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Case Studies in Infectious Disease: Echinococcus Spp PDF

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Echinococcus spp. Peter M. Lydyard Michael F. Cole John Holton William L. Irving Nino Porakishvili Pradhib Venkatesan Katherine N. Ward This edition published in the Taylor & Francis e-Library, 2009. To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk. Vice President: Denise Schanck Peter M. Lydyard, Emeritus Professor of Editor: Elizabeth Owen Immunology, University College Medical Editorial Assistant: Sarah E. Holland School, London, UK and Honorary Senior Production Editor: Simon Hill Professor of Immunology, School of Typesetting: Georgina Lucas Biosciences, University of Westminster, Cover Design: Andy Magee London, UK. Michael F. Cole, Professor Proofreader: Sally Huish of Microbiology & Immunology, Indexer: Merrall-Ross International Ltd Georgetown University School of Medicine, Washington, DC, USA. JohnHolton, Reader and Honorary ©2010 by Garland Science, Taylor & Francis Group, LLC Consultant in Clinical Microbiology, Windeyer Institute of Medical Sciences, University College London and University This book contains information obtained from authentic and highly College London Hospital Foundation Trust, regarded sources. Reprinted material is quoted with permission, and London, UK. William L. Irving, Professor sources are indicated. A wide variety of references are listed. and Honorary Consultant in Virology, Reasonable efforts have been made to publish reliable data and University of Nottingham and Nottingham information, but the author and the publisher cannot assume University Hospitals NHS Trust, responsibility for the validity of all materials or for the consequences of Nottingham, UK. Nino Porakishvili, their use. All rights reserved. No part of this book covered by the Senior Lecturer, School of Biosciences, copyright heron may be reproduced or used in any format in any form University of Westminster, London, UK or by any means—graphic, electronic, or mechanical, including and Honorary Professor, Javakhishvili photocopying, recording, taping, or information storage and retrieval Tbilisi State University, Tbilisi, Georgia. systems—without permission of the publisher. Pradhib Venkatesan, Consultant in Infectious Diseases, Nottingham University Hospitals NHS Trust, Nottingham, UK. The publisher makes no representation, express or implied, that the Katherine N. Ward, Consultant Virologist drug doses in this book are correct. Readers must check up to date and Honorary Senior Lecturer, University product information and clinical procedures with the manufacturers, College Medical School, London, UK and current codes of conduct, and current safety regulations. Honorary Consultant, Health Protection Agency, UK. ISBN 978-0-8153-4142-0 Library of Congress Cataloging-in-Publication Data Case studies in infectious disease / Peter M Lydyard ... [et al.]. p. ; cm. Includes bibliographical references. SBN 978-0-8153-4142-0 1. Communicable diseases--Case studies. I. Lydyard, Peter M. [DNLM: 1. Communicable Diseases--Case Reports. 2. Bacterial Infections--Case Reports. 3. Mycoses--Case Reports. 4. Parasitic Diseases-- Case Reports. 5. Virus Diseases--Case Reports. WC 100 C337 2009] RC112.C37 2009 616.9--dc22 2009004968 Published by Garland Science, Taylor & Francis Group, LLC, an informa business 270 Madison Avenue, New York NY 10016, USA, and 2 Park Square, Milton Park, Abingdon, OX14 4RN, UK. Visit our web site at http://www.garlandscience.com ISBN 0-203-85380-6 Master e-book ISBN Preface to Case Studies in Infectious Disease The idea for this book came from a successful course in a medical school setting. Each of the forty cases has been selected by the authors as being those that cause the most morbidity and mortality worldwide. The cases themselves follow the natural history of infection from point of entry of the pathogen through pathogenesis, clinical presentation, diagnosis, and treatment. We believe that this approach provides the reader with a logi- cal basis for understanding these diverse medically-important organisms. Following the description of a case history, the same five sets of core ques- tions are asked to encourage the