies. A 44-year-old man was admitted with the chief complaint of red, thick, scaly patches of skin accompanied by crusting that felt itchy and worsened at night. The lesions had appeared all over his body intermittently for the last 10 years; however, the complaints worsened in the last 2 months. From dermatological status, the anterior and posterior thoracic regions and between the fingers of both hands showed generalized distribution of erythematous, yellowish, hyperkeratotic plaques with clear boundaries, pustules, and blisters on an erythematous base with multiple erosions and excoriations. S. scabiei were found on skin scraping examination, and histopathological examination supported the diagnosis of bullous scabies. The patient received 5% permethrin lotion topical therapy and systemic ivermectin therapy. In addition, the patient was given systemic antibiotics. The lesions improved after 2 weeks of therapy, and no S. scabiei were found on the subsequent microscopic examination. Treatment with a combination of topical and systemic scabicidal agents produced a favorable outcome in this patient.

Crusted Scabies, a Neglected Tropical Disease: Case Series and Literature Review

Crusted scabies is a rare form of scabies that presents with more severe symptoms than those of classic scabies. It is characterized by large crusted lesions, extensive scales, thick hyperkeratosis, and contains a large number of highly contagious itch mites. Crusted scabies is more prevalent in immunocompromised, malnourished, and disabled individuals. This disease has been linked to a variety of health problems, including delayed diagnosis, infection risk, and high mortality, mainly from sepsis, and it has the potential to cause an outbreak due to its hyper-infestation, which makes it highly infectious. This article reports three cases of crusted scabies in North Sulawesi, Indonesia. Recent updates and a comprehensive review of the literature on the disease are also included, emphasizing the critical importance of early diagnosis and effective medical management of patients, which are necessary to prevent the complications and spread in communities.

Health care cost of crusted scabies in Aboriginal communities in the Northern Territory, Australia

Background

Crusted scabies is a debilitating dermatological condition. Although still relatively rare in the urban areas of Australia, rates of crusted scabies in remote Aboriginal communities in the Northern Territory (NT) are reported to be among the highest in the world.

Objective

To estimate the health system costs associated with diagnosing, treating and managing crusted scabies.

Methods

A disease pathway model was developed to identify the major phases of managing crusted scabies. In recognition of the higher resource use required to treat more severe cases, the pathway differentiates between crusted scabies severity grades. The disease pathway model was populated with data from a clinical audit of 42 crusted scabies patients diagnosed in the Top-End of Australia’s Northern Territory between July 1, 2016 and May 1, 2018. These data were combined with standard Australian unit costs to calculate the expected costs per patient over a 12-month period, as well as the overall population cost for treating crusted scabies.

Findings

The expected health care cost per patient diagnosed with crusted scabies is $35,418 Australian dollars (AUD) (95% CI: $27,000 to $43,800), resulting in an overall cost of $1,558,392AUD (95% CI: $1,188,000 to $1,927,200) for managing all patients diagnosed in the Northern Territory in a given year (2018). By far, the biggest component of the health care costs falls on the hospital system.

Discussion

This is the first cost-of-illness analysis for treating crusted scabies. Such analysis will be of value to policy makers and researchers by informing future evaluations of crusted scabies prevention programs and resource allocation decisions. Further research is needed on the wider costs of crusted scabies including non-financial impacts such as the loss in quality of life as well as the burden of care and loss of well-being for patients, families and communities.

Crusted scabies is characterised by thick skin crusting and fissuring and can lead to serious secondary infections and death from complications. Rates of crusted scabies in remote Aboriginal communities in the Northern Territory (NT) are among the highest in the world. Efforts are on the way in Australia to prevent, if not eliminate, crusted scabies. We use data from a clinical audit of 42 patients diagnosed with crusted scabies in the Top-End of the NT to estimate the health system costs associated with diagnosing, treating and managing crusted scabies for patients and their households. This cost of illness study can provide a valuable starting point for policy makers and evaluators in estimating the potential economic impact of crusted scabies prevention programs on health care service use and costs.

Tratamiento de la escabiosis

La escabiosis afecta a más de 200 millones de personas en el mundo, y ocasiona un importante impacto socioeconómico. El mecanismo de contagio es por contacto directo prolongado. El contagio por fómites es infrecuente, aunque puede ser importante en la sarna noruega. La terapia con permetrina tópica al 5% es recomendada como tratamiento de primera línea. Puede indicarse durante el embarazo y la lactancia, y parece ser segura en niños < 2 meses. Sin embargo, últimamente se ha reportado una disminución de la efectividad de este fármaco. Otra alternativa en primera línea terapéutica es la ivermectina oral. Se puede administrar durante la lactancia, y estudios recientes sugieren que es segura en niños y lactantes pequeños. Diversas revisiones sistemáticas y metaanálisis han concluido que la ivermectina oral es tan efectiva y segura como la permetrina tópica. La administración terapéutica «en masa» de ivermectina oral es una excelente opción para el manejo de escabiosis en comunidades con alta prevalencia o de brotes en instituciones.

