Clinical Parasitology: A Practical Approach PDF

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tahir99-VRG & vip.persianss.ir Clinical Parasitology tahir99-VRG & vip.persianss.ir YOU’VE JUST PURCHASED MORE THAN A TEXTBOOK ACTIVATE THE COMPLETE LEARNING EXPERIENCE THAT COMES WITH YOUR BOOK BY REGISTERING AT http://evolve.elsevier.com/Zeibig/parasitology Once you register, you will have access to your FREE STUDY TOOLS: Interactive Quizzes Questions for each chapter help test your knowledge of the content. REGISTER TODAY! tahir99-VRG & vip.persianss.ir Clinical Parasitology A PRACTICAL APPROACH Second Edition R G - V 99 s. ir h ir & ns ta r sia. pe vip Elizabeth A. Gockel-Blessing (formerly Zeibig), PhD, MLS(ASCP)CM Interim Associate Dean for Student and Academic Affairs Program Director, Master of Science in Health Sciences Associate Professor, Department of Clinical Laboratory Science Doisy College for Health Sciences Saint Louis University St. Louis, Missouri tahir99-VRG & vip.persianss.ir 3251 Riverport Lane St. Louis, Missouri 63043 CLINICAL PARASITOLOGY: A PRACTICAL APPROACH ISBN: 978-1-4160-6044-4 Copyright © 2013, 1997 by Saunders, an imprint of Elsevier Inc. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). R G - V 99 s. ir Notices ir & ns h ia research and experience ta Knowledge and best practice in this field are constantly changing. r Assnew treatment may become necessary.. pe practices, or medical broaden our understanding, changes in research methods, professional Practitioners and researchers must always rely on theirip v ownorexperience evaluating and using any information, methods, compounds, and knowledge in experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-1-4160-6044-4 Publishing Director: Andrew Allen Content Manager: Ellen Wurm-Cutter Publishing Services Manager: Julie Eddy Senior Project Manager: Marquita Parker Design Manager: Teresa McBryan Working together to grow libraries in developing countries Printed in China www.elsevier.com | www.bookaid.org | www.sabre.org Last digit is the print number: 9 8 7 6 5 4 3 2 1 tahir99-VRG & vip.persianss.ir For Bob tahir99-VRG & vip.persianss.ir  CONTRIBUTORS Charity E. Accurso, PhD, MT(ASCP) Michelle Mantooth, MSc, MLS(ASCP)CM, Assistant Professor CG(ASCP)CM Medical Laboratory Science Program MLT Instructor University of Cincinnati Trident Technical College Cincinnati, Ohio Charleston, South Carolina Hassan A. Aziz, PhD, MLS(ASCP)CM Lauren Roberts, MS, MT(ASCP) Director and Associate Professor Microbiology Laboratory Biomedical Sciences St. Joseph’s Hospital and Medical Center Qatar University Phoenix, Arizona Doha, Qatar John P. Seabolt, EdD, MT(ASCP)SM Lynda A. Britton, PhD, MLS(ASCP)CM SM Senior Academic Coordinator Program Director and Professor Department of Biology Program in Clinical Laboratory Sciences University of Kentucky Department of Clinical Sciences Lexington, Kentucky School of Allied Health Professions LSU Health Sciences Center Teresa A. Taff, MA, MT(ASCP)SM Shreveport, Louisiana Laboratory Manager and Program Director School of Clinical Laboratory Science Janice M. Conway-Klaassen, PhD, Mercy Hospital St. Louis MT(ASCP)SM St. Louis, Missouri Director, Clinical Laboratory Science University of Minnesota TEST BANK WRITER Minneapolis, Minnesota Janice M. Conway-Klaassen, PhD, Jill Dennis, EdD, MLS(ASCP)CM MT(ASCP)SM Associate Dean of Academic Operations Director, Clinical Laboratory Science Assistant Professor of Medical Laboratory University of Minnesota Science Minneapolis, Minnesota Thomas University Thomasville, Georgia Linda J. Graeter, PhD, MT(ASCP) Associate Professor Medical Laboratory Science Program University of Cincinnati Cincinnati, Ohio vi tahir99-VRG & vip.persianss.ir  REVIEWERS Thomas Betsy, DC Amy R. Kapanka, MS, MT(ASCP)SC Professor MLT Program Director Bergen Community College Hawkeye Community College Paramus, New Jersey Waterloo, Iowa Adjunct Professor Felician College Perthena Latchaw, MS, MLS(ASCP)CM Lodi, New Jersey MLT Program Director Adjunct Professor Seminole State College SUNY Rockland Community College Seminole, Oklahoma Suffern, New York Laura A. Mayer Dorothy M. Boisvert, EdD, MT(ASCP) Office Assistant Professor Doisy College of Health Sciences Department of Biology/Chemistry Office of the Dean Fitchburg State College Saint Louis University Fitchburg, Massachusetts St. Louis, Missouri Donna M. Duberg, MA, MS, MT(ASCP)SM Paula C. Mister, MS, MT, SM(ASCP) Vice-Chair, Assistant Professor Educational Coordinator and Clinical Clinical Laboratory Science Department Microbiology Instructor Doisy College of Health Sciences Medical Microbiology Saint Louis University Johns Hopkins Hospital St. Louis, Missouri Instructor, Biology Department Community Colleges of Baltimore County Alese M. Furnald, BS, MLS(ASCP)CM Pathogenic Microbiology Laboratory Clinical Laboratory Scientist and Instructor Microbiologist Stevenson University Harry S. Truman Memorial Veterans Hospital Baltimore, Maryland Columbia, Missouri Cynthia Parsons, MS, MT(ASCP) Lynne Hamilton, PhD, MT(ASCP) Program Director, Medical Laboratory Assistant Professor Technology Clinical Laboratory Science Program Northeast Texas Community College School of Allied Health Sciences Mt. Pleasant, Texas Texas Tech University Health Sciences Center Lubbock, Texas Lauren Roberts, MS, MT(ASCP) Microbiology Laboratory Katherine M. Hopper, MS, MT St. Joseph’s Hospital and Medical Center Vanderbilt University Medical Center Phoenix, Arizona Nashville, Tennessee Anne T. Rodgers, PhD, MT(ASCP) Retired Professor of Medical Technology Hendersonville, North Carolina vii tahir99-VRG & vip.persianss.ir viii REVIEWERS Wendy Warren Sweatt, MT(ASCP), MS, CLS Linda Layne Williford Pifer, PhD, SM(ASCP), Clinical Coordinator GS(ABB) Center for Professional, Career, and Technical Professor, Department of Clinical Laboratory Education Sciences Jefferson State Community College University of Tennessee Health Science Center Birmingham, Alabama Memphis, Tennessee Teresa A. Taff, MA, MT(ASCP)SM Michele B. Zitzmann, MHS, MLS(ASCP) Laboratory Manager and Program Director Associate Professor School of Clinical Laboratory Science Department of Clinical Laboratory Sciences Mercy Hospital St. Louis Louisiana State University Health Sciences St. Louis, Missouri Center New Orleans, Louisiana Valerie A. Watson, MS Department of Microbiology, Immunology & Cell Biology West Virginia University Morgantown, West Virginia tahir99-VRG & vip.persianss.ir  PREFACE ix PREFACE Parasitology is an important component of The location of this chapter has been moved clinical laboratory medicine. The results obtained from the last chapter in the book to the second through specimen examination for parasites, chapter of the book right after the introduction provide invaluable information regarding the discussion. An updated, where appropriate, lab- diagnosis and treatment of human disease. Track- oratory diagnosis section is incorporated under ing the epidemiology of such organisms as the discussion of each parasite. Second is that of well as establishing prevention mechanisms may accurate organism identification, which is para- be accomplished with the assistance of this mount to successful parasitology. To enhance information. proper organism identification, full-color photo- Although numerous advances in technology micrographs are now embedded within the have been developed during recent years, the tra- corresponding parasite discussions. Full-color ditional technique of manually processing and detailed line drawings, many of which are examining the samples both macroscopically and enlarged to show detail, with structures labelled, microscopically still occurs in select clinical set- where appropriate and updated “Typical Char- tings. It is critical that well-educated and highly acteristics at a Glance” tables have been added. trained individuals perform these procedures as Periodic references to other chapters, without well as read and interpret the results. Thus, the being redundant, are strategically placed in the goal of this second edition is to provide such text to assist the reader in