student to think about infections in a common sequence. The initial set concerns the nature of the infectious agent, how it gains access to the body, what cells are infected, and how the organism spreads; the second set asks about host defense mechanisms against the agent and how disease is caused; the third set enquires about the clinical manifestations of the infection and the complications that can occur; the fourth set is related to how the infection is diagnosed, and what is the differential diagnosis, and the final set asks how the infection is man- aged, and what preventative measures can be taken to avoid the infection. In order to facilitate the learning process, each case includes summary bul- let points, a reference list, a further reading list and some relevant reliable websites. Some of the websites contain images that are referred to in the text. Each chapter concludes with multiple-choice questions for self-test- ing with the answers given in the back of the book. In the contents section, diseases are listed alphabetically under the causative agent. A separate table categorizes the pathogens as bacterial, viral, protozoal/worm/fungal and acts as a guide to the relative involve- ment of each body system affected. Finally, there is a comprehensive glos- sary to allow rapid access to microbiology and medical terms highlighted in bold in the text. All figures are available in JPEG and PowerPoint® for- mat at www.garlandscience.com/gs_textbooks.asp We believe that this book would be an excellent textbook for any course in microbiology and in particular for medical students who need instant access to key information about specific infections. Happy learning!! The authors March, 2009 Table of Contents The glossary for Case Studies in Infectious Disease can be found at http://www.garlandscience.com/textbooks/0815341423.asp Case 1 Aspergillus fumigatus Case 2 Borellia burgdorferi and related species Case 3 Campylobacter jejuni Case 4 Chlamydia trachomatis Case 5 Clostridium difficile Case 6 Coxiella burnetti Case 7 Coxsackie B virus Case 8 Echinococcus spp. Case 9 Epstein-Barr virus Case 10 Escherichia coli Case 11 Giardia lamblia Case 12 Helicobacter pylori Case 13 Hepatitis B virus Case 14 Herpes simplex virus 1 Case 15 Herpes simplex virus 2 Case 16 Histoplasma capsulatum Case 17 Human immunodeficiency virus Case 18 Influenza virus Case 19 Leishmania spp. Case 20 Leptospira spp. Case 21 Listeria monocytogenes Case 22 Mycobacterium leprae Case 23 Mycobacterium tuberculosis Case 24 Neisseria gonorrhoeae Case 25 Neisseria meningitidis Case 26 Norovirus Case 27 Parvovirus Case 28 Plasmodiumspp. Case 29 Respiratory syncytial virus Case 30 Rickettsiaspp. Case 31 Salmonella typhi Case 32 Schistosomaspp. Case 33 Staphylococcus aureus Case 34 Streptococcus mitis Case 35 Streptococcus pneumoniae Case 36 Streptococcus pyogenes Case 37 Toxoplasma gondii Case 38 Trypanosoma spp. Case 39 Varicella-zoster virus Case 40 Wuchereia bancrofti Guide to the relative involvement of each body system affected by the infectious organisms described in this book: the organisms are categorized into bacteria, viruses, and protozoa/fungi/worms Organism Resp MS GI H/B GU CNS CV Skin Syst L/H Bacteria Borrelia burgdorferi 4+ 1+ 1+ Campylobacter jejuni 4+ 2+ Chlamydia trachomatis 2+ 4+ 2+ Clostridium difficile 4+ Coxiella burnetti 4+ 4+ Escherichia coli 4+ 4+ 4+ 4+ Helicobacter pylori 4+ Leptospira spp. 4+ 4+ 4+ Listeria monocytogenes 2+ 4+ 2+ 4+ Mycobacterium leprae 2+ 4+ Mycobacterium tuberculosis 4+ 2+ Neisseria gonorrhoeae 4+ 2+ Neisseria meningitidis 4+ 4+ Rickettsia spp. 4+ 4+ 4+ Salmonella typhi 4+ 4+ Staphylococcus aureus 1+ 1+ 2+ 1+ 4+ 1+ Streptococcus mitis 1+ 4+ Streptococcus pneumoniae 4+ 4+ Streptococcus pyogenes 3+ 4+ 3+ Viruses Coxsackie B virus 1+ 1+ 4+ 1+ Epstein-Barr virus 2+ 4+ Hepatitis B virus 4+ Herpes simplex virus 1 2+ 4+ 4+ Herpes simplex virus 2 4+ 2+ 4+ Human immunodeficiency virus 2+ 2+ 4+ Influenza virus 4+ 1+ 1+ Norovirus 4+ Parvovirus 2+ 3+ 4+ 2+ Respiratory syncytial virus 4+ Varicella-zoster virus 2+ 2+ 4+ Protozoa/Fungi/Worms Aspergillusfumigatus 4+ 1+ 2+ Echinococcus spp. 2+ 4+ Giardia lamblia 4+ Histoplasmacapsulatum 3+ 1+ 4+ Leishmania spp. 4+ 4+ Plasmodium spp. 4+ 4+ Schistosoma spp. 4+ 4+ 4+ Toxoplasma gondii 2+ 4+ Trypanosoma spp. 4+ 4+ 4+ Wuchereria bancrofti 4+ The rating system (+4 the strongest, +1 the weakest) indicates the greater to lesser involvement of the body system. KEY: Resp = Respiratory: MS = Musculoskeletal: GI = Gastrointestinal H/B = Hepatobiliary: GU = Genitourinary: CNS = Central Nervous System Skin = Dermatological: Syst = Systemic: L/H = Lymphatic-Hematological Echinococcus spp. A 28-year-old Kurdish refugee complained of upper abdominal pain for 4 months. He had recently noticed some pain on the right side of his chest. He had not noticed any fever and his weight was stable. His doctor requested a chest X-ray. This showed a mass lesion in the right lung. He was referred to the Thoracic Surgical Department at the local hospital. A CT scan of his chest and abdomen was requested. This demonstrated a cystic structure in his liver, with another cyst in his chest (Figure 1). The surgeons excised the lung lesion. The histopathologists reported that it was a hydatid cyst. The patient was referred to the Infectious Diseases Department. A serological test was positive for Echinococcus. He was given treatment with albendazole and his remaining cyst was monitored serially on scans. Figure 1. Pulmonary hydatid cysts. Chest X-ray showing hydatid cysts (opaque areas at center right and center left) in a patient’s lungs. The cysts are caused by the parasitic tapeworm Echinococcussp. Humans are not a organ in the body. Large pulmonary cysts may cause natural host for the parasite, but may become infected from symptoms, including shortness of breath, chest discomfort ingesting eggs shed in the feces of an infected dog or other and sometimes wheeze. Treatment involves giving anti- canids. Cysts may be formed in the liver, lungs or any other parasitic drugs and careful surgical resection when possible. 1. What is the causative agent, how does it enter the body and how does it spread a) within the body and b) from person to person? Causative agent Echinococcusspecies are tapeworms, also known as cestodes. Adults are only 3–8.5 mm in length. Two species are responsible for the majority of human infections. Echinococcus granulosusarises from dogs and other canids and has been described worldwide. It causes cystic echinococcosis. Echinococcus multilocularis arises from arctic or red foxes and is restricted to the Northern Hemisphere. It causes alveolar echinococcosis. Infection with the latter seems to be spreading as red fox populations have been growing. Adult tapeworms live in the intestines of the dog or wild canid hosts. They attach to the mucosa with suckers and hooks. There are different parts to the structure of the tapeworm, and these are shown in Figure 2. The adult tapeworms lay eggs, which pass out in the feces and contaminate the soil. 2 ECHINOCOCCUS SPP. sucker uterus with eggs These may be swallowed by an intermediate host such as sheep for E. gran- ulosusand small mammals for E. multilocularis. Echinococcus granulosus Entry and spread within the body Humans are infected if they accidentally swallow eggs. The eggs have a Figure 2. An adult tapeworm of tough shell that breaks down and releases a larval form called the Echinococcus granulosus. oncosphere. The oncosphere burrows into the intestinal wall and then spreads to other parts of the body along blood vessels or lymphatics. The liver is the commonest site of infection as most of the intestinal drainage of blood is along the portal vein to the liver. However, infection could arise anywhere in the body. When the oncosphere lodges in an organ it develops into a vesicle. This progressively grows into a cyst. The cyst wall includes an inner germinal layer. From this buds a stage called protoscolex within brood capsules. Around the germinal layer is an acellular, laminated layer. For E. granulo- susthis cyst is unilocular and known as a hydatid cyst. For E. multilocularis the cyst is multilocular, or referred to as alveolar. Occasionally cysts can rupture giving rise to secondary, ‘daughter’ cysts. The structure of a hydatid cyst due to E. granulosus is shown in Figure 3. Person to person spread inflammatory cells germinal layer Humans do not spread Echinococcus spp. from person to person. Humans fibrosis acellular layer are an