updated on Jun 05, 2008

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Global alteration of freshwaters and influences on human and environmental well-being
*Robert J. Naiman1 and David Dudgeon2
1) University of Washington, USA, 2) University of Hong Kong, China
This presentation outlines some basic changes being made to the Earth's freshwater (FW) regime, and we discuss these changes in light of human and environmental well-being. We define 'human and environmental well-being' as factors contributing to sustained healthy conditions - disease resistance or avoidance, good nutrition, species-appropriate reproductive success, and species-appropriate demographics. We also consider the impacts of changing environmental conditions, changes that transcend direct alterations of FW.
As we enter the Anthropocene - a new, human-dominated, geological epoch - the FW portion of the Earth's hydrological system is undergoing profound alterations from human activities. Half of all accessible freshwater is now used by humans. Even though most hydrological alterations are designed to benefit human societies many have unintended - and sometimes severe - consequences for human societies and the environment. One billion people now lack access to clean water, ~80% of all illnesses are water-borne, and poor sanitation kills ~5,000 children each day. The ethical imperative to improve this situation involves new water-resource developments, plus initiatives to use water more efficiently and to reduce pollution/contamination. However, environmental gains from pollution amelioration may be offset by increased water use, limiting allocation of water to sustain environmental functions and biodiversity. Overall, the influences of existing and future water regimes on human and environmental well-being are varied and wide-ranging. Consider that currently >1 billion people live in basins that are likely to require some form of river management intervention for climate change alone. Global declines in FW biodiversity, in the nutritional qualities and abundances of FW and riparian products, and in the 'quality' of life for many species require solutions; as do the increases seen in the spatial extent of FW-related diseases and non-native species. The net result is manifest in non-sustainable demographics for many species and long-term systematic declines in the health of numerous plant and animal populations, including many human societies.
Fortunately, scientists and policy makers are now beginning to think of freshwater in terms of a global water system. They are discussing ways by which the 'system' is being altered and identifying the ecological and policy implications of these changes, they are establishing key international programs dedicated to understanding and resolving major social and environmental issues, and they are developing techniques for widespread application (e.g., environmental flow methodologies). Will these be enough in a rapidly changing world?

Keywords: Freshwater, biodiversity, status, global perspectives, environmental health

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Linkages between isolated wetland ecology and disease ecology in the southern U.S.
*Katherine Kirkman, Lora Smith, Steve Golladay and Steve Opsahl
Joseph W. Jones Ecological Research Center, USA
Small, isolated wetlands are of global significance because of their abundance in many regions and their disproportional contribution to regional biodiversity. However, the relationship between ecologically diverse wetland ecosystems and human health is poorly understood. Because of their small size, periodic dry down, and lack of legal protection in many regions, isolated wetlands worldwide have been drastically reduced or degraded. The connectivity between uplands and wetlands are a key ecological linkage to the support of a healthy ecosystem and regional biodiversity in the fire-maintained habitats of the southeastern coastal plain of the US. Thus, such wetlands are ideal model systems to examine linkages between environmental change, complex food webs, and ecology of mosquito-borne disease. In a long term study, we have examined environmental controls of community development of plant communities, the concurrence of diversity among plant, invertebrate, and amphibian species, and the structure of food webs for a group of wetlands that represent reference conditions of relatively undisturbed ecosystems. Based on preliminary evidence, we have developed a conceptual model to examine how climate change and land use change may affect wetland ecosystem function that ultimately links with the epidemiology of mosquito borne disease. Our initial objectives include: 1) determining the landscape change in wetland condition and identifying a continuum of condition classes; 2) developing a relative ranking of wetland condition based on habitat support of disease vectors and 3) developing a model of food web structure.

Keywords: mosquito-borne disease, ecosystem function and human health, isolated wetlands, food web