quickly finding addi- information for students preparing for a career tional information. in laboratory medicine, for learners in related Several parasites deemed appropriate, primar- disciplines, which include parasitology, and for ily in the Arthropod Chapter (Chapter 13) have clinical practitioners. been added to this second edition. Under the This “learner friendly” text is designed to individual parasite descriptions concise informa- assist learners in both the didactic and laboratory tion is incorporated regarding life cycle notes, components associated with human clinical par- epidemiology, clinical symptomatology, treat- asitology. Students using this book will have the ment, prevention and control, and notes of opportunity to develop the skills necessary to interest and new trends, where appropriate. become proficient entry-level practitioners. Cur- Features such as side-by-side comparison rently practicing clinicians may also find this drawings and an entire chapter dedicated to book of use as both a reference at the bench and common artifacts and confusers (Chapter 12) as a mechanism for these individuals to review that were placed into the first edition are also and sharpen their skills. In alignment with included in this edition with revisions for clarity Elsevier standards, the term laboratory techni- made as appropriate. The introduction to each cians is used throughout the book when referring chapter is now known as a feature called “Focus- to practicing laboratorians. The term in this ing In,” whereas the summary of each chapter context does not refer to a specific level of prac- constitutes the section entitled “Looking Back.” titioner but rather to all practitioners. A series of chapter review questions and a case In order to accomplish the aforementioned study with questions for consideration comprise goal, the primary focus of this text is two-fold. the section at the end of appropriate chapters First is that assurance that proper diagnostic entitled “Test Your Knowledge.” laboratory techniques are employed when con- This second edition contains several addi- ducting parasitology testing. The major adjust- tional features worthy of mentioning that pertain ments/new features designed to address this to the book in general, to specific chapters, and/ component of the two-fold focus are as follows. or to individual parasite discussions. Learning ix tahir99-VRG & vip.persianss.ir x PREFACE objectives have been updated as appropriate for material for both students and instructors. Instruc- each chapter. A list of key terms is embedded tors have access to a test bank, PowerPoint slides, within each set of appropriate chapter objectives. and an electronic image collection featuring all the Each term is then bolded and defined in the images from the book. Students have access to chapter where it first appears. A comprehensive interactive quizzes which test them on the content alphabetized glossary is located at the back of from individual chapters. the book. The common disease/condition name(s) Every attempt has been made to ensure that associated with each pathogenic parasite appears this text is as accurate and as up-to-date as pos- below the pronunciation for quick and easy sible. As with every field of study, disagreements reference. and discrepancies exist about particular facts. This text provides a way of enhancing Parasitology is no exception. In select instances problem solving skills through the use of case where this was encountered, notations were studies, each identified as “Case Study: Under made in the text. It is important to point out here the Microscope,” as these abilities are critical to that in all such occurrences appropriate decisions the practice of laboratory and primary care on how to remedy these situations for the purpose medicine. Each appropriate chapter begins with of this book were reached primarily by consider- a case study based on the chapter content that ing views from content experts and my personal follows and contains questions for consider- clinical experience. ation. A second case study complete with patient This text was written to serve as a concise and history and symptomatology, pertinent labora- practical guide to clinical parasitology. It is not tory findings, drawings of the organism(s) intended to be exhaustive in nature. It is my present and a series of questions appears at the sincere hope that users of this text will find it end of each appropriate chapter. Periodic self- to be a positive learning experience as well as assessment questions, each of which is entitled enjoyable and helpful. I welcome comments and “Test Your Knowledge” and a set of review suggestions from students, educators and practi- questions have been incorporated into each tioners. After all, this text has been designed with chapter. Answers for both the chapter “Quick you in mind. Quiz” and review questions are located in the appendices located in the back of the book. Elizabeth A. Gockel-Blessing (formerly Zeibig) A new addition to this second edition is an Evolve website. This Evolve site provides free  ACKNOWLEDGMENTS xi ACKNOWLEDGMENTS First and foremost, I would like to thank all of PROJECT ASSISTANTS the individuals who helped in the preparing of Steve Fobian Bill Matthews the first and second edition manuscript for pub- Peg Gerrity, Illustrator Kelly Rhodes lication. Their roles in this project ranged from Ryan Gile Gail Ruhling typists and photographers, proofreaders, editors, Terry Jo Gile The late David Zeibig and content consultants. I would like to extend Shirley Gockel a special thanks to each chapter contributor who took time out of his/her busy schedule to I would like to extend thanks to Deaconess review the first edition chapters, revise and Health Systems for supplying select samples that update content as appropriate and incorporate were used to obtain photographs as well as the the new features into this second edition. The required equipment necessary to take all of the dedication, support, and enthusiasm of all of text photography. these individuals were instrumental in produc- ing both editions of this text. I apologize in STUDENT ASSISTANTS advance for those I may have inadvertently omitted. A sincere thank you to the Saint Louis University Department of Clinical Laboratory Science classes of 1994 and 1995 for their encourage- ment, support, and help. These students, listed below, were helpful in many ways, including PROJECT CONSULTANTS looking up organism pronunciations and creat- Peggy A. Edwards, MA, MT(ASCP) ing representative parasite drawings upon which Assistant Dean of Student and Academic Affairs, those in this text are based. In addition, informa- Retired tion from several of their research projects was Department of Clinical Laboratory Science incorporated into the manuscript and is cited in Saint Louis University the reference section. St. Louis, MO Beatrice Bernhart Michael P. Grady, Ph.D. Theresa Blattner Professor of Education Karen Casey Saint Louis University Toni Depue St. Louis, MO John Drury David Fulmer James A. Taylor, Ed.D. Deidra Hughes Director, School of Allied Health Sciences Tricia Konrad Northeast Louisiana University Luann Linsalata Monroe, LA Laura Murat Bharat Patel Eugene C. Wienke, M.D. Tracy Pitzer Pathologist/Microbiology Laboratory Director, Dawn Randles Retired Jennifer Shelley Deaconess Health Systems Munsok So St. Louis, MO Claro Yu xi xii ACKNOWLEDGMENTS effectively write sentences, paragraphs and SPECIAL THANK-YOUS papers. To my colleagues in the Saint Louis University To my medical technology instructor Avril Department of Clinical Laboratory Science over Bernsen, who gave me the opportunity to the years of undending support throughout the study Medical Technology (now known as development and revision process associated Clinical Laboratory Science) under her with both editions of this book. direction. To Dr. Michael Grady who served as my The late Ann Boggiano advisor and mentor during graduate school Hillary Daniel and served as an outside reviewer for the first Donna Duberg edition chapters in this book. Peggy Edwards, Retired To my mother, Shirley Gockel, and brother Uthay Ezekiel and sister-in-law, Fred and Juanita Gockel, Mona Hebert for their unending encouragement and Rita Heuertz support. Linda Hoechst To my husband, Bob Blessing who provided Kathy Humphrey unending love and support during the editing Tim Randolph and production stages of this second edition. Sharon Smith Thanks to him for taking care of numerous Carol Sykora tasks and in doing so opened up valuable Mary Lou Vehige, Retired time blocks for me to work on this project. Last, but by no means least, thanks to the entire Special thanks to following individuals who staff at Elsevier. Special thanks to Selma each in their own way contributed to one or both Kaszczuk and Rachael Kelly for their support editions of this book: and patience during the preparation of the first To my late grandmother Grace W. Hull, who edition and to Ellen Wurm-Cutter and Marquita spent countless hours teaching me, during Parker for guidance and assistance during the my formative years, the skills necessary to second edition process.  