Scabies

This edited volume covers all aspects of the Neglected Tropical Disease Scabies. The contributions are organised into four themed parts. The first part reviews the history of the disease and its treatment and management, part two is dedicated to parasitology and basic research on the disease causing parasite, Sarcoptes scabei. Epidemiology and disease burden including public health issues are discussed in the third part in detail. The last section of the book is covering clinical manifestation and management. This volume is the first one of its kind, providing an insight into all aspects of the skin disease which is causing considerable morbidity and mortality. Chapters are all written by dedicated experts in their respective area of interest making the publication a must have for all scientists and clinicians as well as public health specialists dedicated to Scabies research in any aspect. Preface Contents Part I: History of Scabies 1: The European History of Scabies Research 1.1 The Sarcopt 1.2 The Dark Years 1.3 The Pioneers 1.4 The Lamentable Story of Jean-Chrysanthe Galès (1812–1829) 1.5 The Wonderful Story of Simon-François Renucci (1834) 1.6 Treatments References Part II: Parasitology and Basic Research 2: Biology of Sarcoptes scabiei and Its Relevance to Human Scabies: Clinical Symptoms, Treatment, and Management 2.1 Introduction 2.2 History of Scabies 2.3 Bio-Entomological Features of Sarcoptes scabiei 2.3.1 Classification 2.3.2 Morphology 2.3.3 Life Cycle 2.3.3.1 Egg 2.3.3.2 Larva 2.3.3.3 Nymph 2.3.3.4 Adult 2.3.3.5 Scybalum/Scybala 2.3.4 Physiology 2.3.5 Vectorial Role 2.4 Transmission of Scabies 2.5 Clinical Symptoms of Human Scabies in Relation to the Biology of Sarcoptes scabiei 2.5.1 Pathogenesis and Pathology 2.5.2 Clinical Presentations 2.5.2.1 Burrows 2.5.2.2 Papules 2.5.2.3 Nodules 2.5.2.4 Inflammation on the Burrows 2.5.2.5 Crusted Scabies 2.5.2.6 Other Clinical Characteristics 2.5.3 Diagnosis 2.6 Treatment 2.7 Management for Prevention of Further Spread 2.7.1 Prophylaxis 2.7.2 Control Management 2.8 Conclusions References 3: Genetic Studies of Sarcoptes scabiei: New Tools for Old Questions 3.1 Introduction 3.2 Results Based on Sequencing of Internal Transcribed Spacer 2 3.3 Results Based on Partial Sequencing of 16S and 12S Mitochondrial rRNA Genes 3.4 Results Based on Partial Sequencing of Cytochrome Oxidase Subunit I Gene 3.5 Results Based on Microsatellite Markers 3.6 Results Based on Other Markers 3.7 Conclusion References 4: Host Immune Response to Scabies 4.1 Introduction 4.2 Immunity and Hypersensitivity 4.3 Histopathology of Scabies Lesions 4.4 T-Cell Responses in Human Scabies 4.5 T-Cell Responses in Animal Scabies 4.6 Spectrum of T-Cell Responses in the Skin 4.7 Innate Cytokines and Chemokines 4.8 Antibody and Immunoglobulin Responses to Scabies 4.9 Scabies and House Dust Mite Cross-Reactivity 4.10 Recombinant Antigens 4.11 Vaccination 4.12 Conclusions References 5: Biochemical Research of Sarcoptes scabiei 5.1 The Need for Biochemical Research 5.2 Parasite Biology and Host–Parasite Interplay 5.2.1 Biochemical Discoveries on Scabies Mite Biology 5.2.2 Scabies Mite Host Immune Evasion 5.3 Biochemical Interactions Between the Mite and the Host 5.4 Applications of Biochemistry in Developing Advanced Diagnostics and Therapeutics for Scabies 5.4.1 Discoveries of Potential Diagnostic Markers 5.4.2 Promising Therapeutic and Vaccine Targets 5.4.3 Emerging S. scabiei Scabicide Resistance 5.5 Conclusion References 6: Scabies Multi-Omics to Identify Novel Diagnostic or Therapeutic Targets 6.1 Introduction 6.2 Potential of Multi-Omics Strategies 6.3 What Work Has Been Done on Mites, and Where Do We Stand in the Scabies Field? 