Epidemiology of Angiostrongylus cantonensis and eosinophilic meningitis in the People’s Republic of China INAUGURALDISSERTATION zur Erlangung der Würde eines Doktors der Philosophie vorgelegt der Philosophisch-Naturwissenschaftlichen Fakultät der Universität Basel von Shan Lv aus Xinyang, der Volksrepublik China Basel, 2011 Genehmigt von der Philosophisch-Naturwissenschaftlichen Fakult¨at auf Antrag von Prof. Dr. Jürg Utzinger, Prof. Dr. Peter Deplazes, Prof. Dr. Xiao-Nong Zhou, und Dr. Peter Steinmann Basel, den 21. Juni 2011 Prof. Dr. Martin Spiess Dekan der Philosophisch- Naturwissenschaftlichen Fakultät To my family Table of contents Table of contents Acknowledgements 1 Summary 5 Zusammenfassung 9 Figure index 13 Table index 15 1. Introduction 17 1.1. Life cycle of Angiostrongylus cantonensis 17 1.2. Angiostrongyliasis and eosinophilic meningitis 19 1.2.1. Clinical manifestation 19 1.2.2. Diagnosis 20 1.2.3. Treatment and clinical management 22 1.3. Global distribution and epidemiology 22 1.3.1. The origin 22 1.3.2. Global spread with emphasis on human activities 23 1.3.3. The epidemiology of angiostrongyliasis 26 1.4. Epidemiology of angiostrongyliasis in P.R. China 28 1.4.1. Emerging angiostrongyliasis with particular consideration to outbreaks and exotic snail species 28 1.4.2. Known endemic areas and host species 29 1.4.3. Risk factors associated with culture and socioeconomics 33 1.4.4. Research and control priorities 35 1.5. References 37 2. Goal and objectives 47 2.1. Goal 47 2.2. Objectives 47 I Table of contents 3. Human angiostrongyliasis outbreak in Dali, China 49 3.1. Abstract 50 3.2. Introduction 51 3.3. Materials and methods 52 3.3.1. Ethics statement 52 3.3.2. Retrospective survey and establishment of surveillance system 52 3.3.3. Diagnostic criteria 53 3.3.4. Additional investigations 53 3.3.5. Data analyses 54 3.4. Results 55 3.4.1. Epidemiology 55 3.4.2. Clinical characteristics 56 3.4.3. Treatment 58 3.4.4. Additional investigations 59 3.5. Discussion 59 3.6. Acknowledgement 62 3.7. References 62 4. Invasive snails and an emerging infectious disease: results from the first national survey on Angiostrongylus cantonensis in China 67 4.1. Abstract 68 4.2. Introduction 69 4.3. Methods 70 4.3.1. Ethics statement 70 4.3.2. Design of the national survey on A. cantonensis 70 4.3.3. Field survey of A. cantonensis and its hosts 71 4.3.4. Analysis 71 4.4. Results 72 4.4.1. A. cantonensis hosts and their infection status 72 4.4.2. Geographic distribution of A. cantonensis and its main hosts 74 4.4.3. Intermediate host snails on markets and restaurants 76 II Table of contents 4.4.4. Commercial snail farming 77 4.5. Discussion 77 4.6. Acknowledgement 81 4.7. References 81 5. The complete mitochondrial genome of the rodent intra-arterial nematodes Angiostrongylus cantonensis and A. costaricensis 87 5.1. Abstract 88 5.2. Introduction 89 5.3. Materials and methods 90 5.3.1. Parasites and DNA extraction 90 5.3.2. PCR amplification and sequencing 91 5.3.3. Sequence analyses 91 5.3.4. Phylogenetic analysis 92 5.4. Results and discussion 93 5.4.1. Mitochondrial genome of A. cantonensis and A. costaricensis 93 5.4.2. Comparison with other nematode mt genomes 98 5.4.3. Phylogenetic analysis 101 5.5. Conclusion 102 5.6. Acknowledgement 103 5.7. References 103 6. Genetic diversity of Angiostrongylus cantonensis in its presumptive home range, and potential scenarios for its spread 107 6.1. Abstract 108 6.2. Introduction 109 6.3. Methods 110 6.3.1. A. cantonensis specimen and total DNA preparation 110 6.3.2. PCR and sequencing 111 6.3.3. Network and phylogenetic analysis 111 6.3.4. Mutation analysis 112 6.3.5. Analysis of geographic distribution patterns 113 III Table of contents 6.4. Results 113 6.4.1. Diversity of A. cantonensis and haplotype network 114 6.4.2. Mutation analysis 116 6.4.3. Scenarios for spread of A. cantonensis 118 6.5. Discussion 121 6.6. Acknowledgement 126 6.7. References 126 7. Population genetics of invasive snail Pomacea spp. in the People’s Republic of China: multiple and secondary introductions 131 7.1. Abstract 132 7.2. Introduction 133 7.3. Methods 134 7.3.1. Apple snail specimen and total DNA extraction 135 7.3.2. PCR and sequencing 135 7.3.3. Data source from GenBank 136 7.3.4. Data analysis 136 7.4. Results 137 7.5. Discussion 143 7.6. Acknowledgement 146 7.7. References 146 8. The emergence of angiostrongyliasis in the People’s Republic of China: the interplay of invasive snails, climate change and transmission dynamics 151 8.1. Summary 152 8.2. Introduction 153 8.3. Methods 155 8.3.1. Current distribution of P. canaliculata and A. cantonensis 155 8.3.2. Key transmission factors of