CONTENTS xiii CONTENTS CHAPTER 1 CHAPTER 6 INTRODUCTION 1 SELECT SPOROZOA: PLASMODIUM AND BABESIA 129 Plasmodium vivax 136 CHAPTER 2 Plasmodium ovale 141 SPECIMEN COLLECTION AND Plasmodium malariae 143 PROCESSING 14 Plasmodium falciparum 147 Plasmodium knowlesi 151 CHAPTER 3 Babesia microti 154 THE AMEBAS 41 Babesia divergens 154 Entamoeba histolytica 45 CHAPTER 7 Entamoeba hartmanni 51 MISCELLANEOUS PROTOZOA 159 Entamoeba coli 53 Entamoeba polecki 56 Balantidium coli 162 Endolimax nana 58 Isospora belli 165 Iodamoeba bütschlii 60 Sarcocystis species 168 Entamoeba gingivalis 63 Cryptosporidium parvum 170 Naegleria fowleri 65 Blastocystis hominis 172 Acanthamoeba species 68 Cyclospora cayetanensis 174 Microsporidia 176 Toxoplasma gondii 177 CHAPTER 4 Pneumocystis jiroveci (Pneumocystis THE FLAGELLATES 77 carinii) 182 Giardia intestinalis 80 CHAPTER 8 Chilomastix mesnili 86 THE NEMATODES 188 Dientamoeba fragilis 88 Trichomonas hominis 91 Enterobius vermicularis 192 Enteromonas hominis 92 Trichuris trichiura 195 Retortamonas intestinalis 94 Ascaris lumbricoides 197 Trichomonas tenax 96 Necator americanus 202 Trichomonas vaginalis 97 Ancylostoma duodenale 202 Strongyloides stercoralis 207 Trichinella spiralis 210 CHAPTER 5 Dracunculus medinensis 213 THE HEMOFLAGELLATES 104 Leishmania braziliensis complex 111 CHAPTER 9 Leishmania donovani complex 113 THE FILARIAE 222 Leishmania mexicana complex 116 Wuchereria bancrofti 225 Leishmania tropica complex 117 Brugia malayi 227 Trypanosoma brucei gambiense 120 Loa loa 229 Trypanosoma brucei rhodesiense 121 Onchocerca volvulus 231 Trypanosoma cruzi 123 Mansonella ozzardi 233 Trypanosoma rangeli 125 Mansonella perstans 235 xiii xiv CONTENTS CHAPTER 10 Spiders 305 THE CESTODES 239 Scorpions 307 Fleas 308 Taenia saginata 242 Flies 310 Taenia solium 242 Lice 312 Hymenolepis diminuta 247 Mosquitoes 314 Hymenolepis nana 249 Bugs 316 Dipylidium caninum 251 Diphyllobothrium latum 253 Echinococcus granulosus 256 APPENDIX A GLOSSARY 323 CHAPTER 11 THE TREMATODES 265 APPENDIX B Fasciolopsis buski 269 ANSWERS TO CASE STUDIES UNDER Fasciola hepatica 269 THE MICROSCOPE 333 Clonorchis sinensis 271 Heterophyes heterophyes 273 APPENDIX C Metagonimus yokogawai 273 ANSWERS TO QUICK QUIZ Paragonimus westermani 275 QUESTIONS 339 Schistosoma mansoni 277 Schistosoma japonicum 277 APPENDIX D Schistosoma haematobium 277 ANSWERS TO TEST YOUR KNOWLEDGE REVIEW QUESTIONS 343 CHAPTER 12 ARTIFACTS AND CONFUSERS 286 APPENDIX E BIBLIOGRAPHY 352 CHAPTER 13 THE ARTHROPODS 297 INDEX 355 Ticks 301 Mites 303  CHAPTER 1 Introduction Elizabeth Zeibig WHAT’S AHEAD Focusing In Disease Processes and Specimen Processing and Historical Perspective Symptoms Laboratory Diagnosis Epidemiology Treatment Parasite Nomenclature and Parasite-Host Relationships Prevention and Classification Parasitic Life Cycles Control Looking Back LEARNING OBJECTIVES On completion of this chapter, the successful Metazoa learner will: Micron (abbreviated as µ or µm; 1-1. Define each of the following key terms and pl., microns) phrases: Mode of transmission (pl., modes of Accidental or incidental host (pl., hosts) transmission) Animalia Mutualism Arthropod (pl., arthropods) Obligatory parasite Artifact (pl., artifacts) O&P Carrier (pl., carriers) Parasite (pl., parasites) Commensal Parasitic Commensalism Parasitic life cycle Confuser (pl., confusers) Parasitology Definitive host Parasitism Diagnostic stage (pl., stages) Pathogenic Disease Protozoa Ectoparasite Reservoir host Elephantiasis Symbiosis Endoparasite Transport host Epidemiology Vector (pl., vectors) Facultative parasite 1-2. Identify and summarize the key discoveries Helminth (pl., helminthes or helminths) that have contributed to current knowledge Host (pl., hosts) about parasites. Infection 1-3. Select the areas in the world in which Infective stage parasitic infections are endemic and Infestation the factors that contribute to their Intermediate host (pl., hosts) occurrence. Copyright © 2013 by Saunders, an imprint of Elsevier Inc. 1 2 CHAPTER 1 Introduction 1-4. Identify and describe the main factors 1-17. Summarize, in general terms, the that account for the increased prevalence components of the ova and parasite (O&P) of parasites in nonendemic areas of traditional parasite processing technique the world. performed on a variety of samples including 1-5. Choose populations of people at risk of stool. contracting a parasitic infection. 1-18. Give examples of newer parasite recovery 1-6. Identify and describe the primary modes of techniques. parasitic transmission. 1-19. State the name of each of the three 1-7. State the primary function of a host in a major groups of the clinically significant parasite-host relationship. parasites. 1-8. Explain, in general terms, the parasite-host 1-20. Differentiate Protozoa, Metazoa, and relationship. Animalia in terms of definition and the 1-9. Give an example of a parasite defense members of each group. mechanism that serves to protect it from a 1-21. Analyze case studies with information host’s immune system. pertinent to this chapter, and: 1-10. State the two common phases in the A. Interpret and explain the information, parasitic life cycle and the significance data and results provided. of each. B. Define and explain the parasite- 1-11. Identify and describe the key pieces of associated terms and processes information that may be extracted from associated with the case. each of the two common phases in the C. Construct a generic parasite life parasitic life cycle. cycle. 1-12. List the major body areas that may be D. Determine possible parasite-associated affected as the result of a parasitic epidemiology, generic, symptoms infection. and disease processes, treatment, 1-13. Name the most commonly observed and prevention and control symptoms associated with parasitic measures. infections. E. Explain the parasite-related processes 1-14. Cite examples of available treatment going on in the case. therapies to combat parasitic F. Propose subsequent actions to infections. be taken and/or solutions, with 1-15. Outline possible parasite prevention and justification. control strategies. G. Design an informational brochure that 1-16. Select the most commonly submitted contains generic information about all specimen type for parasitic study. or select aspects of parasites. CA S E S T U D Y 1 - 1 UNDER THE MICROSCOPE Joe, a third-year medical student, presented to his physi- 2. Indicate where Joe might have come into contact with cian complaining of severe diarrhea and abdominal pain parasites and identify the factors that likely contributed and cramping. Patient history revealed that Joe recently to this contact. (Objective 1-21D) returned home after a 3-month medical missionary trip to 3. Name two other populations that are at risk of contract- Haiti. Suspecting that Joe might be suffering from a para- ing parasitic infections. (Objective 1-21D) sitic infection, his physician ordered a battery of tests, 4. Name two other symptoms associated with parasitic including a stool sample