European Commission DG Environment Literature study on the impact of biodiversity changes on human health Contract number: 07-0307/2009/533527/ETU/B3 Final report July 5, 2010 Final report Authors: Daniela Zaghi, Comunità Ambiente Srl Barbara Calaciura, Comunità Ambiente Srl Oliviero Spinelli, Comunità Ambiente Srl Marcello Basili, Siena University Roberto Romi, Istituto Superiore di Sanità Contact Comunità Ambiente Srl Oliviero Spinelli – Daniela Zaghi +39 06 5806070 [email protected] www.comunitambiente.eu Suggested citation of this report: Zaghi D., Calaciura B., Basili M., Romi R. and Spinelli O. (2010). Literature study on the impact of biodiversity changes on human health. Comunità Ambiente Srl, report for the European Commission (Directorate General Environment), July 2010. Disclaimer: This report contains the results of research by the authors and is not to be perceived as the opinion of the European Commission. The authors does not accept any liability for any direct or indirect damage resulting from the use of this report or its content. Literature study on the impact of biodiversity changes on human health Final report CONTENTS Executive summary 1 Human infectious diseases 1 Medicines 3 Chapter 1 Introduction 4 1.1 Purpose of this review 4 1.2 Biodiversity and ecosystem services 6 1.3 The importance of biodiversity and ecosystem services for human health 8 Chapter 2 Biodiversity, ecosystem changes and human infectious diseases 9 2.1 Changes in biodiversity, ecosystems and human infectious diseases 9 2.1.1 Changes in species diversity 11 Pathogens 11 Vectors 12 Hosts 12 Preys and predators 15 Allochthonous species 15 2.1.2 Changes in habitat structural diversity 17 Deforestation and reforestation 17 Modifications of aquatic ecosystems 18 Changes in agro-ecosystems 19 Urbanization 20 Soil alteration 21 2.2 The human infectious diseases relevant in the analysis of the impact of changes in biodiversity and ecosystems changes 22 2.2.1 Malaria 24 2.2.2 Mosquito-borne arbovirosis 29 Yellow fever 32 Dengue 34 Chikungunya fever 35 West Nile fever 36 2.2.3 Leishmaniasis 41 2.2.4 Tick-borne diseases 46 Lyme disease 47 Tick-borne encephalitis 50 2.2.5 Avian influenza 52 Literature study on the impact of biodiversity changes on human health Final report Chapter 3 The socio-economic impacts of the changes in incidence of infectious diseases 57 3.1 The global disease burden 57 3.2 Health, income and economic growth 57 3.2.1 Health and growth 58 3.2.2 Two different approaches 61 3.3 Economic impacts of infectious diseases relevant in the analysis of the impact of changes in biodiversity 63 3.3.1 Different approaches in evaluating the burden of diseases 63 3.3.2 Malaria 67 3.3.3 Yellow fever 74 3.3.4 Dengue 77 3.3.5 Chikungunya fever 80 3.3.6 West Nile fever 82 3.3.7 Leishmaniasis 83 3.3.8 Lyme disease 86 3.3.9 Tick-borne encephalitis 88 3.3.10 Avian influenza 89 Chapter 4 Medicines from biodiversity 92 4.1 Traditional medicines 92 4.2 Modern medicines 93 4.3 The dependence of traditional and modern medicines on biodiversity 95 4.3.1 The use of natural products in traditional medicine 97 4.3.2 The use of natural products in modern medicine 98 Terrestrial sources 98 Marine sources 99 Natural compounds in the pharmaceutical industry 99 4.4 The potential importance of undiscovered species for medicines 101 4.4.1 Prospecting biodiversity for new drugs 103 4.5 The existing and future value of medicines derived from nature 104 4.5.1 Value of nature for commercial drugs 106 4.5.2 Value of biodiversity for traditional medicine 109 Conclusions 110 Human infectious diseases 110 Medicines 112 Abbreviations and acronyms 113 Literature study on the impact of biodiversity changes on human health Final report Appendix: Tables with costs of the relevant infectious diseases using different measures 115 References 122 Literature study on the impact of biodiversity changes on human health Final report Literature study on the impact of biodiversity changes on human health Final report page 1 EXECUTIVE SUMMARY Maintaining biodiversity underpins the stability of ecosystems and the services that they supply to the community, such as food, drinking water, clean air, control of disease and raw materials for the development of medicinal drugs. These are essential to human health. The objective of this literature study is to provide an overview of existing information concerning the impacts of changes in biodiversity and ecosystems on two services related to human health: regulation of infectious diseases and provision of medicines. Human infectious diseases The review focuses on infectious diseases in the human population, in particular vector- borne diseases (VBD), because, as pointed out in the Millennium Ecosystem Assessment: • these