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The outbreak of carp disease caused by CyHV-3 as a model for new viral emerging diseases
*Moshe Kotler, Maya Ilouze, Maya Davidovich and Arnon Dishon
Hebrew University, Israel
Aquacultured koi and common carp (Cyprinus carpio) are intensively bred as ornamental and edible fish worldwide. Carp and koi farming industries have recently suffered enormous economic damage due to an epizootic disease caused by Cyprinus Herpes Virus-3 (CyHV-3) previously designated KHV. Although the emergence of a new virus rarely initiates a pandemic so severe that it reduces the life expectancy of a population, CyHV-3 is exceptional because of its enormous impact on the world carp population, resembling the global human influenza pandemic of 1918. High population density - large numbers of fish confined to a small area - is a major contributing factor to the epizootic desease caused by CyHV-3.
CyHV-3 is a large DNA virus, with a genome of ~295 Kbp, divergent from other mammalian, avian and reptile herpes viruses, but bearing several genes similar to CyHV-1, CyHV-2, IcHV-1 and RaHV-1. BLAST X analysis revealed that CyHV-3 genes encoded for proteins which are similar to, or exclusively present, in pox viruses. Thus, CyHV-3 is a novel virus, which contains genetic elements derived from pox, irido- and herpes viruses. Considering the phylogenic distance between CyHV-3 and higher vertebrate herpesviruses, and because of its unique characteristics, CyHV-3 represents the prototype of viruses assigned to the novel family Alloherpesviridae.
The lethal viral disease is observed, when water temperature ranges between 18o and 28oC. The virus is highly contagious and extremely virulent, but morbidity and mortality are restricted to koi and common carp populations. Mortality rates reach 90-100% of infected fish. Viral particles were revealed by electron microscopy in the intestinal and renal cells soon after infection. Histological analysis of fish revealed signs of interstitial nephritis as early as 2 days p.i. (post infection), increasing in severity up to 10 days p.i. Severe branchial pathology included inflammation in the gill filaments and loss of epithelial microridges. Minimal focal inflammation was noted in liver and brain.
CyHV-3 propagates efficiently in intestine and kidney. Viral antigens, DNA and infectious virus are easily detected in fish droppings by PCR, ELISA and by infection of cultured cells, indicating that the virus is disseminated and transmitted in culture ponds via droppings.
Fish, other than common carp and koi, are considered resistant to CyHV-3, although other researchers have reported that goldfish and grass carp are susceptible to the virus. We found that cultured cells of other cyprinids, such as silver carp and goldfish, allow CyHV-3 propagation, while cyprinid cells derived from fathead minnow are resistant.
In vitro cultured CyHV-3 infected cells, vacuolated and deformed, were converted to normal following shifting up of the temperature. Plaques disappeared and reappeared after transfer to non-permissive and permissive temperature, respectively. When infected cells maintained at 30oC are transferred to permissive conditions, viral mRNA synthesis proceeds in hierarchy, distinguished from that occurring in naive cells after infection. We suggest that the virus persists for long periods in the infected cells, enabling a new burst of virus production upon shifting into the permissive range.
Strategies for controlling viral infection in fish are of limited use. Preventing introduction of CyHV-3 into aquaculture facilities is desirable, but not fail-safe. Live attenuated virus was isolated in Israel and found to be an efficient and economic prophylactic vaccine. As an alternative, we developed a vaccine, which will circumvent many of the problems related to attenuated-live vaccine - inadvertent infection and reversion to the virulent strain.

Open questions: where is the viral agent preserved between seasons, and will vaccination help in eradicating the disease.

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KHV disease impacts on economics and culture
Masatomi Matsuoka
Asahi Fishermen's Union of Shiga Prefecture, Japan
Carp is common amongst most habitats in Japan, from north to south, living in canals, rivers and lakes. This is why most people are familiar with carp throughout the whole of Japan. We even use carp as a symbol of one of our National Holidays, 'The Children's Day'. On this day, many people put carp-shaped flags outside their houses to wish for the health and success of their children. Carp was probably chosen as a symbol, because people regularly caught sight of carp nurturing their young side by side in the wild. Japanese people also have the tradition of offering carp to god, and the fish has a sacred character. Therefore, carp is deeply routed in the hearts of our nation.
Lake Biwa is one of the most ancient lakes in the world, and supports a unique set of flora and fauna. For fish species, there are more than 50 species known to live in the lake, and 12 species are indigenous to the lake. Since carp is a special fish for the Japanese, it was a great deal of shock when we found tons of dead carp (100 thousand individuals) floating in the shores of Lake Biwa in 2004. The dead corpses gradually moved from the south to north of the lake, suggesting that it had something to do with the route of the spread of the virus. Even though this was a great catastrophic event for all fishermen in Lake Biwa, this is not really our utmost concern. Fish catch has been rapidly declining gradually since the 1970s and now there are only one fifth of fishermen left in Lake Biwa. Decreases in the number of fishermen makes it more difficult to keep Lake Biwa healthy. We think that the reason for the decline in all the fish species is related somehow to the outbreak of the KHV. Carp favor certain habitats in the littoral zone of the lake for spawning. This is a habitat where reeds grow, and where the water level is very low. Since the 1970s, we humans have been interfering with the lake system by controlling the water movement, and changing the structure of the littoral habitat. I feel that this may have had something to do with the decline in total fish catch. I especially feel that the ecotone zone between land and water is very important for the survival of all fish species. By finding the cause of the spread of KHV, I hope that we can ultimately figure out the real cause of the decline in all fish species in Lake Biwa.