for parasite examination using a infections that individuals like Joe may experience. traditional O&P technique. (Objective 1-21D) Questions and Issues for Consideration 5. What are the key components of a traditional O&P 1. What is a parasite? (Objective 1-21B) examination? (Objective 1-21B)  CHAPTER 1 Introduction 3 important. Advances in other areas of medical FOCUSING IN and biologic science, coupled with the discovery The purpose of this chapter is to introduce the of useful tools, such as microscopes, not only reader to the study of parasites, organisms that expanded our knowledge of parasites and their live on and obtain their nutrients from another makeup, but also their relationships with hosts— organism, a field known as parasitology. A brief that is, plants, animals, and humans known to historical perspective of this field is followed by harbor parasites. an introduction to epidemiology, the factors that Today, parasitologists and clinicians have a contribute to the frequency and distribution of wealth of parasite knowledge from which to parasites, parasite-host relationships, and para- draw. The escalation of disease caused by the sitic life cycles, defined as an examination of the presence of parasites (a concept known as para- route a parasite follows throughout its life. An sitic) because of global travel tends to result in introduction to disease processes and symptoms, higher parasite recovery rates. The increased treatment, and prevention and control associated number and diversity of these organisms may with parasites are presented. Specifics of these allow practitioners to gain high levels of exper- topics are discussed on an individual parasite tise in parasite identification and treatment. basis, as appropriate. Identification of the three Enhanced preservation of specimens now major groups of clinically significant parasites allows parasites that otherwise might have been follows a section that provides general informa- destroyed to remain viable. A number of advances tion regarding specimen processing and labora- in parasitology, particularly in the area of para- tory diagnosis of parasites, covered in more site laboratory diagnosis, promise to be exciting. detail in Chapter 2. Measures are also now in place that are designed to protect the practitioner when handling samples for parasite study. HISTORICAL PERSPECTIVE The documentation of parasite existence by the ancient Persians, Egyptians, and Greeks dates Quick Quiz! 1-1 back to prehistoric times. Just as the people of that era were primitive, relatively speaking, so Which of the following are key discoveries that too were parasites. Although underdeveloped contributed to current knowledge about parasites? areas still exist, humans have progressed through (Objective 1-2) the years into an age of civilization. Parasites A. Consistent status quo preservation of samples have evolved as well. B. Techniques that indicate only the presence or A number of discoveries over the years has absence of parasites contributed to our current knowledge of parasi- C. Modifications of traditional parasite identification tology. For example, as increased awareness that techniques parasites were becoming a problem and the real- D. Decrease in parasite incidence because of global ization that they were responsible for invasion in travel the body (infection), invasion on the body (infes- tation), and disease, defined as a process with EPIDEMIOLOGY characteristic symptoms, emerged, determining an effective means of healing infected persons Even though treatment, prevention, and control became a priority. As more information was dis- measures are available, parasitic infections still covered regarding parasitic life cycles, especially occur and thus it is important to study the fact that transport carriers known as vectors and monitor their trends, a field known as epi- were frequently responsible for transmission, demiology. Although they are distributed world- parasite control and elimination also became wide, most parasitic infections are found in 4 CHAPTER 1 Introduction BO X 1 - 1 Populations at Risk for BOX 1-2 Modes of Parasite Transmission Contracting Parasites Ingestion of contaminated food or drink (primarily water) Individuals in underdeveloped areas and countries Hand-to-mouth transfer Refugees Insect bite Immigrants Entry via drilling through the skin Visitors from foreign countries Unprotected sexual relations Individuals who are immunocompromised Mouth-to-mouth contact Individuals living in close quarters (e.g., prisons) Droplet contamination Children who attend day care centers Eye contact with infected swimming water underdeveloped tropical and subtropical coun- on to an uninfected host, most often via a blood tries such as Haiti, Guatemala, and Myanmar meal (bite). Still others will drill their way (Burma) and countries on the African continent. into the body via the skin through an unpro- Increased population den­sity, poor sanitation, tected bare foot or when an unsuspecting human marginal water sources, poor public health prac- is swimming in contaminated water. Sexual tices, and environmental changes affecting vector transmission, mouth-to-mouth contact through breeding areas account for the prevalence of para- kissing, droplet contamination, and eye contact sites. The habits and customs of the people living with infected swimming water also serve as in these regions are also contributing factors. routes for parasite transmission. The increased prevalence of global travel likely accounts for parasitic infections being spread to areas other than where these infections Quick Quiz! 1-2 originated. Individuals who travel to endemic Which of the following people may be at risk for areas are at risk of contracting parasitic infec- contracting a parasitic infection? (Objective 1-5) tions. Refugees, immigrants, and foreign visitors A. A toddler who attends an all-day preschool or day may bring parasites with them when entering a care center nonendemic area. B. A 25-year-old man who lives on his own in an Representative additional human populations apartment complex at risk of contracting a parasitic infection are C. A 37-year-old South American refugee listed in Box 1-1. Historically, a dramatic increase D. More than one of these: _______________ in parasite infection incidence occurred in the (specify) homosexual population but it is now also occur- ring more in the heterosexual population. More recently, parasitic infections have become more PARASITE-HOST RELATIONSHIPS prevalent in underdeveloped countries, regard- less of a person’s sexual orientation. The study of parasite-host relationships is over The means whereby a parasite gains entry into 100 years old. The main focus of this research an unsuspecting host, referred to as mode of has been threefold: (1) recognition of these rela- transmission, vary by specific parasite species tionships; (2) search for patterns of the relation- and those associated with the parasites covered ships; and (3) development of methodologies to in this text are summarized in Box 1-2. Consum- study these patterns. Table 1-1 lists the terms ing contaminated food or water and hand-to- associated with parasite-host relationships, along mouth transfer are common ways of transmitting with their definitions. select parasites. Others require an insect (arthro- There are several types of parasites that may pod) vector through which a parasite is passed be members of a parasite-host relationship. An  CHAPTER 1 Introduction 5 TA B L E 1 - 1 Terms Associated with Parasite-Host Relationships Parameter Definition or Description Type of Parasite Obligatory parasite Parasite that cannot survive outside of a host Facultative parasite Parasite that is capable of existing independently of a host Endoparasite Parasite that is established inside of a host Ectoparasite Parasite that is established in or on the exterior surface of a host Type of Host Accidental or incidental host Host other than the normal one that is harboring a parasite Definitive host Host in which the adult sexual phase of parasite development occurs Intermediate