diseases are highly sensitive to changes in the natural environment, i.e. environmental conditions affect both the infectious pathogens and the insects and other intermediate hosts that transmit them; • many such infections are related to specific ecosystems (such as forests and wetlands); • VBDs are major killers, causing approximately 1.4 million deaths per year worldwide. Due to the increasing impact of biodiversity changes they are expected to represent the largest share of the future disease burden. The VBDs included in the review were selected on the following criteria: • the direct impact of biodiversity and changes in ecosystems on their spread; • their current high frequency and incidence on human health (VBDs affect over 700 million people every year worldwide); • the occurrence of outbreaks outside their traditional areas (the so-called emerging diseases) and reappearance in areas where these diseases were considered eradicated or contained (the so-called re-emerging diseases). The diversity of species of intact ecosystems can protect mankind against the emergence and spread of infectious diseases. Disease transmission cycles are generally kept in equilibrium by population limiting processes (such as acquired immunity to infectious disease, predation and competition for food) and by the carrying capacity limits of habitats for hosts and vectors. In stable ecosystems each species occupies a particular position or niche and in so doing impedes the invasion of “foreign” species which may form part of an infectious disease cycle, either as predators, prey, hosts, vectors or parasites. There is increasing evidence that greater species richness may decrease the spread of pathogens to humans. Species rich communities are more likely to be populated by highly competitive species which leave fewer vacant niches for possible invasion by species carrying infectious agents. Recent data indicate that higher host diversity (synonymous with species richness) may decrease the risk of disease through a “dilution effect”, i.e. a reduced likelihood that “vectors” (organisms which carry pathogens) come in contact with pathogen hosts. However, although a greater diversity of hosts can reduce transmission rates of particular diseases, they may also harbour additional pathogens. The relative role of species richness Literature study on the impact of biodiversity changes on human health Final report page 2 versus species composition remains to be clarified, as changes in the level of biodiversity affect not the number of species but also their composition. Alteration of natural ecosystems through human activity influences the distribution and incidence of vector-borne infectious diseases. Alterations to ecosystem are diverse and often interrelated. They include introduction of alien species; loss, fragmentation and deterioration of habitats; changes in the distribution and availability of surface water; changes in agricultural practice, urbanisation and other changes in land use. Ecological alterations directly or indirectly affecting the populations of the pathogen, the vector, or the nonhuman hosts of the pathogen and the context within which they interact, may disrupt their complex relationships, destabilise natural equilibrium and alter the epidemiology of vector-borne diseases. Conditions for disease transmission may be enhanced or transmission cycles disrupted. Links between biodiversity change and infectious diseases of humans occur at all levels of biology, from genetics of individual organisms to the structural diversity of habitats. Any disturbance in an ecosystem can induce: • genetic changes in disease pathogens (e.g. change in pathogen virulence), • changes in population dynamics of vectors or hosts species (abundance, diversity, composition, distribution), changes in the community (predation, competition, population density, etc.), • changes in structural diversity (structure, complexity of habitats, size, fragmentation and distribution, area- species relationships). Changes to an environment brought about by human activity can drive selection processes of vectors and pathogens leading to the expansion of those vector and strains suited to the new environmental conditions. An example of newly evolved pathogens include newly re- assorted influenza strains. The potential for mutability allows pathogens to switch hosts migrating into a new ecological niche. This ‘‘host transfer” is easier at the interface between wild communities and agricultural communities with high population densities of humans, domestic animals, and crops, where higher is the vector-host contact rate. Some human infectious diseases are linked to population dynamics of vectors, hosts and pathogens, e.g. high risk or incidence of Lyme