LECTURE NOTES For Medical Laboratory Technology Students Parasitology Girma Mekete Mohamed Awole Adem Jimma University In collaboration with the Ethiopia Public Health Training Initiative, The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education January 2003 Funded under USAID Cooperative Agreement No. 663-A-00-00-0358-00. Produced in collaboration with the Ethiopia Public Health Training Initiative, The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education. Important Guidelines for Printing and Photocopying Limited permission is granted free of charge to print or photocopy all pages of this publication for educational, not-for-profit use by health care workers, students or faculty. All copies must retain all author credits and copyright notices included in the original document. Under no circumstances is it permissible to sell or distribute on a commercial basis, or to claim authorship of, copies of material reproduced from this publication. ©2003 by Girma Mekete and Mohamed Awole Adem All rights reserved. Except as expressly provided above, no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission of the author or authors. This material is intended for educational use only by practicing health care workers or students and faculty in a health care field. Parasitology 1 Preface The problem faced today in the learning and teaching of Parasitology for laboratory technicians in universities, colleges, health institutions, training health centers and hospitals emanates primarily from the unavailability of textbooks that focus on the needs of Ethiopian students. This lecture note has been prepared with the primary aim of alleviating the problems encountered in the teaching of Medical Parasitology course and in minimizing discrepancies prevailing among the different teaching and training health institutions. It can also be used in teaching any introductory course on medical parasitology and as a reference material. This lecture note is devoted to providing general aspects of parasitology in addition to covering human parasites in two major groups -the protozoa and helminths- including their distribution, habitat, morphology, life cycle, pathogenicity, prevention and control, laboratory diagnosis and their relevance to Ethiopia. It has also appendices, which discuss the collection of laboratory specimens, preservatives of stool sample, frequently used parasitological diagnostic methods and reagent preparation. Finally, it contains a glossary, which summarizes important terminologies used in the text. Each chapter begins by specific learning objectives and after each objective and after each class of parasites review questions are also included. No systemic study has been conducted on the prevalence of human parasites in different ecological zones of Ethiopia but past surveys indicate the presence of all parasites except some that are found in the Far East, South East Asian and Latin American countries and which require specific intermediate hosts. This lecture note tries as far as possible to summarize local literatures that deal with parasite prevalence Parasitology 2 in Ethiopia so that it may address itself particularly to the needs of Ethiopian students. We welcoming the reviewers and users input regarding this edition so that future editions will be better. Parasitology 3 Acknowledgments We would like to acknowledge The Carter Center for its initiative, financial, material and logistic supports for the preparation of this teaching material. We are indebted to The Jimma University and other institutions that support directly or indirectly for the visibility of this lecture note preparation. Our deepest gratitude to Professor Dennis Carlson with out whom these lectures note preparation is not visible. We greatly thank him for his attitude, knowledge, and practice and above all his commitment, concern and dedication toward solving the health problem of Ethiopia. We extend our appreciation to the reviewers and teaching staffs in the different institution for their unreserved contribution for the materialization of this lecture note preparation. Parasitology 4 Contents I. Preface i II. Acknowledgement ii III. Overview iii III. General objectives v CHAPTER ONE - INTRODUCTION 1 1.1 Definition of terms used in parasitology 1 1.2 Sources of exposure to parasitic infections 5 1.3 Mode of transmission 6 1.3.1 Direct mode of transmission 6 1.3.2 Indirect mode of transmission 7 1.4 Route of transmission 7 1.5 Host parasite relationship 8 1.5.1 Effects of parasites on there hosts 8 1.5.2 Host susceptibility factors 8 1.5.3 Escape mechanism of the parasite from the immune system 1.6 General life cycle