host Host in which the larval asexual phase of parasite development occurs Reservoir host Host harboring parasites that are parasitic for humans and from which humans may become infected Transport host Host responsible for transferring a parasite from one location to another Carrier Parasite-harboring host that is not exhibiting any clinical symptoms but can infect others Parasite-Host Relationship Terms Symbiosis Living together; the association of two living organisms, each of a different species Commensalism Association of two different species of organisms that is beneficial to one and neutral to the other Mutualism Association of two different species of organisms that is beneficial to both Parasitism Association of two different species of organisms that is beneficial to one at the other’s expense Commensal Relating to commensalism; the association between two different organisms in which one benefits and has a neutral effect on the other Pathogenic Parasite that has demonstrated the ability to cause disease organism may be an obligatory parasite or a the host’s immune system. Parasites alter their facultative parasite. It may be an endoparasite or antigenic makeup so that the host will not reco­ an ectoparasite. In the same manner, a number gnize the modified parasites as foreign, and thus of different hosts may be part of this parasite- the initiation of an immune response does not host relationship. These include accidental or occur. A more in-depth study of parasite-host incidental hosts, definitive hosts, intermediate relationships is beyond the scope of this chapter. hosts, reservoir hosts, transport hosts, and Where appropriate, further consideration of this carriers. topic is discussed on an individual parasite basis. When a parasite infects a host, symbiosis results. The primary function of the host is to carry on the parasite’s life cycle. This newly formed relationship may develop into commen- Quick Quiz! 1-3 salism, mutualism, or parasitism. Some of these associations exist as commensal under certain The primary function of a host in a parasite-host circumstances and pathogenic under others. relationship is to: (Objective 1-7) Parasites have an amazing capability to adapt A. Carry on the parasite’s life cycle. to their host surroundings. In addition to a B. Provide immunologic protection for the host. number of morphologic adaptations, parasites C. Carry on the host’s life cycle. are capable of protecting themselves from D. Provide a food source for the host. 6 CHAPTER 1 Introduction A parasitic life cycle consists of two common PARASITIC LIFE CYCLES phases (Fig. 1-1). One phase involves the route a Although parasitic life cycles range from simple parasite follows when in or on the human body. to complex, they all have three common This information provides an understanding of components—a mode of transmission, a mor- the symptomatology and pathology of the para- phologic form that invades humans, known as site. Insights about the best the method of diag- the infective stage, and one (or more) forms that nosis and selection of appropriate antiparasitic can be detected via laboratory retrieval methods, medication may also be determined. The other known as the diagnostic stage. Some parasites phase, the route a parasite follows independently require only a definitive host, whereas others also of the human body, provides crucial information require one or more intermediate hosts. pertinent to epidemiology, prevention, and control.  Parasites come in contact with human Parasites emerge Parasites enter from water, food, soil, and establish residence Ro intermediate hosts in or on human ut Ro [Infective stage(s)] e a ut pa e a ra pa sit ra e sit fo llo e fo ws llo in ws Parasites come sid in  in contact with e de or Parasites multiply pe soil or water, on and compete with nd intermediate hu en human for m food hosts to an nutritional needs fa bo hu dy m an Parasites enter outside environment Parasites emerge from human (diagnostic stages) Key  Parasite  Water  Representative intern host  Human  Food  Morphologic changes occur as appropriate FIGURE 1-1 Generic parasite life cycle.  CHAPTER 1 Introduction 7 Quick Quiz! 1-4 diarrhea, fever, chills, abdominal pain, and abdominal cramping. Other symptoms, such as Which of the following key pieces of information may elephantiasis (an enlargement of areas such as be extracted from the portion of a parasite’s life cycle the breast, leg, and scrotum caused by a para- that occurs outside the body? (Objective 1-11) site’s presence), anemia, vitamin deficiency, bowel A. Parasitic disease symptoms and disease processes obstruction, edema, enlargement of major organs, B. Epidemiology and prevention and control skin lesions, and blindness, may develop. measures C. Appropriate parasite diagnosis methodologies D. Selection of appropriate antiparasitic medication Quick Quiz! 1-5 Which of the following groups of symptoms repre- DISEASE PROCESSES sents those most commonly observed in parasitic AND SYMPTOMS infections? (Objective 1-13) A parasitic disease may affect the entire body or A. Diarrhea, abdominal cramping, and anemia any of its parts. The major body areas associated B. Enlargement of the spleen, fever, and chills with such processes include the following: (1) the C. Skin lesions, abdominal pain, and diarrhea gastrointestinal (GI) and urogenital (UG) tracts; D. Abdominal cramping, abdominal pain, and (2) blood and tissue; (3) liver, lung, and other diarrhea major organs; and (4) miscellaneous locations, such as cerebrospinal fluid (CSF), eye, skin, and extremities. TREATMENT A wide variety of representative symptoms, summarized in Box 1-3, may occur when a para- There are several options for treating parasitic site infects a human host. Some persons remain infections. Examples of such measures are listed asymptomatic, whereas other parasites produce in Box 1-4. There are a variety of antiparasitic severe symptoms and may result in death. The medications available. Many of these drugs are most commonly observed symptoms include toxic to the host and care should be exercised when selecting the proper course of treatment. Therapies such as a change in diet, vitamin supplements, fluid replacement, blood transfu- BOX 1-3 Symptoms Associated with sion, and bed rest may be indicated solely or in Parasitic Disease Processes addition to chemotherapy. Treatment for non- Diarrhea pathogenic parasitic infections is usually not Fever indicated. Chills Abdominal pain Abdominal cramping Elephantiasis BOX 1-4 Parasite Treatment Options Anemia Vitamin deficiency Antiparasitic medications Bowel obstruction Change in diet Edema Vitamin supplements Enlargement of major organs Fluid replacement Skin lesions Blood transfusion Blindness Bed rest 8 CHAPTER 1 Introduction Quick Quiz! 1-6 Quick Quiz! 1-7 Which of the following represent examples of avail- Which of the following are examples of possible able treatment therapies to combat parasitic infec- parasite prevention and control measures? tions? (Objective 1-14) (Objective 1-15) A. Regulated exercise plan A. Avoiding the use of insecticides B. Change in diet B. Practicing unprotected sex C. Avoidance of vitamin supplements C. Practicing proper sanitation practices D. More than one of these: ______________ (specify) D. More than one of these: ________________ (specify) PREVENTION AND CONTROL Prevention and control measures may be taken SPECIMEN PROCESSING AND against every parasite infective to humans. Pre- LABORATORY DIAGNOSIS ventive measures designed to break the transmis- sion cycle are crucial for successful parasite Proper specimen selection and processing are eradication. Examples of such measures are listed crucial to parasite recovery. There are a variety in Box 1-5 and include the following: education of acceptable specimen types that may be exam- programs, use of insecticides and other chemi- ined for parasites. Stool is the most commonly cals, protective clothing, protective netting, submitted sample for such studies. Typical stool proper water treatment, good personal hygiene, analysis consists of performing macroscopic