Taenia Solium Transmission in a Rural Community in ·Honduras: an Examination of Risk Factors and Knowledge
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Taenia solium Transmission in a Rural Community in ·Honduras: An Examination of Risk Factors and Knowledge by Haiyan Pang Faculty of Applied Health Sciences Brock University A thesis submitted for completion of the Master of Science Degree Haiyan Pang © 2004 lAMES A GIBSON LIBRARY . BROCK UNIVERSITY sr. CAtHARINES· ON Abstract Taenia soliurn taeniasis and cysticercosis are recognized as a major public health problem in Latin America. T. soliurn transmission not only affects the health of the individual, but also social and economic development, perpetuating the cycle of poverty. To determine prevalence rates, population knowledge and risk factors associated with transmission, anepidemiological study was undertaken in the rural community of Jalaca. Two standardized questionnaires were used to collect epidemiological and T. soli urn general knowledge data. Kato-Katz technique and an immunoblot assay (EITB) were used to determine taeniasis and seroprevalence, respectively. In total, 139 individuals belonging to 56 households participated in the study. Household characteristics were consistent with conditions of poverty of rural Honduras: 21.4% had no toilet or latrines, 19.6% had earthen floor, and 51.8% lacked indoor tap water. Pigs were raised in 46.4% of households, of which 70% allowed their pigs roaming freely. A human seroprevalence rate of 18.7% and a taeniasis prevalence rate of 2.4% were found. Only four persons answered correctly 2: 6 out of ten T. soliurn knowledge questions, for an average passing score of 2.9%. In general, a serious gap exists in knowledge regarding how humans acquire the infections, especially neurocysticercosis was identified. After regression analysis, the ability to recognize adult tapeworms and awareness of the clinical importance of taeniasis, were found to be significant risk factors for T. soliurn seropositivity. These results demonstrate a high level of transmission and a low level of kn~,wledge about Taenia soliurn in Jalaca. Consequently, intervention measures integrated with health education are necessary to decrease the burden caused by this parasite. 11 Acknowledgement I would like to extena my sincere gratitude and appreciation to many people who made this Master's thesis possible: A special word of thanks must go to my supervisor - Dr. Ana L. Sanchez. She was the most indispensable person during my graduate study in Canada. Her patience and continuous help, extremely valuable comments, suggestions, and encouragement helped me at all times during the research and writing of this thesis. It is my great pleasure to conduct this thesis under her supervision. I wish to express my gratitude to the members of my advisory committee - Drs. Susan Arai and Shelley Lothian from the Department of Community Health Sciences, who gave invaluable suggestions to complete this thesis and provided a motivating, enthusiastic, and critical atmosphere during the many meetings we had. Additionally, I also received much help from the Faculty of Applied Health Sciences. Special thanks to: Dr. Michael Plyley, the Assistant Dean for Research and Graduate Studies, for providing tremendous support during my study process; Dr. Philip Sullivan, Assistant Professor of the Department of Physical Education and Kinesiology for his instruction and advice regarding the statistics for my thesis; Dr. Huidi Wang, Associate Professor of the Department of Community Health Sciences for her continued encouragement and for the wonderful job chairing my thesis defence; Beverly Minor, the Faculty's research and graduate coordinator for guiding me through the administrative aspects of the program; and finally, to everybody from the Faculty of ~, ",', Applied Health Sciences and Graduate office for participating in various ways to help and ensure the accomplishment of my research. I am sincerely thankful to them all. iii Needless to say, I could not have survived these two years and smoothly accomplished my Master's program in Canada without the support of my friends, family and relatives, whom I want to thank: My friends, Lili Ding, Tony Chen, Jiajie Dong, and Xiaowei Wang in Canada, and Li Gao, Jieying Wu, Jian Wang, Xiaoping Yin, and Echo Cheung (Taiwan) in China, who offered me their warm friendship, acceptance and support that helped me get through difficult times as well as greatly enjoy the good ones. My father, the foremost person I want to express my appreciation to. He carries the dual burden and responsibilities of being a father and a mother to me, after my natural mother~s death in 1997. He provides me with duplicate attention and love. Without his firm encouragement, determination and support, I could not have come to Canada to continue my graduate