Doctoral thesis University of Limoges Gay Lussac Doctoral School - Science for the Environment (ED 523) École Doctorale Gay Lussac - Sciences pour l’Environnement (ED 523) INSERM UMR 1094 Laboratory of Parasitology Thesis to obtain the grade of Doctor of University of Limoges Discipline/Speciality: Parasitology Presented and supported by Patcharee CHAICHAN 25 April 2017 Epidemiology of Toxoplasma gondii in Thailand Thesis directed by Pr. Marie-Laure DARDÉ, Pr. Yaowalark SUKTHANA, Dr. Aurélien MERCIER and Dr. Aongart MAHITTIKORN JURY: President of jury Prof. Gilles DREYFUSS, Professor, Laboratory of Parasitology and Mycology, University of Limoges, France Reporters Prof. Marie-Hélène RODIER, Professor, Laboratory of Parasitology and Mycology, University of Poitiers, France Dr. HDR, Dominique AUBERT, Lecturer, Laboratory of Parasitology and Mycology, University of Reims Champagne-Ardenne, France Examiners Prof. Gilles DREYFUSS, Professor, Laboratory of Parasitology and Mycology, University of Limoges, France Prof. Marie-Laure DARDÉ, Professor, Laboratory of Parasitology and Mycology, University of Limoges, France Prof. Yaowalark SUKTHANA, Professor, Department of Protozoology, University of Mahidol, Thailand Dr. Aurélien MERCIER, Lecturer, Laboratory of Parasitology, University of Limoges, France “Never compare yourself or others to other people. Everyone has their own struggles, own fights, and a different path that they choose to get to where they are. Everyone is who they are for a reason.” “Never give up on something you really want. However impossible things may seem. There’s always a way.” “Experience tells you what to do; Confidence allows you to do it.” 2 Acknowledgement Firstly, I would like to thank to my principle supervisors, Pr. Marie-Laure Dardé and Pr. Yaowalark Sukthana who kindly accepted me for this project, supervised and mentored my work and gave me many advices to overcome the obstacles for along my thesis. Her advices were really useful and appreciated. I would also thank to my co-advisors, Dr. Aongart Mahittikorn for his kindness and his assistance during my field works and for the periods when I stayed at department of Protozoology, Faculty of Tropical Medicine, Mahidol University. Dr. Aurélien Mercier, for his advices regarding many laboratory experiments. I will never forget, to specially thank to Ministry of Science and Technology, government of Thailand and Thai Embassy in France for the funding of all my academic education: Bachelor, Master and Doctorate's degree in France. I would like specially thank to Pr. Pierre-Marie Preux for his great responsibility to develop our team INSERM UMR 1094. I would like to thank to all the members of the thesis jury: Pr. Gilles Dreyfuss, Pr. Marie- Hélène Rodier and Dr. Dominique Aubert for the time they devoted. My thanks also go to, Dr. Philippe Vignoles for his generosity and his contribution for all statistical analyses. Dr. Farid Boumédiène for his kindness and his participation to create the geographical charts. Dr. Daniel Ajzenberg for the sharing on genetic diversity information. Dr. Kamlang Chumpolbanchorn for his assistance to collect the samples for the field work in Kanchanaburi province. Dr. Bertrand Courtioux for his kindness and his support. I would like also to thank to INSERM UMR 1092 team, especially to Dr. Thomas Jové and Dr. Olivier Barraud who helped me carrying out the identification of bacteria and to resolve the problem of bacterial contamination. I would like to take this opportunity to thank all the people of UMR 1094 team. Specially thank to Martine Gatet, Rozeline Mouzet, Muriel Matias and Homayoun Riahi who helped me realizing the laboratory experiments, provided many materials and reagents to carry out the experiments. Especially for their generosity, kindness and their welcoming smiles. 3 I am very grateful for the help of Nicolas Plault with his kindness, his availability, who helped me a lot especially for the mouse inoculation and genotyping experiments. I would like to thank to Ms. Ruenruetai, Mr. Peerapong, Ms. Rapeepan, Ms. Suparat, Ms. Chantira, Ms. Airada and all the members of department of Protozoology and department of veterinary, Mahidol University. Especially thank to their contribution for the sample collection although very late at night. My thanks also go to all PhD. students and Master students of Laboratory of Parasitology UMR 1094, Emilie, Clotilde, Paula, Julien, Lokman, Marie-Pauline and Azra. Thank to their kindness allow having the good moments between us. Big thanks to Karim, ancient PhD. student who devoted his time showing several laboratory experiments to me. I would like specially thank to my dear friends, Noona Mayoura, Tik Phetvongsinh, Xia, Nafissa, Adama, Wisut, Kritsana, Caroline and Mélissa. Thank you for everything and especially for your sincere encouragements. A very special thanks to my French host family, Annick and Joël. Thank you to help me to learn and progress in French language. I am very happy to know your family. More than 10 years that I am in France, you are considered as my second parents. Finally, sincerely thanks to my beloved family (my parents and my sister) for their encouragements during this long period of thesis, as well as special thanks to my best friend Thanwa for your encouragement in the worst and best moments during this thesis even with a long distance. Many thanks Merci beaucoup 4 Droits d’auteurs Cette création est mise à disposition selon le Contrat : « Attribution-Pas d'Utilisation Commerciale-Pas de modification 3.0 France » disponible en ligne : http://creativecommons.org/licenses/by-nc-nd/3.0/fr/ 5 Table of contents Acknowledgement ................................................................................................................................. 3 List of figures ......................................................................................................................................... 8 List of tables ......................................................................................................................................... 10 Abbreviations ....................................................................................................................................... 12 Introduction ......................................................................................................................................... 13 Chapter I: Generality on Toxoplasma gondii .................................................................................... 15 I. Taxonomy of T. gondii ................................................................................................................... 15 II. Description of the parasite and its stages of development ............................................................ 15 II.1. Tachyzoites ............................................................................................................................ 16 II.2. Bradyzoites ............................................................................................................................ 16 II.3. Oocysts .................................................................................................................................. 17 III. Life cycle of T.gondii .................................................................................................................. 18 III.1. The asexual cycle ................................................................................................................. 18 III.2. The sexual cycle ................................................................................................................... 19 IV. How do humans become infected?.............................................................................................. 20 V. Human toxoplasmosis .................................................................................................................. 20 V.1. Clinical features of toxoplasmosis ......................................................................................... 20 Chapter II: Southeast Asian countries and Toxoplasmosis ............................................................. 23 I. Description of Southeast Asian Region ......................................................................................... 23 II. Climatic characteristics of Southeast Asia .................................................................................... 25 III. Focus on Thailand and overview (our study area) ...................................................................... 26 III.1. Geography ............................................................................................................................ 27 III.2. Climate ................................................................................................................................. 27 III.3. Human population ................................................................................................................ 30 IV. Literature review ......................................................................................................................... 34 IV.1. Seroepidemiology of Toxoplasma infection in Southeast Asian countries .......................... 34 IV.2. Seroprevalence of T. gondii in animals ................................................................................ 35 IV.3. Seroprevalence of T. gondii in humans ................................................................................ 45 V. Clinical