Climate Changes and Emerging Wildlife-Borne Viruses in Norway: Facts, Uncertainty and Precaution Biosafety Report 2014/01 Biosafety Report 2014/01 GenØk - Centre for Biosafety, Tromsø, Norway February 2014 Climate Changes and Emerging Wildlife-Borne Viruses in Norway: Facts, Uncertainty and Precaution Terje Traavik, Dr. philos. 1GenØk-Centre for Biosafety, Norway 2Institute of Pharmacy, UiT - The Arctic University of Norway “The words of Dr. Gro Harlem Brundtland, former director of the World Health Organization (WHO), were indeed prophetic. In her speech at the United Nations Global Leadership Awards on April 19, 2001, she stated that in a modern world, bacteria and viruses travel almost as fast as money. With globalization, a single microbial sea washes over all humankind and there are no health sanctions. In actuality, that sea washes not over just all humankind, but also across all animal and environmental domains” (AMVA 2008). GenØk - Centre for Biosafety, Forskningsparken i Breivika, Postboks 6418, 9294 Tromsø, Norway Tel.: (+47) 77 64 66 20 - [email protected] – www.genok.com Cover photo credits: Andrew Howe/Andrew Howe/RolfAasa (all istockphoto.com)/J. Gathany (Center for Disease Control) 1 I. Preface Globally spoken, some of the most burdening diseases of wildlife animals, livestock and human populations are caused by viruses with hosts and reservoirs in wildlife vertebrates like small rodents and bats. Many of these viruses are transmitted within and between vertebrate species by blood- sucking invertebrates such as mosquitoes, ticks and midges. Until now, the occurrence and distribution of such viruses have, in a relative sense, been restricted to areas within the tropical, subtropical and temperate lower latitude regions of the planet. Through its impacts on competent virus hosts, reservoirs and vectors climate is a decisively important determinant for the distribution of a given virus. Suboptimal temperature is probably the most important single barrier to northwards spread of viruses that may have substantial influence on ecosystem as well as society health and resilience. Through the ongoing global warming, and a diverse set of climate changes, the ecosystems and societies of northern Europe will most certainly be confronted with invading, potentially harmful, vertebrate- and invertebrate-vectored viruses. The human, livestock and wildlife populations in our part of the world will have no former evolutionary experience with, and may lack immunological protection against, the invading viruses. The scenarios and prospects that are presented in this report call for risk assessment, governance and prevention according to a precautionary strategy. The approaches must be based on increased epi- disciplinary research efforts, including participants from all relevant scientific fields within the biological, medical and veterinary areas. Furthermore, the hosts, vectors and viruses do not respect any national or political borders. Accordingly, international cooperation within research, surveillance and monitoring will be totally essential for protection of biological diversity as well as ecosystem, animal and human health. There are huge knowledge gaps with regard to the effects of climate changes on local, regional and global virus-host-vector interactions and adaptations. This report was made possible by a commission from the Norwegian Environment Agency (formerly the Directorate for Nature Management). It took substantially more time than stipulated to finalize the report, and I wish to thank our coworkers in the Agency for their support as well as their patience. I am grateful to my close friend and colleague Reidar Mehl for photos and valuable inputs. Likewise, my friend and colleague Thomas Bøhn has delivered substantial inputs and support. Finally, I gratefully acknowledge the contributions of Anne Myhr and Katrine Jaklin, which have resulted in the attractive design of the final report. 2 Contents I. Preface ........................................................................................................................................................ 2 II. Abstract ...................................................................................................................................................... 8 III. Executive Summary .............................................................................................................................. 11 1. General Introduction ........................................................................................................................... 15 1.1. Purpose and goals ............................................................................................................................................ 15 1.2. Climate change and wildlife infectious agents ..................................................................................... 15 1.3. Transmission and impacts of viruses with wildlife reservoirs and hosts ................................ 17 1.3.1. Transmission ................................................................................................................................................ 17 1.3.2. Hosts ................................................................................................................................................................ 18 1.3.3. Beneficial viruses? ...................................................................................................................................... 18 1.3.4. Reservoirs ...................................................................................................................................................... 18 1.3.5. Co-infections with different vector-borne viruses ....................................................................... 19 1.3.6. Do we know the viruses already circulating in Norway? ........................................................... 20 1.3.7. Conclusion ..................................................................................................................................................... 20 1.3.8. General questions ....................................................................................................................................... 20 2. Viruses are not microorganisms or cells, they are viruses! .................................................. 22 3. Lifecycles of vector-borne viruses: participants and complexity........................................ 25 3.1. The ecological episystem .............................................................................................................................. 25 3.1.1. Virulence ........................................................................................................................................................ 26 3.1.2. Interactions between viruses circulating within the same episystems? ............................. 26 3.2. Arthropod vectors ........................................................................................................................................... 26 3.2.1. Mosquitoes .................................................................................................................................................... 26 3.2.2. Ticks ................................................................................................................................................................. 27 3 3.2.3. Midges ............................................................................................................................................................. 30 3.2.4. Transovarial, transstadial and venereal virus transmission .................................................... 30 3.2.5. Climate change impacts on arthropods ............................................................................................. 30 3.3. Vertebrate vectors and hosts ...................................................................................................................... 31 3.3.1. Birds ................................................................................................................................................................. 31 3.3.2. Mammals ........................................................................................................................................................ 32 3.3.3. Reptiles and amphibians ......................................................................................................................... 33 3.4. Direct and indirect impacts of climate change on vector-borne viruses: relevant variables and effect parameters .................................................................................................................................................... 33 4. Arboviruses ............................................................................................................................................. 35 4.1. Definitions ........................................................................................................................................................... 35 4.2. Nomenclature and taxonomy...................................................................................................................... 35 4.3. Lack of reliable disease and distribution data ..................................................................................... 35 4.4. Natural life history and ecology ................................................................................................................