and proper sanitation practices, proper handling and microscopic techniques on a portion of unpre- preparation of food, and avoidance of unpro- served sample when available. A process to tected sexual relations. The vast capital expendi- remove fecal debris, which often resembles tures required to accomplish these measures are parasitic forms, is performed on a portion of not available in many endemic countries in the sample after a preservative is added to it. Micro- world. The problem of eradicating parasites is an scopic analysis of the resultant processed ongoing process and is a key goal of interna- sample follows. This traditional parasite recov- tional health groups such as the World Health ery method, often referred to as an O&P, in Organization (WHO) and Doctors Without which “O” stands for ova (eggs) and “P” stands Borders (Médecins Sans Frontières [MSF]). for parasites, is still widely used today. Other specimens, including blood, tissue biop- sies, CSF, sputum, urine, and genital material, may also be examined for the presence of para- BO X 1 - 5 Parasite Prevention and sites. In some cases, the sample is basically pro- Control Strategies cessed the same as for stool. Other specimens, Development and implementation of parasite awareness such as blood, are traditionally processed differ- education programs ently. For example, a Giemsa stain followed by Use of insecticides and other chemicals microscopic examination is the procedure of Use of protective clothing choice for blood samples submitted for parasite Use of protective netting study. Proper water treatment A number of other traditional and new para- Good personal hygiene site recovery techniques are available. Cello- Proper sanitation practices phane tape preparation, a methodology for Proper handling, cooking, and protection of food Avoidance of unprotected sexual relations recovery of pinworm eggs, and the Enterotest (string test) for recovery of several parasites are  CHAPTER 1 Introduction 9 nuclear structures, although very different on BOX 1-6 Newer Parasite Laboratory Diagnosis Techniques further inspection, may often initially appear almost identical. Plant cells, as another example, Direct fluorescent antibody (DFA) resemble the Ascaris lumbricoides egg (see Enzyme immunoassay (EIA) Chapter 8 for details), a member of the subking- Indirect fluorescent antibody (IFA) dom Metazoa, which includes multicellular Latex agglutination (LA) organisms such as parasitic worms. Not only do Polymerase chain reaction (PCR) they share structural similarities, but both may Rapid immunochromatography technique measure in the diameter range of 30 to 50 µm. There are numerous artifacts and confusers (also often referred to as pseudoparasites) that may be among the traditional tests. Representative newer present in samples submitted for parasite study. methodologies are listed in Box 1-6. Details Brief detailed descriptions of a select group of regarding these various specimen processing commonly encountered artifacts and confusers techniques are found in Chapter 2, “Specimen are discussed in Chapter 12. Collection and Processing.” It is important to note that Chapter 2 was designed to provide Quick Quiz! 1-8 representative examples of laboratory method- ologies that may be used to recover parasites. Which of the following specimen type is most often In some cases, Chapter 2 contains laboratory submitted for parasite study? (Objective 1-16) methodologies that are not covered in the cor- A. Blood responding individual parasite laboratory diag- B. Sputum nosis sections. Similarly, the laboratory diagnosis C. Urine section of select individual parasites mentions D. Stool additional possible laboratory techniques that are not specifically identified as being associated PARASITE NOMENCLATURE AND with these parasites or are not mentioned at all CLASSIFICATION in Chapter 2. Thus, examination and study of the methods covered in Chapter 2 and those The scientific names of parasites are written in identified in the individual parasite laboratory italics and consist of two components, genus (pl., diagnosis sections are required to understand genera) and species. An example of a parasite and appreciate fully the extent of laboratory name is Giardia intestinalis (covered in detail techniques available. in Chapter 4), in which Giardia is the genus Careful and thorough microscopic examina- name and intestinalis is the species name. When tion of samples for parasites is essential to ensure a parasite name first appears in a document, the that accurate patient results are obtained and entire parasite name is written out. Subsequent ultimately reported. Suspicious forms that visu- references to a parasite are often abbreviated ally resemble parasites in terms of size and mor- by recording only the first letter of the genera phology are commonly encountered and are name followed by a period, followed by the often referred to as artifacts and/or confusers. entire species name. Thus, the abbreviation of For example, the Entamoeba histolytica cyst our example parasite Giardia intestinalis is (described in detail in Chapter 3), a single-celled G. intestinalis. eukaryotic animal known as a protozoa, typi- Variations of scientific genus names are used cally measures 12 to 18 microns (µm), a mea- to identify diseases and conditions associated surement defined as one millionth of a meter with their presence. The suffix -iasis is often used (10−6 m). Similarly, polymorphonuclear leuko- to denote such diseases or conditions. For cytes average 15 µm in size. In addition, the example, giardiasis refers to the disease or 10 CHAPTER 1 Introduction Subphylum Class Species Sarcodina Lobosea (amebas) See Chapter 2 Phylum Sarcomastigophora Subphylum Class Species Mastigophora Zoomastigophora See Chapters 3 and 4 (flagellates/hemoflagellates) Subkingdom Phylum Class Species Protozoa Ciliophora Kinetofragminophorea See Chapter 6 (ciliates) Order Class Species Blastocystida Blastocystea See Chapter 6 Phylum Class Species Apicomplexa Sporozoa See Chapters 5 and 6 FIGURE 1-2 Parasite classification—the protozoa. Class Species Nematoda See Chapter 7 Phylum (roundworms) Nemathelminthes Class Species Filariae See Chapter 8 Subkingdom (tissue roundworms) Metazoa Class Species Cestoda See Chapter 9 Phylum (tapeworms) Platyhelminthes Class Species Trematoda See Chapter 10 (flukes) FIGURE 1-3 Parasite classification—the helminths. condition associated with Giardia intestinalis. In amebas (Chapter 3). When appropriate, refer- some cases, a variation of a scientific genus name ence to the amebas may be written in several may be used to refer to a genus of parasites. Here ways, such as amebic or ameboid. is an example of this use of a genus name. There are several different parasite classifica- Chapter 5 of this text discusses two genera of tion systems, ranging from very basic to complex. parasites, Leishmania and Trypanosoma. In The system used in this text delineates three general, reference to infections with these two major groups of clinically significant parasites: genera is often written as leishmanial infections 1. Single-celled parasites—Protozoa (Fig. 1-2) and trypanosomal infections. 