Schistosomiasis

The following sections are included:

• About the Series Editors

• List of Contributors

• Preface

• Contents

Human infections with the parasitic helminths of the family Schistosomatidae represent a significant segment of the global burden of illness. Members of this family are estimated to infect 200–300 million people and to be endemic in more than 70 countries. The schistosomes share the major biological and epidemiological features of macroparasites (1–4). The central theme of this concept is the recognition that macroparasites, in general, do not multiply within the definitive host. In the case of schistosomes, increase in the population of the pathogen occurs only in the snail intermediate host while adult worms in humans or experimental animals are unable to expand their numbers without acquisition of new infections from the environment. The second fundamental concept concerns the host–parasite relationship in schistosomiasis, as well as other helminthic infections: it relates to the dependence of the outcome of infection and disease on numbers of parasites in the host. This correlation however is not exact, as there has been recognition in recent years of the multiplicity of other factors such as the genetics of the parasite and/or host, the role of other infections and perhaps host nutrition in shaping or modifying the outcome of host–parasite interaction. Our current appreciation indicates that infection and disease in schistosomiasis is a multifactorial process, although the intensity of infection seems to be the dominant factor…

The following sections are included:

• Introduction and Historical Background

• Basic Life Cycle

• Schistosomes Affecting Humans and Their Distribution
  • Species of Widespread Importance
  • Species of Local Importance
  • Other Schistosome Infections

• Anatomy and Biology of the Schistosome Life Cycle Stages
  • Eggs
  • Miracidia
  • Primary and Secondary Sporocysts
  • Cercariae
  • Schistosomula
  • Adult Worms

• The Intermediate Hosts
  • General Taxonomy
  • Taxonomy, Life Cycles and Biology of the Intermediate Hosts
  • Ecology and Control of Intermediate Hosts
  • Snail-Schistosome Interactions in the Field

• References

The following sections are included:

• Introduction

• Schistosome Genome Organization
  • The Mitochondrial Genome
  • Repetitive DNA Sequences
  • The Structure and Organization of Genes
  • Differential Expression of Genes
  • Regulation of Gene Expression

• The Genetic Diversity of Schistosomes

• The Schistosome Genome Project

• Acknowledgments

• References

The following sections are included:

• Introduction

• How Efficient Is Schistosome Transmission?
  • Determination of Prevalence and Intensity of Schistosome Infection
  • Transmission of Schistosomiasis in Travelers and Other Nonimmune Populations
  • Infection and Reinfection in Endemic Populations

• Estimation of Local Transmission Potential
  • Snail Monitoring
  • Cercariometry
  • Environmental Factors Affecting Transmission

• The Epidemiological Profile of Chronic Schistosomiasis
  • Age-Prevalence and Age-Intensity Curves
  • Contrast with Other Flukes

• Duration of Infection
  • Adult Worm Survival in Human Populations
  • Adult Fecundity

• Influence of Host Factors on Transmission
  • Water Contact Behavior
  • Water Contamination
  • Inherent and Acquired Host Resistance to Infection

• Human Influence on the Ecology of Transmission
  • The Influence of Migration and Urbanization
  • The Impact of Water Source Modification

• Conclusions

• Acknowledgments

• References

The following sections are included:

• Introduction

• Patterns of Human Infection in Schistosomiasis Endemic Areas

• Evidence for Immunity to Infection in Untreated Human Populations

• Treatment–Reinfection Population Studies in Schistosomiasis Endemic Areas

• The Influence of Exposure in Patterns of Infection

• Acquired Versus Innate Resistance to Reinfection

• Acquired Immunity; Age per se or Cumulated Experience of Infection

• Immunological Correlates of Resistance to Reinfection

• Schistosome Antigens Associated with Human Resistance to Reinfection

• Factors That Influence the Expression of Potentially Protective Immune Responses

• Genetic Analysis of Human Resistance to Reinfection

• What Is the Relationship Between Schistosomiasis Age–Infection Profiles and Acquired Immunity?

• Why Use Experimental Animals?