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KHV-Carp-Human linkages: Case study in Lake Biwa, Japan
*Zen'ichiro Kawabata, Toshifumi Minamoto, Mie N. Honjo, Kimiko Uchii, Hiroki Yamanaka, Arata A. Suzuki, Yukihiro Kohmatsu and RIHN Environmental Disease Project co-researchers
Research Institute for Humanity and Nature, Japan
Research Background: The spread of emerging infectious diseases is becoming a serious global environmental problem. To predict outbreaks of infectious diseases and to prevent epidemics, it is essential not only to conduct pathological studies but also to understand the interactions between humans and environments that cause and spread infectious diseases.
Research Methods: Outbreaks of mass mortality in carp, which have long been part of human food resource and culture, caused by the koi herpes virus (KHV) disease have occurred worldwide since 1998. Specifically, we will focus on the relationships between environmental changes in a freshwater ecosystem, KHV, common carp (Cyprinus carpio carpio), KHV disease and humans. We regard this system as a model of interactions between pathogens and humans, because parameters common to other diseases are involved in the system and also this system allows us to conduct experiments to verify the interactions. Fields surveys are conducted at Lake Biwa, Japan.
Results and Discussions: It was found that heterogeneous topology, bottom quality, and water quality of satellite lakes which may affect the behavior of common carp. It was suggested by a mathematical model that lower connectivity among satellite lakes increases the stress carp experience and enhances the spread of KHV. We established a method to detect KHV in lake water that is indispensable to clarify KHV dynamics. Stable isotopic analyses identified their behavioral range. We developed a method to measure cortisol in water as a stress -induced hormone. We measured antibodies against KHV in blood and detected KHV in tissues of common carp. We have integrated these results into a part of the basic structure of the interactions between pathogens and humans. Specific researches required for revealing the linkage will be discussed.

Keywords: environmental alteration, KHV, carp, humans, linkages, disease model

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Environmental disease - environmental alteration and infectious disease -
Nobuyasu Yamaguchi and *Masao Nasu
Osaka University, Japan
Man has been altering environments to survive and to obtain safer and more comfortable life. For example, construction of drinking water and wastewater infrastructure is indispensable in civilized society and assured prevention of waterborne infectious diseases. On the other hand, excessive load on environments may disturb microbial ecosystems to cause outbreaks and expansion of infectious diseases.
To clarify the relation between environmental alteration and changes of microbial ecosystems will help to prevent infectious diseases. The aim of our study is to understand the linkage of "environmental alteration - disturbance on ecosystems - occurrence of infectious diseases - impact on human society". We will focus on Legionnaires' diseases and non-tuberculosis mycobacterium diseases from the viewpoint of environmental linkage.
Legionella spp. is ubiquitous in the natural environment though not abundant, while Legionella pneumophil has been increasing in artificial environments, such as cooling towers or spa etc., and caused outbreaks of Legionnaires' disease. In order to know hot spots and growth factors of L. pneumophila in artificial environments, we are trying to determine the abundance and genotype of L. pneumophila in Asian counties by using molecular microbial ecological methods.
Patients infected with non-tuberculosis Mycobacteria (NTM) have been increasing worldwide since 1990's. There are no precise and rapid detection methods of Mycobacterium in aquatic environments and infection route is still unclear. Recently, alteration of aquatic environments and disturbances on microbial ecosystems has been suspected as one of the causes of NTM diseases. Determining the hot spots of NTM and clarifying their dynamics in aquatic environments should be beneficial to prevent their infection to human beings.

Keywords: aquatic environment, environmental alteration, hot spot, Legionella, microbial ecosystem, non-tuberculosis Mycobacteria

