Strongyloides stercoralis in Australia by Meruyert Beknazarova B EnvHealth M EnvHealth Thesis submitted to Flinders University for the degree of Doctor of Philosophy College of Science and Engineering 19.08.2019 TABLE OF CONTENTS List of Figures ................................................................................................................................ vi List of Tables ................................................................................................................................. vii List of Abbreviations ....................................................................................................................viii Summary ........................................................................................................................................ xi Declaration ....................................................................................................................................xiii Acknowledgements ......................................................................................................................xiv Statement of Co-Authorship ........................................................................................................ xv Publications .................................................................................................................................xvii 1. Introduction ................................................................................................................................ 1 1.1 Strongyloides stercoralis.......................................................................................................... 1 1.1.1 Life cycle ........................................................................................................................... 1 1.1.2 Clinical outcomes and pathology ....................................................................................... 3 1.2 Strongyloidiasis: A disease of socioeconomic disadvantage .................................................... 4 1.2.1 Abstract............................................................................................................................. 5 1.2.2 Introduction ....................................................................................................................... 5 1.2.3 Global prevalence of strongyloidiasis and climate classification ...................................... 14 1.2.4 Countries of strongyloidiasis prevalence and socioeconomic status ................................ 16 1.2.5 Conclusions .................................................................................................................... 20 1.2.6 Acknowledgments ........................................................................................................... 20 1.2.7 Author contributions ........................................................................................................ 20 1.3 Advocating for both environmental and clinical approaches to control human strongyloidiasis21 1.3.1 Abstract........................................................................................................................... 22 1.3.2 Introduction ..................................................................................................................... 22 1.3.3 Anthelminthic drugs ........................................................................................................ 23 1.3.4 Nematicides .................................................................................................................... 27 1.3.5 Conclusions .................................................................................................................... 29 1.3.6 Acknowledgments ........................................................................................................... 29 1.3.7 Author contributions ........................................................................................................ 29 1.4 Strongyloides stercoralis in Australia ..................................................................................... 30 1.5 Strongyloides stercoralis in dogs ........................................................................................... 31 1.6 Genetic aspects of Strongyloides stercoralis ......................................................................... 31 1.7 Hookworms ........................................................................................................................... 32 1.8 One Health and environmental health approaches ................................................................ 32 ii 1.9 Methods ................................................................................................................................ 33 2. Aim and Objectives .................................................................................................................. 34 2.1 Aim ........................................................................................................................................ 34 2.2 Main objectives ...................................................................................................................... 34 2.3 Thesis structure ..................................................................................................................... 35 3. Argument for inclusion of strongyloidiasis in the Australian National Notifiable Disease List – in memory of Emeritus Professor Rick Speare ................................................................ 36 3.1 Abstract ................................................................................................................................. 38 3.2 Introduction............................................................................................................................ 38 3.3 The Australian National Notifiable Disease Surveillance System (NNDSS) ........................... 39 3.4 Criteria for inclusion on the National Notifiable Disease List .................................................. 40 3.5 Prevalence of strongyloidiasis in Australia ............................................................................. 40 3.6 Socioeconomic impact caused by strongyloidiasis................................................................. 45 3.7 Recommendation to make strongyloidiasis a notifiable disease ............................................. 46 3.8 Author contributions ............................................................................................................... 46 3.9 Acknowledgments ................................................................................................................. 47 3.10 Conflicts of interest .............................................................................................................. 47 3.11 Dedication ........................................................................................................................... 47 4. Validation of DESS as a DNA preservation method for the detection of Strongyloides spp. in canine faeces ............................................................................................................................ 48 4.1 Abstract ................................................................................................................................. 50 4.2 Introduction............................................................................................................................ 50 4.3 Materials and methods .......................................................................................................... 51 4.4 Results .................................................................................................................................. 54 4.5 Discussion ............................................................................................................................. 55 4.6 Conclusions ........................................................................................................................... 56 4.7 Acknowledgments ................................................................................................................. 57 4.8 Author contributions ............................................................................................................... 57 4.9 Conflicts of interest ................................................................................................................ 57 5. Strongyloides stercoralis genotypes in humans and dogs in Australia ............................... 57 5.1 Mass drug administration for the prevention human strongyloidiasis should consider concomitant treatment of dogs .................................................................................................... 59 5.2 Detection of classic and cryptic Strongyloides genotypes by deep amplicon sequencing: A preliminary survey of dog and human specimens collected from remote Australian communities 62 5.2.1 Abstract........................................................................................................................... 64 5.2.2 Author summary .............................................................................................................. 64 5.2.3 Introduction ..................................................................................................................... 64 iii 5.2.4 Methods .........................................................................................................................