2. Multicellular worms—Metazoa helminths Along with specific parasite name variations, (Fig. 1-3) variations of parasite category names are 3. Arthropods (insects and their allies)—Anima- common. An example of this terminology is the lia (Fig. 1-4)  CHAPTER 1 Introduction 11 Class Crustacea (crabs, crayfish, etc.) Kingdom Phylum Class Species Animalia Arthropoda Arachnida See Chapter 12 (ticks, mites, etc.) Class Species Insecta See Chapter 12 (insects) Class Chilopoda (centipedes) Class Pentastomida (tongueworms) FIGURE 1-4 Parasite classification—the arthropods. The groups of parasites in each classification of parasites. In addition, parasites are classified table are organized by kingdom and subking- based on their individual characteristics. Tradi- dom, phylum and subphylum, and class. The tional as well as new methodologies for parasite individual species are classified in their respective identification allow for accurate laboratory chapters. diagnosis. Parasitology is an interesting and exciting field Quick Quiz! 1-9 of the clinical laboratory sciences. The continued development of high-tech, highly sensitive para- Which of the following correctly represents the three site test methodologies provides the key to the major groups of clinically significant parasites? (Objec- future of parasitology. Because it is highly tive 1-20) unlikely that parasites will totally be eradicated A. Protozoa—worms; Metazoa—single-celled para- in the near future, competent practitioners edu- sites; Arthropods—insects and their allies cated in the field of parasitology are essential to B. Protozoa—insects and their allies; Metazoa— ensure proper parasite identification. worms; Arthropods—single-celled parasites C. Protozoa—single-celled parasites; Metazoa— TEST YOUR KNOWLEDGE! worms; Arthropods—insects and their allies D. Protozoa—single-celled parasites; Metazoa— 1-1. Match each of the key terms (column A) insects and their allies; Arthropods—worms with its corresponding definition (column B). (Objective 1-1) LOOKING BACK Column A Column B Over the years, parasites once considered com- ___ A. Ectoparasite 1. The form of a mensal have evolved to become human patho- parasite that gens. During this time, we have gained tremendous enters a host knowledge of the epidemiology, parasite-host ___ B. Obligatory 2. Two organisms of relationships, life cycles, disease processes and parasite different species symptoms, treatment, and prevention and control living together 12 CHAPTER 1 Introduction Column A Column B 1-3. Why is there an increased prevalence of ___ C. Infective stage 3. The official units parasites in nonendemic areas of the of parasite world (Objective 1-4) measurement 1-4. What are some of the primary modes of ___ D. Commensalism 4. A parasite that parasitic transmission? (Objective 1-6) cannot survive 1-5. Suppose that you have been asked to outside its design a one-page informational flyer on host parasite-host relationships. Identify the ___ E. Disease 5. An insect that types of parasites, hosts, and parasite-host transports a relationships that you should include in parasite from an your flyer. (Objective 1-8) infected host to A. Types of parasites an uninfected B. Types of hosts host C. Types of parasite-host relationships ___ F. Microns 6. A parasite that Optional activity: Design the actual flyer and lives on the share with classmates. (Objective 1-21) outside surface of 1-6. Give one example of a parasite defense its host mechanism that serves to protect it from a ___ G. Transport host 7. Parasite-harboring host’s immune system. (Objective 1-9) host that is not 1-7. What are the two common phases of a affected by its parasitic life cycle? (Objective 1-10) presence but can 1-8. Refer to question 1-7. What key pieces of shed the parasite information may be extracted from each and infect of the two common phases of a parasitic others life cycle? (Objective 1-11) ___ H. Vector 8. A destructive 1-9. Which of the following major body areas process that has may be affected as the result of a parasitic characteristic infection? (Objective 1-12) symptoms A. Gastrointestinal tract ___ I. Symbiosis 9. Association of B. Respiratory tract two different C. Blood and tissue species of D. Liver and lung organisms that is E. More than one of these: ___________ beneficial to one (specify) but neutral to the 1-10. Which of the following are examples of other newer parasite recovery techniques? (Objec­ ___ J. Carrier 10. A host tive 1-18) responsible for A. Carbohydrate immunoassays transferring a B. RNA hybridization techniques parasite from one C. PCR location to D. Immunochromatographic techniques another E. More than one of these: _______________ (specify) 1-2. In what parts of the world are parasites 1-11. What are the three groups of clinically endemic, and what factors contribute significant parasites? (Objective 1-19) to their occurrence in these areas? (Objec- 1-12. Suppose you are asked to speak to a group tive 1-3) of grade school–aged children who are  CHAPTER 1 Introduction 13 preparing to go on a class picnic. The detailed, written at a grade school level. students are currently learning the basics (Objective 1-21) about parasites in their science class. You 1-14. Suppose that you and a friend are studying have been asked to speak about possible for parasitology class together. Your friend parasite prevention and control strategies is having great difficulty visualizing the for the upcoming class outing. What strat- concept of parasite life cycles, including egies would you discuss with these stu- the difference between the two common dents? (Objective 1-21) phases and the information derived from 1-13. Refer to question 1-12. The session each phase. Your friend has asked you for with the students went so well that the help. Using Figure 1-1 as a guide, con- teacher would like you to take this struct your version of a generic parasite project to the next level. Design an infor- life cycle in a format that is easy to read mational brochure with these strategies and follow. (Objective 1-21) CHAPTER 2 Specimen Collection and Processing Lauren Roberts and Elizabeth Zeibig WHAT’S AHEAD Focusing In Other Intestinal Specimens Reporting of Results and Stool for Ova and Parasite Other Specimens and Quality Control Examination Laboratory Techniques Looking Back Stool Screening Methods Immunologic Testing LEARNING OBJECTIVES On completion of this chapter and review of its 2-3. Identify the procedures included in a tables and ocular micrometer diagram, the routine O&P examination. successful learner will: 2-4. Discuss the basic composition, purpose, 2-1. Define the following key terms: advantages, and disadvantages of each of Concentration technique (pl., techniques) the following preservatives and state which Concentrated iodine wet preparation laboratory procedures can be performed (pl., preparations) using each type: Concentrated saline wet preparation A. Formalin Concentrated wet preparation B. Polyvinyl alcohol (PVA) Direct iodine wet preparation C. Sodium-acetate formalin (SAF) Direct saline wet preparation D. Modified PVA Direct wet mount (pl., mounts) E. Alternative single-vial systems Direct wet preparation 2-5. Describe the characteristics of the Fixative (pl., fixatives) macroscopic examination of stool Micron (pl., microns; abbreviated µ or µm) specimens. O&P 2-6. Identify the procedures involved in the Ocular micrometer microscopic examination of stool Ova and parasites specimens. Permanent stained smear (pl., smears) 2-7. State the purpose and procedure involved Preparation, prep (pl., preparations; when calibrating and using an ocular abbreviated as preps) micrometer. Unfixed 2-8. Describe the use of a direct wet 2-2. Identify and describe the proper collection preparation and state when this procedure and transport of stool samples for parasitic can be eliminated from an O&P study. examination. 14 Copyright © 2013 by Saunders, an imprint of Elsevier Inc.  CHAPTER 2 Specimen Collection and Processing 15 2-9. State the purpose of concentration 2-15. Match the specific immunologic tests techniques and, for each technique studied, available with the parasite(s) that they can list the advantages and disadvantages. detect. 2-10. Explain the purpose of a permanent stained 2-16. Briefly describe the new techniques that smear and summarize the characteristics of have been developed for parasite study. the stains presented. 2-17. Identify and describe the appropriate 2-11. Describe the use of stool screening methods information to include in the parasitology and provide an example when these test report. methods would be used. 2-18. Identify the appropriate areas to be 2-12. Explain the purpose of examining intestinal included in a parasitology quality assurance specimens other than stool for parasites. program. 2-13. Describe the purpose, advantages, and 2-19. Analyze case studies with information disadvantages of performing the proper pertinent to this chapter and do the techniques for examining specimens other following: than stool and intestinal samples for the A. Interpret and explain the information, presence of parasites. data, and results provided. 