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Malaria in tropical monsoon Asia
*Kazuhiko Moji1, Eiko Kaneda2 and Shusuke Nakazawa3
1) Research Institute for Humanitu and Nature, Japan, 2) University of Tokyo, 3) Nagasaki University Institute of Tropical Medicine, Japan
Situation of malaria in tropical monsoon Asia is overviewed with examples of field studies among ethnic minorities in Vietnam and Lao PDR. In most of the tropical monsoon Asian countries, malaria control has been successful since 1990s. For example reported malaria cases reduced from 226 to 37 thousand between 1992 and 2003 in Vietnam, from 54 to 19 thousand between 1997 and 2003 in Lao PDR. The rapid reduction was presumably due to malaria control efforts such as provision of insecticide-treated nets (ITNs), and early diagnosis and prompt effective treatment with the introduction of artemisinin-based combination therapy (ACT). Economic development, urbanization, and deforestation were also contributed directly and indirectly. This rapid reduction was occurred mainly in the areas where services were reachable and where ethnic majority were living. In the remote mountainous areas where ethnic minorities are living, prevalence and incidence of malaria are still high. In 2003, 83 school children between 6 and 10 yeas old in a village of ethnic minority in Binh Phuoc province, Vietnam were examined for malaria parasitemia for consecutive 5 weeks. Prevalence of malaria at week 0 was 36% by microscopy and 61% by PCR. The force of infection was 0.182 per week (95%CI: 0.149-0.220) for all kind of malaria and 0.111 per week (0.084-0.142) for P. falciparum. This means that children were infected to P.f 5.8 times a year and to malaria 9.5 times a year. Vector mosquitoes were bred in the small bushes in the absence of forest near the settlement, and poor structure of houses make female mosquitoes easier to suck on humans. In villages in Sepone district, Savannakhet province, Lao PDR, prevalence of malaria was 62%. Malaria control in the remote areas with the lifestyle of minorities in tropical monsoon Asia is to be discussed.

Keywords: malaria, tropical monsoon Asia, ethnic minorities, Lao PDR, Vietnam

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Epizootiology of avian influenza
Koichi Otsuki1,2
1) Kyoto Sangyo University, Japan, 2) Tottori University, Japan
Avian influenza is one of the most important zoonoses. Highly pathogenic avian influenza (HPAI) viruses subtype H5N1 continue to circulate and cause disease not only in free-living birds but also in domestic ones throughout Asia, Europe and Africa.
Free-living water fowls are considered the reservoir of all influenza A viruses. They are known to carry various subtypes of viruses including H5 and H7, but usually in the low pathogenic form. Considerable circumstantial evidence suggests that migratory birds can introduce low pathogenic H5 and H7 viruses to poultry flocks, which then mutate to the highly pathogenic form. Actually an avirulent H5N3 isolate from whistling swan became highly pathogenic after 24 consecutive passages through air sacs, followed by five passages in chick brain (Ito et al. 2001). This achievement proves clearly that highly pathogenic avian influenza viruses could arise from avirulent strains maintained in wild waterfowl. Origin of the present H5N1 influenza viruses is also thought to be an avirulent one harboured in some water fowl.
Avian influenza virus H5N1 subtype has been shown to transmit to humans and led to the fatal sporadic outbreak and has become threat to the public health.

Keywords: Highly pathogenic avian influenza; Low pathogenic avian influenza; influenza A virus; water fowl; Zoonosis

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The stress immunocompetency axis and the global decline of amphibians
Joseph M. Kiesecker
The Nature Conservancy, USA
Amphibians, a unique group of vertebrates containing over 6,300 known species, are threatened worldwide. A recent assessment found that nearly one-third (32%, 1856 species) of the world's amphibian species are threatened. Amphibians have existed on earth for over 300 million years, yet in just the last two decades there have been an alarming number of extinctions, nearly 168 species are believed to have gone extinct and at least 2,469 (43%) more have populations that are declining. Infectious diseases have been recognized as one major cause of worldwide amphibian population declines. This could be the result of the appearance of novel pathogens, or it could be that exposure to environmental stressors is increasing the susceptibility of amphibians to opportunistic pathogens. Here I will discuss the potential effects of stressors on amphibians, in the context of how stressors can alter disease susceptibility. I will present a series of case studies that illustrates the role of stress in disease outbreaks that have resulted in amphibian declines. First I will examine how elevated sea-surface temperatures in tropical Pacific since the mid-1970's, which have affected climate over much of the world, could be setting the stage for pathogen-mediated amphibian declines in many regions. Finally, I will discuss how the apparently rapid increase in the prevalence of amphibian limb deformities is linked to the synergistic effects of trematode infection and exposure to chemical contaminants.

Keywords: Global Amphibian Declines, Stress Mediated Infection, Climate Change, Pesticide Exposure

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Spatial and temporal drivers of West Nile virus outbreaks in North America
Shannon L. LaDeau
Smithsonian Migratory Bird Center, USA
The emergence of West Nile virus (WNV) in North America was marked by significant surprises, including the pathogen's rapid dispersal, millions of dead birds, and the largest human encephalitis outbreak ever documented in the Western Hemisphere. The spread of WNV across the North American continent preceded population-level declines in native avian communities, with local abundances of American crows approaching extirpation at some sites. Many of these bird populations remain diminished even eight years after the pathogen's arrival, signaling potential for altered avian communities and changes to long-term ecosystem function. Additionally, patterns of spatial and temporal heterogeneity in pathogen amplification are emerging, shifting ecological focus toward identifying the spatio-temporal drivers that have facilitated WNV establishment across the American landscape. Complex interactions between human land use and extreme weather may increase contact and amplification between mosquito vectors and avian hosts, though the spatial scale at which these interactions are operative is unclear. A better understanding of the dynamics that have facilitated WNV amplification and persistence may provide important insights into how vulnerable U.S. ecosystems are to the next emergent zoonotic disease.