studies. I do and will always dedicate my life to return what my father has given to me. My step-mother and brother are the most special persons in my life. They give me a warm integrity family. Without them, I could not have easily survive and adapt to the life in Canada. Their benevolence is also unforgettable during my whole life. I am also very grateful to all my relatives in China, who from the distance have given me tremendous emotional support. Meanwhile, I am particularly indebted to my grandrnother (from my natural mother's side) and grandfather (from my father's side), who left me during the period I was in Canada. They will live in my heart forever. The most profound thanks go to my natural mother. As my mother, sister, friend \ an<lteacher, she occupies the most important place in my heart. She is the person leading V, my professional aspirations in the health and medicine domain. She is and forever will be the most cherished person in my life. Susan Arai t~±~ Shelley Lothian t~± - *ji;jJtX1M!.1fJEfllMt!&':o M!.1fJ~-=f7!!t }liS(; Huidi Wang tw:±, 1'FJg Community Health Sciences *mIJ~~, ~7!!t¥-¥~ \ EflMJhJJ, illJ@iMM!.JiJ(;:9JEfl:±¥-¥ 7!!tEfl~±itJt~~; Beverly Minor j(±, M!.1'FJg~ ~., ~Eflf41iJf ~1iJf~~I 1'F1~}iJjff!, 1:E1TJJ&1Jrni~-=f 7!!t1~$Eflt~§I; :lIJq, JJi~~iM m:ff@m1tm~~~1iJf~~1}0:¥:EflI 1'FAff!, 1£ 1t!YM!.1fJ$ 1JrniEflfflWiF , 1t~!!t v R~reR.~m~~W*~R~~~~~o~~-~~~,~m,~M~,x ~~~*~~~~A,f')· R~~~~~~a~~~~ ••m~~~~o~~~, a~ vi Table of Contents Page List of Tables....... .. ..... .... ... ... ....... ......... ..... ... .............. ...................... xv List of Figures. .. ..... xviii List of Appendices... .. ... xix List of Abbreviations........................... ........................ ............... ......... xx Glossary of Parasitology Tenus... ............ .... ........... ............ ......... ...... ...... xxii Chapter One - Introduction.. .. .... .. ..... ... .. .. .. ... ... 1 Chapter Two - Review of Literature....................................................... 6 History... .......... ........ ......... ........ ...................... ... ............... ........... 6 Taxonomy.................................................................................... 7 Morphology. .. .. .. .. .. .. .. .. .. .. .. 8 Life Cycle. .... .. .. .. ... .. ..... .. .. ... .. .. ... ... .... .. ... 10 Epidemiology.............................................................................. 12 Global Distribution.......................................... .................. ...... 12 Prevalence of Taenia solium in the Americas............................... 13 Prevalence of Taeniasis...... .................. ..................... ...... 14 Seroprevalence of Human Anti-Taenia solium Antibodies and Associated Epilepsy....................................................... 15 Seroprevalence of Human Anti-Taenia soliutn Antibodies..... 15 Seropositivity for Taenia solium and Associated Epilepsy..... 18 Seroprevalence of Anti-Taenia solium Antibodies and Prevalence of Cysticercosis in Swine.................. ........ .... 19 Prevalence of Taenia solium Outside of the Americas......... ............ 20 vii Prevalence of Taeniasis................................................... 20 Seroprevalence of Human Anti-Taenia solium Antibodies and Associated Epilepsy. 22 Seroprevalence of Human Anti-Taenia solium Antibodies..... 22 Seropositivity for Taenia solium and Associated Epilepsy.. ... 22 Seroprevalence of Porcine Anti-Taenia solium Antibodies and Prevalence of Porcine Cysticercosis. 24 Risk Factors ........... :............................................................ ... 26 Risk Factors Associated with Taeniasis... ....... ..... ... ... ......... ... ..... 26 Risk Factors Associated with Human Cysticercosis..................... ... 27 Pathology, Immunology, Clinical Presentation, Diagnosis and Treatment of Taeniasis and Cysticercosis ........... ;.................................................. 31 Taeniasis. ... 31 Pathology and Immunology of Taeniasis...... ...... ...... .................. 31 Clinical Presentation of Taeniasis.......................................... ... 31 Diagnosis of Taeniasis......................................................... 31 Parasitologic Diagnosis...... ........................ ... .................. 32 Immunological and Molecular Diagnoses........................... ... 32 Treatment of Taeniasis... ... ........................ ....................... .... 33 Cysticercosis.......... .... ....... ... ... ......... ..... ................ .............. ... 34 Human NetIrocysticercosis ........................................................ 35 Pathology and Immunology ofNeurocysticercosis ....................... 35 Clinical Presentations ofNeurocysticercosis............ ............... ..... 37 viii Diagnosis of Neufocysticercosis.............................................