6.3.1 Free-Living Mite Species 6.3.2 Obligate Parasitic Mite Species 6.4 Using Omics Technologies Assist to Discover New Intervention Targets? 6.4.1 Genome and Transcriptome Analysis 6.4.2 Gene Silencing and Non-Coding RNAs 6.5 Conclusion References 7: Scabies-Associated Microbiota 7.1 Why Should We Be Interested in Understanding the Microbiota Changes in the Context of Healthy Versus Diseased Skin? 7.1.1 The Skin Is a Dynamic Microenvironment 7.1.2 The Microenvironment of the Scabies Mite 7.2 What Do We Know About Microbes Associated with Scabies? 7.2.1 Epidemiology 7.2.2 Pig In Vivo and Ex Vivo Studies 7.2.3 In Vitro Studies Reveal Molecular Interactions Between Host, Mite and Bacteria 7.2.4 Histology 7.3 Research Questions, Methodologies and Challenges 7.3.1 Research Questions 7.3.2 What Methodologies Can Be Used to Study the Scabies-Associated Microbiota? 7.3.2.1 Animal Model Versus Human Studies 7.3.2.2 Methodologies of Molecular Data Generation Culture-Based Investigations 16S and ITS 1 Sequencing Whole-Genome Shotgun Metagenomics 7.3.3 Possible Pitfalls 7.3.3.1 Essential Patient Numbers 7.3.3.2 Confounding Factors 7.4 Conclusion References 8: Experimental Animal Models 8.1 Introduction 8.2 Existing Animal Models 8.3 Relevance of the Porcine Model 8.4 Development of a Pig Model to Advance Biomedical Scabies Research 8.5 Optimisation of the Pig Model to Allow Therapeutic Trial of New Acaricides 8.6 Conclusions 8.7 Supplemental Information References Part III: Epidemiology and Burden of Scabies: Public Health Issues 9: Scabies: Epidemiology and Risk Factors 9.1 Worldwide Distribution of Scabies 9.2 High Income Country Settings 9.3 Tropical and Resource-Poor Settings 9.4 Future Work on Disease Control References 10: Public Health Issues, Scabies Surveillance and Awareness 10.1 Institutional Scabies 10.1.1 Residential Care Homes 10.1.2 Schools 10.1.3 Prisons 10.1.4 Refugee Camps 10.2 The Burden and Impact of Scabies 10.2.1 Quality of Life and Disability 10.2.2 Economic Impact 10.3 Solutions References 11: Scabies and Secondary Infections 11.1 Introduction 11.2 Impetigo 11.2.1 Predisposition to Impetigo Due to Scabies 11.2.2 Clinical Presentation 11.2.3 Epidemiology of Scabies and Impetigo 11.2.3.1 Oceania 11.2.3.2 Asia 11.2.3.3 Africa 11.2.3.4 Middle East 11.2.3.5 Latin America 11.2.3.6 High-Income Countries 11.2.4 Treatment 11.2.5 Prevention 11.3 Complicated Skin and Soft Tissue Infections 11.4 Invasive Infections 11.4.1 Invasive Staphylococcus aureus Infections 11.4.2 Invasive Group A Streptococcus References 12: Morbidity of Scabies in Resource-Poor Communities 12.1 Introduction 12.2 Morbidity and Characteristics of Scabies in Resource-Poor Communities 12.3 Itching and Secondary Bacterial Infections 12.3.1 Sleep Disturbances and Socio-Emotional Aspects References 13: Morbidity of Scabies in Resource-Limited Countries: Rheumatic Heart Disease (RHD) and Post-Streptococcal Glomerulonephritis (APSGN) 13.1 Introduction 13.1.1 Introduction: The Links Between Scabies and Group A Streptococcus (GAS) 13.1.2 Secondary Infection of Scabies Lesions 13.1.3 Group A Streptococcal Pharyngitis Precedes Acute Rheumatic Fever: An Overview 13.1.4 Does GAS Skin Infection Result in ARF? 13.1.5 Conclusions 13.2 ARF & RHD 13.2.1 What Is ARF? Natural History, Diagnosis and Treatment 13.2.2 RHD and Long-Term Consequences 13.2.3 Morbidity and Mortality of Rheumatic