Keywords: West Nile virus, heterogeneity, amplification, disease, population, avian

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Disease and aging in high-altitude Environments
*Kiyohito Okumiya1, Ryota Sakamoto1, Yasuyuki Kosaka1, Masayuki Ishine1, Taizo Wada2 and Kozo Matsubayashi2
1) Research Institute for Humanity and Nature, Japan, 2) Kyoto University, Japan
Highlands are the places where people have been building specific means of livelihood and unique cultures to survive in challenging environment with thin air and limited ecological resources over the years. The Himalaya/Tibet, the Andes and the Ethiopian Highland are three great examples of such highlands. Life, aging, and disease are closely-linked to lifestyle and environmental condition. Communities in the highlands have kept the interaction with those in lowlands in balance. However, in recent years, the wave of globalization has rushed over highlands, as symbolized by the infiltration of money economy, the acceleration of migration, the change of lifestyle and the extended life spans.
The three examples of human-nature relationship will be presented in each three major highlands. The survey was conducted on the relationship between health of highlanders and their economic condition in Yunnan Province in China. An increase in high-blood pressure and obesity was revealed, and susceptibility to lifestyle-based diseases was suggested. In spite of the acceleration of the aging phenomena, their subjective satisfaction of life and family relationship were higher than Japanese elderly.
5-10 % of highlanders over 2500m have the risk of suffering from chronic mountain sickness. Recently people with obesity are increasing in the Andes with the changes of lifestyles. Not only obesity but also aging are known to be the risk factors of chronic mountain sickness and the sickness may be increasing now.
The relationship between cultivation of maize and increase of malaria was disclosed recently by McCann JC in the Ethiopian Highland.
The aim of this presentation is to discuss the impact of changing natural conditions and lifestyles on life, aging, and disease. The change of natural ecosystems and cultures has accumulated in the human bodies through lifetimes. Aging and disease can be regarded as the environmental issues that affect the human bodies.

Keywords: highland, disease, aging, lifestyle, chronic mountain sickness

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Evolutionary control of infectious disease
Paul W. Ewald
University of Louisville, USA
Historically, epidemiology has been concerned with lowering the incidence of infectious disease by lowering the incidence of infection. Epidemiological interventions, however, have the potential to alter the evolution of target organisms, as is well known from the evolution of antibiotic resistance in response to antibiotic usage. Less obvious, but perhaps more important, are evolutionary effects on the harmfulness of pathogens. Interventions that force pathogens to evolve to less harmful states may benefit public health to a greater extent than expected from traditional nonevolutionary assessments. Evidence from the literature indicates that these effects have occurred inadvertently and may have been responsible for some of the great success stories in public health. This record emphasizes the need to develop public health policy that broadly considers evolutionary effects of epidemiological interventions.

Keywords: virulence, evolution, vaccination, AIDS, cholera, epidemiology, transmission diarrhea, diphtheria, pertussis

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Ecosystem health, global health and sustainability
David J. Rapport1,2
1) EcoHealth Consulting, Canada, 2) University of Western Ontario, Canada
The earth is in a tailspin, and this is no secret. All the global environmental assessments point in the same direction - down. The recently released ''Living Planet Inde'' tells the story of 'life' being extinguished at unprecedented rates. Global health requires a healthy planet, and with the spreading ecosystem pathology, the spread and emergence of diseases in humans are on the increase. The key challenge of global health today is to restore health to the world's ecosystems. Vaccines, antibiotics, and other 'quick fixes' are but stop-gap measures. They don't deal with the fundamentals: loss of soil fertility, loss of marine life, loss of potable water, and the worldwide epidemic in ecosystem distress syndrome (EDS). One of the key measures of EDS is increase in prevalence of disease. Humans, being part of the planetary ecosystems, are not exempt. This presentation will review some of the myriad connections between ecosystem health, global health, and the sustainability of life on the planet.

Keywords: Ecosystem Health, Ecosystem Distress Syndrome, Global Health, Sustainability, Ecology and Health