• Innate Resistance to Schistosomes in Animal Models

• Resistance to Reinfection Induced by Normal Infections
  • Schistosoma mansoni in Rodent Models
  • Schistosoma haematobium in Rodent Models
  • Schistosoma bovis in Rodents and Other Animals
  • Schistosoma japonicum in Rodent Models
  • Schistosoma mansoni and S. haematobium in Primate Models

• Resistance Induced by the Radiation-Attenuated (RA) Vaccine
  • RA Vaccine-Induced Resistance to Schistosoma mansoni in Rodent Models
  • RA-Vaccine-Induced Resistance to S. haematobium and S. bovis in Rodent and Other Animal Species
  • RA-Vaccine-Induced Resistance to S. japonicum in Rodent and Other Animal Species
  • RA-Vaccine-Induced Resistance to Schistosoma mansoni and S. haematobium in Primate Models

• Resistance Induced by Native and Recombinant Schistosome Antigens
  • Glutathione S-Transferases
  • Triose Phosphate Isomerase (TPI)
  • Sm14
  • Sm23
  • Myosin Heavy Chain (IrV-5)
  • Paramyosin
  • Glyceraldehyde-3-Phosphate Dehydrogenase (G3PDH)
  • Calpain
  • Other Candidate Vaccine Antigens

• Conclusions

• Acknowledgments

• References

The following sections are included:

• Overview

• Infection vs. Disease in Human Schistosomiasis

• Perinatal Exposure to Schistosomiasis and Its Impact on the Immune Response

• Genetic Effects on Susceptibility to Disease

• Disease Mediated by Nonimmune Mechanisms

• Immunopathology and Its Immunoregulation
  • Acute Infection
  • Chronic Infection
  • Granulomas
  • Fibrosis

• Immunomodulation
  • Human Schistosomiasis
  • Experimental Models of Schistosomiasis

• Conclusions and Unresolved Questions

• Acknowledgment

• References

The following sections are included:

• Introduction

• The Pathogen

• Immunopathology of Schistosomiasis Haematobia

• Epidemiology of S. haematobium Infection

• Morbidity Due to S. haematobium Infection
  • Stages of Disease
  • Bladder Disease
  • Ureters
  • Reproductive Tract
  • Intestinal Tract and Liver Disease
  • Lung and Chest Disease
  • Skin Disorders
  • Central Nervous System Disease

• Renal Parenchymal Disease Associated with S. haematobium Infection

• Carcinoma of the Bladder

• Other Manifestations of Infection

• Diagnosis

• Imaging of Structural Urinary Tract Pathology

• Therapy

• References

The following sections are included:

• History

• Epidemiological Considerations
  • Factors Related to the Snails and Cercariae

• Infection and Reinfection with Schistosoma mansoni

• Early Phase or Acute Schistosomiasis
  • General Considerations
  • Patients in Permanent Contact with Focal Points of Infection
  • Patients in Sporadic Contact with Focal Points of Infection
  • Clinical Manifestations
  • Pathogenesis and Pathology

• Chronic Schistosomiasis
  • Intestinal and Hepatointestinal Form
  • Hepatosplenic Form
  • Importance
  • Characterization
  • Pathogeny of Simmers Fibrosis
  • Factors That Affect the Installation of Symmers Fibrosis
  • Factors Related to the Host
  • Host Predisposition
  • Genetic Markers
  • Complications of Hepatosplenomegaly
  • Pulmonary Hypertension
  • Cyanotic Syndrome
  • Peri-intestinal Fibrosis
  • Nephropathy
  • Other Clinical Forms
  • Morbid Associations
  • Other Morbid Associations

• Etiologic Diagnosis

• Clinical Diagnosis

• Treatment
  • Specific Treatment
  • Surgical Treatment

• References

The following sections are included:

• African Genesis

• Distribution and Changing Patterns of Infection
  • North Africa: Egypt and Sudan
  • East Africa: Ethiopia, Kenya, Uganda and Tanzania
  • West Africa: Togo, Nigeria, Cameroon, Benin, Sierra Leone, Liberia, Ghana, Cote d'lvoire, Senegal, Mali, Gambia, Guinea, Burkino Faso and Niger
  • Southern Africa: South Africa, Zimbabwe, Zambia, Botswana, Mozambique, Swaziland, Angola and Namibia
  • Central Africa: Chad, Central African Republic, Democratic Republic of the Congo, Burundi and Rwanda