end host, with occasional exceptions. Figure 3. Histopathology of the Intermediate hosts structure of a hydatid cyst. Round Animals such as sheep or cattle may ingest E. granulosus eggs shed in dog protoscoleces are seen on the right. They feces. They can act as intermediate hosts. When sheep or cattle are killed, arise from a thin germinal layer, which is dogs may eat their meat or offal. When the dogs swallow cysts within surrounded by an acellular layer; the host infected tissues the protoscoleces are released. They attach to the dogs’ inflammatory cells can be seen to the left intestinal mucosa to mature into the adult tapeworms. Thus the life cycle of this. is completed (Figure 4). Dogs are the definitive hosts. This life cycle for E. granulosus occurs on farms but for E. multilocularis there is a rural, or sylvatic, life cycle with small mammals serving as the intermediate host and arctic or red foxes as the definitive host. Epidemiology Given the life cycle, hydatid disease is most common where dogs and ani- mals such as sheep and cattle mix. In the United Kingdom hydatid disease has been mainly found in sheep farming areas such as North Wales. Worldwide the Turkana district of Kenya has one of the highest incidences of human cystic echinococcosis. Dogs are a key part of Turkana commu- nities that herd cattle. The Turkana do not always bury their dead. Dogs may then scavenge human remains and continue the life cycle. 2. What is the host response to the infection and what is the disease pathogenesis? Potentially the host may mount a response to the oncospheres, after they have entered the intestine, or against the cysts, which become surrounded by the acellular, laminated layer. There may also be a host response to fluid that leaks from a ruptured cyst. ECHINOCOCCUS SPP. 3 6 scolex attaches to intestine 4 4 definitive host 1 adult in dogs and other canidae small intestine 4 2 5 protoscolex from cyst 4 ingestion of cysts (in organs) i 3 4 2 embryonated egg in feces ingestion of eggs (in feces) d intermediate hosts 4 hydatid cysts in sheep, goats, swine liver, lungs, etc. 3 oncosphere hatches: penetrates intestinal wall i infective stage d diagnostic stage Little is known of the host response to the oncospheres. A single or small Figure 4. Life cycle of Echinococcus number of oncospheres may not pose a sufficient antigenic stimulus to granulosus. Adult worms living in the dog trigger an adaptive immune response. The innate immune response, uti- intestine shed eggs in dog feces. These contaminate the environment and may be lizing phagocytic cells or complement, may attack them after invasion of ingested by intermediate hosts such as the intestinal mucosa. Once a hydatid cyst has developed an antibody sheep. In the intestine oncospheres hatch response occurs that is initially IgM followed by an IgG and IgE from the eggs and penetrate the intestinal response. If these antibodies also recognize the oncospheres they could wall. The oncosphere spreads to other play a part in preventing further ingested oncospheres from causing addi- organs and eventually matures into a cyst. tional infection. Within the cyst protoscolices develop. When a cyst is ingested by a dog the An inflammatory response occurs around the maturing cyst. This is trig- protoscolices are released, attach to the gered by complement activation. There is an infiltration of macrophages intestinal mucosa as a scolex, and mature and lymphocytes and these include both CD4+and CD8+T lymphocytes. into adult worms. Both Th1- and Th2-type cytokines are found, such as interferon (IFN)-gg, interleukin (IL)-4, and interleukin-10. Eventually a host- derived, fibrous layer forms around the cyst. Complement activation and inflammation subside as the acellular layer accumulates. It is thought that there is local immunomodulation with impaired macrophage responses, impaired dendritic cell differentiation, and T-regulatory cells. Cyst- derived antigens, including an antigen B, affect the maturation and func- tion of dendritic cells, such that when they present antigen to lymphocytes the immune response skews to a Th2 pattern. The latter is characterized by IL-4 production and increased IgG and IgE levels.

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