of parasites 9 1.6.1 Direct life cycle 9 1.6.2 Indirect life cycle 9 1.7 Types of specimen used for parasitological examination 9 1.8 Classification of Parasites 10 1.9 Major differences between parasitic Parasitology 5 protozoa and metazoa 11 CHAPTER TWO - MEDICAL PROTOZOOLOGY 13 2.1 Class- Rhizopoda ( Amoebae) 2.1.1Free living amoeba 11 2.1.2 Free living pathogenic amoebae 28 2.2 Class - Zoomastigophora ( Flagellates) 32 2.2.1 The Oro-intestinal and Urogenital flagellates 32 2.2.2 The Haemo-Somatic Flagellates 45 2.3. Class -Telosporidia 63 2.3.1 Intestinal and tissue Coccidian Parasite 64 2.3.2 Haemosporidia 72 2.4 Class -Ciliatea ( Ciliates) 87 CHAPTER THREE -MEDICAL HELMINTHOLOGY 91 3.1 Platyhelminths 92 3.1.1 Class cestoda (tapeworm) 92 3.1.2 Class trematodes(flukes) 3.1.2.1 Blood Flukes (Schistosmes) 115 3.1.2.2 Liver Flukes 131 3.2.2.3 Intestinal Flukes 139 3.2.2.4Lung Flukes 142 3.2. Nemathelminths 145 3.3.1. Class Nematoda 145 3.3.1.1Intestinal nematodes 145 Parasitology 6 3.3.1.2. Tissue nematodes 168 Appendix I - Laboratory Examination of Specimens 191 A. Stool 193 B. Urine 206 C. Vaginal and urethral discharge 208 D. Blood 209 E. Skin 216 F. The Gram scotch 217 Appendix II - Preservatives of specimens 219 Glossary 228 Bibliography 241 Parasitology 7 Overview The earliest book devoted to Parasitology was published in 1684 by Redi, who provided descriptions of reproductive organs and eggs of Ascaris. In 1817 Lancisi recorded studies of mosquitoes and Vague Surmises about their role in the cause of intermittent fevers. Goldfuss, in 1817, first used the word ‘’protozoa,’’ which was given modern meaning in 1845 by Siebold, Leeuwenhoek (1632-1723) had devised and used simple microscopes, but achromatic objectives in a compound microscope were not used in England until 1824. Gross, in 1849, was the first to describe an amebic parasite in man Entamoeba gingival and Losch identified E. histolytica in 1875. Then came the discovery of mosquito hosts for filariae by Manson (1877 -1878) and Plasmodia by Laveran in 1880, transmission of babesiosis by ticks by Smith and Kilburne in 1894, trypanosomes and their transmission by tsetse flies by Bruce (1895 - 1896), and mosquito transmission of plasmodia by Ross (1897- 1898). After these discoveries, the science of parasitology expanded rapidly. With the aid of microscopes, morphological characters of various parasites were first studied and species and group characteristics were determined. Then several stages of the organisms were related to one another in life-cycle sequence. This provided important information on extrinsic as well as intrinsic development and paved the way for epidemiologic studies. Moreover, the relationship between parasite to host provided a background for studying the pathogenesis of infection in man and reservoir hosts and, indirectly, for understanding clinical aspects. Parasitology 8 Recent investigations have been largely concerned with the ecology of parasitic infections, anatomy and physiology as revealed by electron microscopy, metabolism of the parasite in its host, immunologic phenomena, and the rationale of chemotherapy. Meanwhile, practical methods are being developed to control these infections and to reduce human exposure to them. A landmark of great significance was the publication in 1978 of a two- volume work by B.H. Kean, K.E. Mott and A.J. Russell, which brought together in English translation as the articles on the major discoveries and earliest descriptions by workers in tropical medicine and parasitology. Having set the historical background; now we will see the importance and the scope of Parasitology. Parasitology is a science that deals with an organism that lives in or on another organism in order to have shelter and /or nutrition. Medical parasitology study parasites that is capable of causing disease in humans. In the context of this ecture note, the term parasite refers to organisms, which belong to protozoa (i.e., Rhizopoda, flagellets ciliates, sporozoans, coccidians and Microsporidian) Helminths (Nematodes, Cestodes and Trematodes). Human welfare has suffered greatly because of parasites. A lot of economic loss occurs as a result of infection of domestic animals by parasite, which causes diseases such as fascioliasis and trypanosomiasis. The study of parasitology has more importance to developing countries where the social and economic conditions require great deal of improvement in terms of better clothing, shelter, food, provisions of wells Parasitology 9 and latrines and sewages and other waste disposal facilities together with the means of controlling vectors. Most of the developing countries lie within