Crusted Scabies Infection in the Setting of Chronic Steroid and Omalizumab Use

Scabies infection is a very common skin disease that occurs due to infestation with the Sarcoptes scabei mite. Typically, it results in intensely pruritic papules and excoriations in the webs of the hand, groin, or axilla, and remains limited in its spread. In rare cases, the disease can become diffuse and progress to crusted or nodular subtypes. Here, we report the case of crusted scabies infestation in a 69-year-old male who presented with a diffuse pruritic, erythematous, and petechial rash. His medical history was significant for severe idiopathic urticaria treated with omalizumab. Before starting omalizumab, the patient was self-medicating for several months with corticosteroids obtained through his veterinary practice to alleviate symptoms. His presentation was complicated by immune thrombocytopenic purpura and muscle weakness, likely secondary to omalizumab and corticosteroid use, respectively. The patient underwent an extensive rheumatologic workup until skin biopsy confirmed the underlying etiology as crusted scabies infestation. He was treated with ivermectin and weekly 5% permethrin skin cream with great improvement of his rash; however, unfortunately, he succumbed to bacterial sepsis. Scabies infestation can masquerade as a manifestation of other systemic diseases and is often misdiagnosed. As this case illustrates, initial misdiagnosis and subsequent treatment with immunosuppressive drug regimens can cause preventable, but potentially fatal, concomitant superinfections.

Active case detection methods for crusted scabies and leprosy: A systematic review

BACKGROUND

Crusted scabies is endemic in some remote Aboriginal communities in the Northern Territory (NT) of Australia and carries a high mortality risk. Improvement in active case detection (ACD) for crusted scabies is hampered by a lack of evidence about best practice. We therefore conducted a systematic review of ACD methods for leprosy, a condition with similar ACD requirements, to consider how findings could be informative to crusted scabies detection.

METHODS AND PRINCIPLE FINDINGS

We conducted systematic searches in MEDLINE, CINAHL, Scopus and the Cochrane Database for Systematic Reviews for studies published since 1999 that reported at least one comparison rate (detection or prevalence rate) against which the yield of the ACD method could be assessed. The search yielded 15 eligible studies from 511. Study heterogeneity precluded meta-analysis. Contact tracing and community screening of marginalised ethnic groups yielded the highest new case detection rates. Rapid community screening campaigns, and those using less experienced screening personnel, were associated with lower suspect confirmation rates. There is insufficient data to assess whether ACD campaigns improve treatment outcomes or disease control.

CONCLUSION

This review demonstrates the importance of ACD campaigns in communities facing the highest barriers to healthcare access and within neighbourhoods of index cases. The potential benefit of ACD for crusted scabies is not quantified, however, lessons from leprosy suggest value in follow-up with previously identified cases and their close contacts to support for scabies control and to reduce the likelihood of reinfection in the crusted scabies case. Skilled screening personnel and appropriate community engagement strategies are needed to maximise screening uptake. More research is needed to assess ACD cost effectiveness, impact on disease control, and to explore ACD methods capable of capturing the homeless and highly mobile who may be missed in household centric models.

First Description of the Composition and the Functional Capabilities of the Skin Microbial Community Accompanying Severe Scabies Infestation in Humans

Epidemiological studies link Sarcoptes scabiei infection and impetigo. Scabies mites can promote Streptococcus pyogenes (Group A Streptococcus) and Staphylococcus aureus infections by breaching the skin barrier and excreting molecules that inhibit host innate immune responses. However, little is known about the composition and the function of the scabies-associated microbiota. Here, high-throughput whole-metagenome sequencing was used to explore the scabies-associated microbiome. Scabies mites including their immediate microenvironments were isolated from two patients with severe scabies in Northern Australia. Two ~45–50 million paired-end reads Illumina libraries were generated of which ~2 (5.1%) and 0.7 million (1.3%) microbial reads were filtered out by mapping to human (hg19) and mite draft genomes. Taxonomic profiling revealed a microbial community dominated by the phylum Firmicutes (A: 79% and B: 59%) and genera that comprise Streptococcus, Staphylococcus, Acinetobacter, and Corynebacterium. Assembly of the metagenome reads resulted in genome bins representing reference genomes of Acinetobacter baumannii, Streptococcus dysgalactiae (Group C/G), Proteus mirablis and Staphylococcus aureus. The contigs contained genes relevant to pathogenicity and antibiotics resistance. Confocal microscopy of a patient skin sample confirmed A. baumannii, Streptococci and S. aureus in scabies mite gut and faeces and the surrounding skin. The study provides fundamental evidence for the association of opportunistic pathogens with scabies infection.