Heart Disease (RHD) 13.2.4 Link Back to Scabies 13.3 Acute Articular Rheumatism 13.3.1 History and Examination 13.3.2 Pathogenesis 13.3.3 Investigations 13.3.4 Management 13.4 Acute Post-Streptococcal Glomerulonephritis (APSGN) 13.4.1 Introduction 13.4.2 Epidemiology: APSGN Link to Scabies Globally 13.4.3 Pathogenesis of APSGN and Contribution of Scabies 13.4.3.1 Acute GN Caused by Secondary Bacterial Infection 13.4.3.2 Immune Complex-Mediated Nephritis 13.5 Pathogenesis 13.5.1 Role of GAS 13.5.2 Bacterial Strain Specificity 13.5.3 Streptococcal Serotypes Associated with Epidemics 13.5.4 Investigations and Diagnosis 13.5.5 Diagnosis of Scabies 13.5.5.1 Diagnosis of APSGN 13.5.6 Management 13.5.6.1 Treatment of Scabies and Infection Scabies 13.5.6.2 Treatment of GAS Secondary Infection of Scabies 13.5.6.3 APSGN Management 13.5.6.4 Community Screening and Mass Drug Administration for Scabies 13.5.7 Strategies to Prevent Further Outbreaks of APSGN 13.5.7.1 Imperative to Prevent Childhood Illnesses That Result in Chronic Diseases That Are a Burden to Both the Patient and Healthcare System References 14: The International Alliance for the Control of Scabies (IACS) References Part IV: Clinical Manifestations and Management 15: Common Scabies and Special Presentations 15.1 Clinical Features of Common Scabies 15.1.1 Pruritus 15.1.2 Typical Lesions 15.1.3 Burrows 15.1.4 Historical Features 15.1.5 Applying the IACS Diagnostic Criteria 15.2 Atypical Presentations of Scabies 15.2.1 Scalp Involvement 15.2.2 Nodular Scabies 15.2.3 Bullous Scabies References 16: Scabies Itch 16.1 Scabies Itch: The Clinical Features 16.1.1 The Properties of Scabies Itch 16.1.2 The Prevalence of Scabies Itch 16.1.3 Consequences of Scabies Itch 16.2 The Suggested Pathophysiology of Scabies Itch 16.2.1 Host–Mite Interaction Which Possibly Contributes to Scabies Itch 16.2.2 Secondary Microbial Infection Which Likely Contributes to Scabies Itch 16.2.3 Sensitization: Possible Contribution to Scabies Itch 16.3 Scabies Itch Management 16.3.1 Treatment Directed on Scabies Mite 16.3.2 Scabies Itch Control 16.3.3 Proposed Measures for Refractory Itch References 17: Clinical Manifestations of Severe Scabies 17.1 Introduction to Terminology 17.2 Epidemiology 17.3 Risk Factors 17.4 Pathophysiology 17.5 Clinical Features 17.5.1 Severe Scabies 17.5.2 Crusted Scabies 17.5.3 Special Sites and Their Features That May Assist Clinical Diagnosis 17.5.3.1 Head 17.5.3.2 Hands, Feet and Nails 17.5.4 Clinical Presentation for Special Populations 17.5.4.1 Paediatric Patients 17.5.4.2 HIV/AIDS 17.5.4.3 Elderly and Immobile Patients 17.5.4.4 Pregnancy 17.5.4.5 Proposed Grading of Severity and Implications for Treatment: See Chap. 25 for More Detail 17.5.4.6 Complications 17.5.5 Secondary Infectious Complications 17.5.5.1 Bacterial 17.5.5.2 Viral 17.5.5.3 General Risks 17.5.5.4 Skin Specific 17.5.5.5 Stigma 17.6 Diagnosis 17.7 Confirmatory Diagnostic Methods 17.8 Emerging Confirmatory Diagnostic Methods 17.9 Supportive of Severe and Crusted Scabies References 18: Scabies in Infants and Children 18.1 Type of Lesions 18.1.1 Specific Lesions 18.1.1.1 Burrows 18.1.1.2 Nodules 18.1.1.3 Vesicles or Pustules 18.1.2 Non-Specific Lesions 18.2 Topography 18.3 Associated Symptoms 18.3.1 Pruritus 18.3.2 Familial Pruritus 18.4 Atypical Presentation of Scabies 18.4.1 Crusted Scabies, Norwegian Scabies 18.4.2 Bullous Scabies 18.5 Complications 18.5.1 Superinfection 18.5.2 Relapse and Recurrent Episodes 18.6 Differential Diagnosis: ‘Scabies Incognito’ 18.6.1 Atopic Dermatitis 