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INTESTINAL AND URINARY SCHISTOSOMIASIS DYNAMICS IN SUB- SAHARAN AFRICA Anouk N Gouvras Department of Infectious Disease Epidemiology, Imperial College, London Supervisors Professor Joanne P. Webster Department of Infectious Disease Epidemiology, Imperial College, London Professor Alan Fenwick Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College, London Thesis submitted for the degree of Doctor of Philosophy of Imperial College London, 2010 1 To my mother, Laura Gouvras, for her αρετή, To George Gouvras, for giving me an Ιθακι, And to Tino and Hugo, for keeping me sane by driving me mad. 2 ACKNOWLEDGMENTS I am forever grateful to my supervisor Prof. Joanne P. Webster for giving me this opportunity to develop my research skills, for sending me to Niger, Kenya, Cameroon and Tanzania, all experiences that I cherish, for her support, her insights and discussions and for being so patient with me, I could not have hoped for a better supervisor. And thanks for the G&Ts too. I would like to thank Prof. Alan Fenwick, for his advice, for his generous contributions and for sending me on an adventure in Ethiopia, without a doubt my favourite trip thus far. My particular thanks go to the Dr Amadou Garba, Dr Marie Lamine, and Dr Curtis Kariuki for the work we did in Niger and Kenya, none of this could have been done without their expertise and dedication. I also owe thanks to Dr Marie Lamine for treating me when I was suffering from malaria. And thanks go to her family for taking such good care of me in Niger. None of this work could have been done without the capable and hardworking technicians in Niger and Kenya, especially as they added the fun to field work. Thus I would like to extend my warmest thanks to the field teams of RISEAL, Niger and the National Museums of Kenya. For the laboratory and analysis work I owe special thanks to Dr Alice Norton who trained me, Dr Charlotte Gower for her invaluable advice, Dr Artemis Koukounari for her help with the scary stats, Dr Bonnie Webster, Dr David Rollinson, Dr Russell Stothard and the whole team at the Natural History Museum for the numerous adult worm donations and general advice and discussion. I wish to thank SCI and CONTRAST for the opportunities they provided and for the funding of this research. These past few years would not have been half as enjoyable were it not for the lovely group of friends I made at DIDE, some who have stayed, some who have left. In particular I’d like to thank Poppy, Isobel, Emma, Artemis, James, Andrea, Dan, Thibaut and everybody at DIDE for their support and friendship and for making this department such a great place to work. 3 Special thanks also go to Hafiza Bibi and Anna Wilhelme for being such great admin ladies and for their general wonderfulness. I would also like to thank my wonderfully supportive family and friends Eleanna, Ilektra, Marianna, Stefanos, Laura, Fiona, Leila, Hannah, Emily, Maike, Sarah, Nikki and of course the lovely Rosy Posy. Particular thanks go to Jane Deal and Nathan, Shelagh, Patrick, Luke and Josh Long. Finally, I wish to thank my grandmother Sylvana for the much needed breaks and discussions, my brothers Tino and Hugo for their support and for their wonderful, light-hearted approach to life and most of all, my mother for, well, everything and more. 4 DECLARATION OF ORIGINALITY The work presented in this thesis was carried out within the larger research projects involving Professor Joanne Webster’s research group at Imperial College London and various other institutes. The studies in chapter 2 and 4 was carried out in Kenya with the National Museums of Kenya and involved collaborations with Dr Curtis Kariuki and Dr Charles Lange and was jointly funded by CONTRAST, multidisciplinary alliance to optimize schistosomiasis control and transmission in sub- Saharan Africa, and by the Schistosomiasis Control Initiative. The majority of the prevalence, infection intensity and morbidity data collections were undertaken by the field teams of the National Museums of Kenya, with the exception of the collection of urinary albumin measurements and all parasite genetic material which was carried out by the candidate, with the assistance of Dr Alice Norton in the baseline survey. Statistical analysis of morbidity data was performed by the candidate alongside Dr Artemis Koukounari. The candidate conducted the optimization of the Whole Genome Amplification, with assistance from Dr Charlotte Gower, and performed all genotyping of parasite samples. The candidate conducted all population analysis in chapter 4. The study in chapter 3 was carried out as part of an epidemiological study involved in the research projects of CONTRAST, multidisciplinary alliance to optimize schistosomiasis control and transmission in sub-Saharan Africa which involved collaborations with Dr Amadou Garba of RISEAL, Niger. The prevalence, infection intensity and part of the parasite genetic material was undertaken by the field teams of RISEAL, led by Dr Marie Lamine. However the majority of the parasite genetic material was collected by the candidate. All the parasite genotyping and subsequent population genetic analyses were performed by the candidate. All the data and written work presented in this thesis is the original work of the candidate, conducted under the supervision of Professor Joanne P. Webster and Professor Alan Fenwick at Imperial College London, and all other work has been properly referenced. 5 ABSTRACT Schistosomiasis is a chronic infection by a digean trematode of the genus Schistosoma. More than 207 million people are infected with this parasite, of which 120 million are symptomatic. There are two main species infecting humans in sub-Saharan Africa: Schistosoma haematobium and S. mansoni, both occur in areas with similar socio-economic and environmental conditions and often have matching distribution patterns. The principle aims of the research presented in this thesis were to further our understanding of schistosome population genetics, associated human host morbidity and chemotherapeutic treatment of schistosomes in relation to mixed species infections. Structured sampling of parasites and/or host traits from school-aged children at baseline and post Mass Drug Administration (MDA) in Niger and Kenya were performed. The results presented provided evidence for S. haematobium - S. mansoni interactions and their impact on the human host and on the parasite population. In Kenya coinfections had lower S. haematobium related morbidity relative to single S. haematobium infections pre and post MDA. Additionally parasite infra-populations from coinfected children had higher genetic diversity levels compared to single infected children in mixed infection foci. In Niger, an impact of MDA on the population genetics of S. mansoni was detected in one mixed infection village, characterised as a noticeable bottleneck effect, but not in the other. There was no aapparent impact of MDA on the population genetics of S. haematobium. Conversely, in Kenya, a significant impact of MDA on both species was detected, with a bottleneck effect occurring on the S. haematobium population and conversely, an increase in genetic diversity in the S. mansoni population. The results of this thesis are discussed in terms of their implications on schistosome epidemiology and evolution, and in relation to the control of schistosomiasis in sub-Saharan Africa 6 TABLE OF CONTENTS INTESTINAL AND URINARY SCHISTOSOMIASIS DYNAMICS IN SUB-SAHARAN AFRICA ...................................... 1 ACKNOWLEDGMENTS ............................................................................................................................................... 3 DECLARATION OF ORIGINALITY .................................................................................................................................... 5 ABSTRACT .............................................................................................................................................................. 6 TABLE OF CONTENTS ................................................................................................................................................ 7 GLOSSARY ............................................................................................................................................................ 13 GENERAL INTRODUCTION ........................................................................................................................................ 15 Schistosomiasis............................................................................................................................................. 15 Schistosoma species ..................................................................................................................................... 15 Life Cycle of African Human Schistosoma..................................................................................................... 15 Human Pathology of Schistosomiasis........................................................................................................... 16 Schistosoma Control, Genetics and Evolution .............................................................................................. 17 Polyparasitism .............................................................................................................................................. 20 Thesis Aims and Structure ...........................................................................................................................