A. cantonensis 157 8.3.3. Climate data 162 8.3.4. Modeling and mapping in a GIS platform 163 IV Table of contents 8.4. Results 163 8.4.1. Current distribution of P. canaliculata in P.R. China, including uncertainty 163 8.4.2. Potential change in the distribution of P. canaliculata in the 2020s and 2030s 166 8.4.3. The potential impact of climate change on A. cantonensis transmission 168 8.5. Discussion 171 8.5.1. Emerging infectious diseases driven by invasive species and climate change 172 8.5.2. Transmission dynamics of parasites from a biological and ecological perspective 173 8.5.3. Vulnerable area to climate change 174 8.6. Conclusions and research needs 175 8.7. Acknowledgement 177 8.8. References 177 9. Discussion and conclusions 183 9.1. Discussion 183 9.1.1. Epidemiology of eosinophilic meningitis with particular consideration to outbreaks 184 9.1.2. Angiostrongylus cantonensis in its presumptive home range and global implications 186 9.1.3. Invasive species and emerging infectious diseases 191 9.1.4. Biology-driven model in context of climate change 194 9.2. Conclusions 197 9.3. Research priorities 198 9.4. References 199 Curriculum vitae 207 V Table of contents VI Acknowledgments Acknowledgements This joint work involved many colleagues in Swiss Tropical and Public Health Institute (Swiss TPH) in Basel and the National Institute of Parasitic Disease (NIPD), China CDC in Shanghai. It is a good pleasure to take this chance to express my sincere thanks to all who were involved in the performance of my thesis. First and foremost, my sincerest thanks are addressed to Prof. Jürg Utzinger from Swiss TPH and Prof. Xiao-Nong Zhou from NIPD. Their close collaboration created the opportunity to register as a Ph.D. student in University of Basel and work with my supervisor Prof. Jürg Utzinger. Their enthusiasm and interest in scientific research is quite impressive and influential. I am deeply grateful to Prof. Jurg Utzinger for his strong support and encouragement in my work. His lovely “garage” is permanently open to me and the enlightening discussions with him constantly make the way smooth. Special grateful lines are addressed to Prof. Xiao-Nong Zhou who was my master supervisor and led me the way to scientific research. As a co-supervisor of this thesis, he kindly provided the selfless support to my work in China. I am grateful to Prof. Marcel Tanner (director of Swiss TPH), Prof. Nino Kuenzli (vice director of Swiss TPH) and Prof. Mitchell Weiss (Head of the Department of Public Health and Epidemiology) for welcoming me and creating a stimulating environment for accomplishing my research. Particular thanks to Peter Deplazes from University of Zurich who kindly accepted our invitation as co-referee of this thesis and attended my Ph.D. examination. I could not imagine the thesis without my research team in NIPD. Seven years ago when I saw Angiostrongylus cantonensis for the first time, it was Prof. Yi Zhang and He-Xiang Liu who tought me how to isolate and identify this parasite from snails and rats. They established the life cycle of Angiostrongylus cantonensis in our laboratory, which provides the platform for subsequent basic research. Later Ling Hu joined us. In the national sampling survey they make much effort to collect the specimens, including infecting laboratory animals. More recently Fu-Rong Wei and Dr. Yun-Hai Guo joined us. My particular thanks are addressed to them. 1 Acknowledgments I am especially grateful to Dr. Peter Steinmann from Swiss TPH who witnessed the whole process from the beginning to final stage of my Ph.D. program. Actually, we got to know each other since 2005 when he did his field work in China. In the following years he not only became my closest collaborator in research but also gave much selfless help in my life in Basel. This thesis involved many field works. Many thanks are addressed to Drs. Li-Sha Li, Zhuo-Hui Deng, Zun-Wei Du, Hong-Man Zhang, Xi-Min Hu, Xiao-Jun Zeng, Zheng-Xiang Li, Li-Na Tang, Xin-Jian Luo and their research groups as well as the colleagues in local centers of diseases control and institutes of parasitic diseases. They made much effort to collect the snail and nematode specimen during the first nationwide survey on Angiostrongylus cantonensis. I am indebted to Prof. Carlos Graeff-Teixeira from Laboratório de Parasitologia Molecular do Instituto de Pesquisas Biomédicas da PUCRS, Brazil and Dr. Praphathip Eamsobhana in Faculty of Medicine Siriraj Hospital in Mahidol University, Thailand. They granted me the specimen of Angiostrongylus costaricensis and Thailand isolate of Angiostrongylus cantonensis, which are the most important references in this work.