18.6.2 Cutaneous Mastocytosis 18.6.3 Papular Urticaria and Prurigo Strophulus 18.6.4 Langerhans Cell Histiocytosis 18.6.5 Infantile Acropustulosis References 19: Parasitological Diagnosis of Scabies 19.1 Introduction 19.2 Clinical Lesions 19.2.1 Evocative Clinical Signs 19.2.2 Specific Lesions in Common Scabies 19.2.3 Specific Lesions in Crusted Scabies 19.3 Samples 19.3.1 Scratching Method 19.3.2 Adhesive Skin Cellophane Method 19.3.3 Identification with Light Microscopy 19.4 Indirect Methods 19.5 Conclusion References 20: Diagnosis of Scabies in Settings with Good Health Infrastructure 20.1 Introduction 20.2 “Scabies Incognito” and “Scabies Discreta” (“Well-Groomed Scabies”) 20.3 Diagnostic Measurements References 21: Diagnosis of Scabies in Resource-Poor Settings References 22: Potential for Sensitive and Simple Molecular Diagnostic Tools: Blood Tests for Scabies? 22.1 Introduction: Scabies and the Need for New Diagnostic Methods 22.2 PCR and Blood Tests Are Two Promising Pathways to Achieve This Objective 22.2.1 PCR 22.2.2 Historical Perspective 22.2.3 Outbreak Investigation 22.2.4 Method of PCR 22.2.5 PCR Targets 22.2.6 Sampling Method 22.2.7 Obstacles: Genetic Diversity, Interaction with House Dust Mites, and Cost 22.3 Blood Tests 22.3.1 Obstacles: Genetic Diversity, Interaction with Dust Mites, Kinetics and Clinical Relevance 22.3.2 Recombinant ELISA: A Promising Pathway 22.4 Conclusion References 23: Sarcoptic Mange in Wild and Domestic Animals 23.1 Introduction 23.2 Sarcoptic Mange in Wildlife 23.2.1 A Major Concern for Several Mammalian Species 23.2.2 Surveillance of Infection and Mite Exposure in Wild Animal Populations 23.2.3 Control Strategies of Sarcoptic Mange in Wildlife 23.3 Sarcoptic Mange in Domestic Animals 23.3.1 Sarcoptic Mange in Dogs 23.3.2 Sarcoptic Mange in Cats 23.3.3 Sarcoptic Mange in Pigs 23.3.4 Sarcoptic Mange in Domestic Herbivores 23.4 Cross Infections and Risk of Human Contamination from Animals References 24: Management of Common Scabies 24.1 Introduction 24.2 Permethrin 24.3 Topical Sulphur 24.4 Crotamiton 24.5 Benzyl Benzoate ± Tea Tree Oil 24.6 Oral Ivermectin 24.7 Lindane 24.8 Malathion 24.9 Treatment of Secondary Bacterial Infection 24.10 Treatment of Associated Dermatitis 24.11 Treatment of Pruritus 24.12 Household Management 24.13 Primordial Factors References 25: Management of Severe and Crusted Scabies 25.1 Introduction 25.2 Management of the Individual Patient with Crusted Scabies 25.3 Identification of People with Crusted Scabies 25.4 Challenges with Clinical Diagnosis (See Detail in Chap. 17) 25.5 Confirmatory and Supportive Diagnostic Testing (See Detail in Chap. 17) 25.6 Medical Treatment of the Index Case 25.6.1 Transfer Out to Hospital and Isolate 25.6.2 Workup 25.7 Assessment of Severity: Grading of Disease Morphology, Distribution and Complications 25.7.1 Systemic Treatment 25.7.2 Emerging Treatments 25.7.3 Topical Therapy 25.7.3.1 Topical Targeted Anti-Parasitic/Scabicidal Agents: An Additional Treatment to Oral Ivermectin 25.7.3.2 Topical Permethrin 5% Cream 25.7.3.3 Topical Benzyl Benzoate 25% Lotion 25.7.4 Other Topical Agents of Note 25.7.5 Guidelines: Variations in the Topical Regimen Protocols (in Addition to Systemic Therapy) 25.8 Removal of Surface Debris 25.8.1 Keratolytic Topical Agents 25.8.2 Physical Modalities 25.8.2.1 Management of Special Sites 25.9 Monitoring of the Index Patient for Complications: Additional Acute Care Requirements 25.10 Long-Term Care Considerations of the Affected Patient 25.11 Management of the Living