• Morbidity
  • Acute Schistosomiasis
  • Hepatosplenic Disease and Periportal Fibrosis
  • Intestinal Schistosomiasis and Colonic Polyposis
  • Pulmonary Hypertension
  • Nephropathy
  • Neuroschistosomiasis
  • Dermatologic Lesions
  • Nutritional Deficits

• Control of Morbidity
  • Chemotherapy
  • Emergence of Drug Resistance
  • Snail Control
  • Obstacles to Control

• Topics for Further Research

• References

The following sections are included:

• Introduction

• Epidemiology

• Life Cycle

• Pathology

• Schistosomiasis at Community Level

• Clinical Stages

• Chronic Schistosomiasis Japonica
  • Hepatosplenic Form
  • Hepatointestinal Form
  • Pulmonary Form
  • Cerebral Form
  • Hematologic
  • Ectopic
  • Child Growth and Nutrition in Schistosomiasis Japonica
  • Diagnosis of Schistosomiasis Japonica
  • Chemotherapy

• References

The following sections are included:

• Introduction

• Schistosoma intercalatum
  • The Pathogen
  • Epidemiology
  • Pathology
  • Disease
  • Diagnosis
  • Therapy
  • Prevention

• Schistosoma mattheei
  • The Pathogen
  • Epidemiology and Disease
  • Diagnosis
  • Therapy

• Schistosoma bovis
  • The Pathogen
  • Epidemiology and Disease
  • Diagnosis
  • Therapy

• Other Zoonotic Schistosome Species in Africa That May Infect Humans

• Schistosoma mekongi
  • The Pathogen
  • Epidemiology
  • Pathology
  • Disease
  • Diagnosis
  • Therapy

• Schistosoma malayensis

• Other Rare Forms of Schistosomiasis in Asia

• Cercarial Dermatitis — "Swimmer's Itch"
  • Epidemiology
  • Disease
  • Pathology
  • Treatment
  • Prevention

• References

The following sections are included:

• Introduction

• Retrospect

• Assessing the Situation
  • Markers of Infection
  • Markers of Morbidity
  • The Snail Intermediate Host

• Chemotherapy
  • Mass Chemotherapy
  • Targeted Chemotherapy
  • Selective Population Treatment
  • Retreatment

• Snail Control
  • Molluscicides
  • Biological Control
  • Environmental Management
  • Water Resource Development

• Water Supply and Sanitation

• Health Education

• Economic Aspects

• Monitoring

• Current Control Strategies
  • North Africa
  • Central and Southern Africa
  • Latin America
  • The Middle East
  • The Far East

• Role of Research
  • Chemotherapy and Biochemistry
  • Diagnostics
  • Epidemiology
  • Operational Research
  • Vaccine Research
  • Snail Research
  • Research Support

• Novel Approaches, New Strategies

• References

The following sections are included:

• Rationale for Vaccine Development

• Potential Vaccination Approaches
  • Anti-infection Vaccines
  • Antifecundity Vaccines
  • Antipathology Vaccine
  • Transmission-Blocking Vaccine

• Insights from Clinical Studies
  • Natural and Naturally Acquired Resistance to Infection
  • Resistance to Reinfection Following Treatment
  • Preliminary Immune Correlate Studies with Defined Antigens

• Points to Consider for Vaccine Trials
  • Measures of Safety and Efficacy
  • Use of Vaccines in Control Programs
  • Testing an Antipathology Vaccine

• Practical Issues in Vaccine Development

• Caveats and Conclusions

• References

The following sections are included:

• Introduction

• Acquired Immunity in Humans

• Can Human Immunity Be Modeled in Experimental Animals?

• Nature of Protective Immune Mechanisms

• Pathogenesis in Experimental Models
  • Mechanistic Relationship Between Granuloma Formation and Fibrosis
  • Role of Thl vs. Th2 Cells in Pathogenesis

• What Causes the Down-modulation of Egg Pathology in Chronic Infection?

• What Stages of the Schistosome Life Cycle Should Be Targeted in a Human Vaccine?

• The Challenge

• References