2-14. Describe the use of immunologic tests for B. Propose subsequent actions to be taken the diagnosis of parasitic diseases and and/or solutions, with justification. provide an example when antibody testing might be used. CASE STUDY 2-1 UNDER THE MICROSCOPE MP, a 26-year-old man, returned home from a spring ski Questions for Consideration trip to the Rocky Mountain region and began to experience 1. Which tests should the laboratory technician intestinal unease, with nausea and abdominal fullness. He recommend to detect the presence of parasites? (Objec- then developed abdominal cramping and diarrhea, along tive 2-19B) with hives. MP became concerned when the symptoms 2. Describe the proper collection and transport of stool continued beyond 1 week, and he presented to his family samples for intestinal parasites. (Objective 2-2) physician. The physician decided to order laboratory tests 3. List the procedures that would be included in the routine to determine the cause and ordered a stool for culture and O&P examination. (Objective 2-3) sensitivity. The results indicated “no Salmonella, Shigella, 4. Suppose that the laboratory technician suggests that a E. coli O:157, or Campylobacter isolated.” On receiving stool screen be performed initially and, if the results are these results, the physician called the laboratory and negative, then a complete O&P is indicated. Explain this inquired about a workup for intestinal parasites. recommendation. (Objective 2-11) such as the United States. These diseases are usually brought about by climate conditions FOCUSING IN desirable for parasitic survival as well as poor As noted in Chapter 1, parasitic diseases con- sanitation and personal hygiene practices of the tinue to be a significant threat throughout the inhabitants. Certain populations are more at risk world. Although they appear to be more preva- of contracting parasitic infections, including lent in underdeveloped tropical and subtropical foreign visitors and those traveling and emigrat- countries, parasites do occur in developed areas, ing to other countries. 16 CHAPTER 2 Specimen Collection and Processing In areas in which parasitic infections are not blood, and body fluids; immunologic testing; considered a major cause of human disease, it future methods; and the reporting of results and can be difficult for health care professionals to quality control associated with parasite studies. recognize that these agents may be a cause of A concise but comprehensive discussion of the patient’s clinical condition. However, with each topic follows. This chapter contains the increased number of populations at risk for terminology that is detailed in other chapters contracting parasitic infections, it is critical in this text. Reference to the appropriate for clinicians to obtain knowledge of the clini- chapter is made where each appropriate term cal manifestations of parasitic diseases and first appears. understand the appropriate laboratory test(s) to order. Furthermore, laboratory technicians must have an understanding of these diseases STOOL FOR OVA AND to guide the physician in selecting the appropri- PARASITE EXAMINATION ate tests. Because the diagnosis of these diseases can be challenging and is not always straight- Without a doubt, the most common procedure forward, it is imperative that strong communi- performed in the area of parasitology is the cation exist between the physician and clinical examination of a stool specimen for ova and laboratory. parasites (abbreviated as O&P), where ova refers This chapter is designed to introduce readers to the egg stage of select parasites and parasites to representative testing methods available for encompasses the other morphologic forms that the diagnosis of parasitic infections. Parasites may be present. There are two general compo- that may be determined using these testing nents associated with this routine parasitology methods are identified. These lists are not procedure macroscopic and microscopic exami- intended to be exhaustive in nature. By design, nation. The microscopic examination consists of appropriate testing methods are mentioned in three possible components, each of which is the specific parasite laboratory diagnosis sec- detailed in the sections that follow a discussion tions, which may or may not be noted in this of collection, transport, and fixatives for preser- chapter. vation. As in all areas of laboratory testing, the Successful laboratory identification of para- quality of the results is dependent on the appro- sites requires the knowledge and practice of labo- priate collection of the specimen. ratory testing in the preanalytic, analytic, and postanalytic steps. For example, in the preana- lytic phase, a specimen received in the laboratory Collection and Transport that is compromised because of improper collec- tion, labeling, or transport should be rejected Morphologic forms of protozoa and helminths and a new specimen requested. Similarly, labora- may be detected from a properly collected and tory techniques performed in the analytic phase prepared stool specimen. When present, the pro- of testing of these samples should be completed tozoan forms known as trophozoites and cysts with care to ensure that accurate results are (discussed in more detail in Chapter 3) may be obtained. Interpretation and reporting of results recovered from these samples. Helminth stages, obtained, completed in the postanalytic phase of such as eggs, larvae, proglottids, and adult testing, should be accurately reported in a timely worms, may also be found. Definitions of these manner. helminth-related morphologic forms are detailed Specific topics addressed in this chapter in the corresponding parasite chapters of this include the following: specimen collection and text (Chapters 8 to 11). handling guidelines for stool and intestinal spec- Because parasites are often shed (i.e., imens; other specimen types, including tissue, enter and subsequently passed in the stool)  CHAPTER 2 Specimen Collection and Processing 17 intermittently, they may not appear in a stool specimen should be separated from the specimen specimen on a daily basis; therefore, multiple container. specimens are recommended for adequate detec- When handling all specimens, gloves and a tion. The typical stool collection protocol con- protective coat should be worn at all times. sists of three specimens, one specimen collected Biohazard hoods should also be used in labora- every other day or a total of three collected in 10 tories, when present. Universal precautions, as days. One exception is in the diagnosis of ame- outlined by the Occupational Safety and Health biasis (Chapter 3), in which up to six specimens Administration (OSHA) for handling blood and in 14 days is acceptable. body fluids, should be exhibited and enforced at Certain medications and substances may all times. interfere with the detection of parasites. Stool Another important consideration in testing samples from patients whose therapy includes fecal specimens for parasites is the time frame barium, bismuth, or mineral oil should be col- from sample collection to receipt and examina- lected prior to therapy or not until 5 to 7 days tion in the laboratory. To demonstrate the motil- after the completion of therapy. If the samples ity of protozoan trophozoites, a fresh specimen are taken during the course of therapy, these is required. The trophozoite stage is sensitive to interfering substances may mask possible para- environmental changes and, on release from the sites during examination. Collection of speci- body, disintegrates rapidly. Other parasite stages mens from patients who have taken antibiotics (e.g., protozoan cysts, helminth eggs and larvae) or antimalarial medications should be delayed are not as sensitive and can survive for longer for 2 weeks following therapy. periods outside the host. Because trophozoites Stool specimens should be collected in a clean, are usually found in liquid stool, it is recom- wa