Space/Community/Residential Facility 25.12 Management of Contacts 25.13 Treatment of Contacts and Management of Risks: Why It Matters 25.14 Identification: Outbreak Investigation and Contact Tracing 25.15 Other Considerations 25.15.1 Economics 25.16 Psychosocial Impact on the Individual and the Community 25.16.1 Cultural Factors Including Stigma and Normalisation 25.16.2 Organisational Stigma 25.16.3 Anxiety in Contacts 25.16.4 Psychological Complications 25.16.5 Social Barriers to Care 25.16.6 Further Opportunities References 26: Management of Pediatric Scabies 26.1 Overview 26.2 Drugs Available 26.3 Failures/Complications 26.4 Particularities of Newborn and Breastfeeding Women 26.5 Contact Cases, Communities, and Outbreaks 26.6 Environment References 27: Drug Resistance 27.1 Introduction 27.2 Clinical and Laboratory Evidence of Drug Resistance in Scabies Mites 27.2.1 Lindane 27.2.2 Permethrin 27.2.3 Ivermectin 27.3 Permethrin and Ivermectin Resistance in Other Parasites 27.4 Permethrin Resistance Mechanisms 27.4.1 Voltage-Gated Sodium Channel Alteration 27.4.2 Metabolic Detoxification and Other Mechanisms 27.5 Ivermectin Resistance Mechanisms 27.5.1 P-Glycoprotein and Other ABC Transporters 27.5.2 Ligand-Gated Chloride Channel Alteration 27.5.3 Metabolic Detoxification and Other Mechanisms 27.6 Conclusions and Future Research Directions References 28: Scabies Mass Treatment in Resource-Poor Countries 28.1 Introduction 28.2 Mass Drug Administration for Neglected Tropical Diseases 28.3 Mass Drug Administration and Scabies 28.4 Scabies and Mass Drug Administration Today 28.5 Integration with Other Mass Drug Administration Programmes 28.6 Strengths and Weaknesses of Mass Drug Administration for the Management of Scabies 28.7 Conclusion References 29: Scabies Management in Institutions 29.1 Epidemiology of Scabies in Institutional Settings 29.1.1 Prisons, Detention Centres, Refugee Camps and Homeless Settings 29.1.2 Adult Healthcare Settings 29.1.3 Child and Young People’s Establishments 29.2 Approach to the Assessment of Risk and Control of Scabies in Institutional Settings 29.2.1 An Approach to Assessing Scabies Transmission Drivers in Specific Institutional Settings to Guide Intervention and Treatment 29.2.2 The Importance of Epidemiological Assessment of Institutional Settings 29.2.3 Identification of Key Transmission Drivers in Institutional Settings 29.3 Outbreak Prevention and Control Interventions 29.3.1 Interventions Targeting Social and Environmental Drivers 29.3.2 Interventions Targeting Host Transmission Drivers 29.3.3 Interventions Targeting Transmission Drivers Related to Access to and Quality of Health and Care Services 29.3.4 Considerations in the Choice of Treatments 29.3.5 Communication During Outbreak Control 29.3.6 Summary and Checklist References 30: New Treatment Solutions 30.1 Limitations of Current Treatments for Scabies 30.2 The Optimisation of Treatment with Established Scabicide Drugs 30.3 The Repurposing of Drugs Used in the Veterinary Field 30.4 The Identification of New Drug Candidates Using Biochemical Research 30.5 Potential of Essential Oils in Treating Scabies 30.6 Conclusions References 31: Integrated Management of Scabies and Other Parasitic Diseases 31.1 Introduction 31.2 Scabies Coprevalence with Other Parasitic Diseases 31.3 Impact of Scabies 31.4 Integration of Scabies into Existing Public Health Platforms 31.4.1 Mapping and Surveillance 31.4.2 Mass Drug Administration of Ivermectin and Integrated Management 31.4.3 Barriers, Facilitators, and Future Directions References