Examining the Links Between Biodiversity and Human Health:

A Multidisciplinary Approach

The Biodiversity Crisis

Human actions are causing a biodiversity crisis, with species extinctions up to 1000 times higher than background rates

--Pimm et al. 1995

Biodiversity loss is accelerating

From WWF, “Living Planet Report,” 2004.

Proportion of threatened bird species (blue is highest) Davies et al. 2006

Best predictors of extinction risk are human impacts, such population density and agricultural activity.

Conservation priorities should focus on areas of high human density as well as best remaining habitat.

Global Decline

In Brasil, Mata Atlântica has declined by more than 90%.

Intensive deforestation causes massive species losses because new habitats cannot sustain viable populations of forest-dependent species

Golden-lion tamarin

Mata Atlântica

Ecosystem Servicesas provided by the diversity of life on earth

Supporting Services

Nutrient cycling Primary production Soil formation

Provisioning Services

FoodFreshwaterWood and fiberFuelClean AirMedicines

Regulating Services

Climate regulationFlood regulationDisease regulationWater purification

Cultural Services

AestheticCulturalRecreationalSpiritual

Ecosystem ServicesAs provided by the diversity of life on earth

Adapted from the Millennium Ecosystem Assessment, 2005.

Michellamine B African liana, Ancistrocladus korupensis, from Cameroon produces a novel anti-HIV compound. Significant amounts needed for preclinical investigation.

BryostatinThe bryozoan Bugula neritina has anticancer properties. With most of the world’s phyla, the oceans may be the medicine chest of 21st century

Chemical Diversity: The Imaginative Leap

60% of cancer drugs from natural compounds75% of drugs for infectious diseases from natural compounds

Chemical Diversity: The Imaginative Leap

Vacina de sapoCampinas Indian Reserve, Acre, Brasil. Shamans administered the kambô remedy, known as vacina de sapo or frog vaccine.

Collected by catching kambô, tying it spread- eagled between posts, and collecting slime from

its back. Frog is released and dried poison is rehydrated before application.

Potential applications include hypertension, strokes, and other illnesses. Profits to be shared with traditional users. World Bank estimates $65 billion potential from traditional medicines

The Third Epidemiologic Transition?

• First during transition to agriculture (10,000 yr BP)– Rise in infectious disease– Emerging zoonotics and increased virulence of human pathogens

• Second during Industrial Revolution (19th century)– Shift from infectious to chronic diseases– Increased water and air pollution linked to higher rates of cancer,

allergies, birth defects, and impeded mental development• Third during period of globalization and ecological collapse

– Rise of emerging and re-emerging diseases and antibiotic resistance

– Accelerated globalization of human disease ecologies

» Barret at al. 1998

New infectious diseases appear to be emerging

and re-emerging at a faster rate

Fauci 2006

75% of new infectious diseases are zoonotic in origin

How can a decline in biodiversity affect human health?

Disease emergence in past 30 years is primarily the result of social, demographic, and environmental transformation since World War II

Anthropogenic environmental changes drive infectious disease emergence throughout the continuum from humans to wildlife to domestic animals and within plant host populations

Vector-borne diseases, with much of their life cycle outside of the human host, may be most sensitive to change in environmental conditions

Biodiversity and West Nile Virus

Mosquito-borne disease; wild birds serve as the primary reservoir hosts

Factors accounting for variation in WNV prevalence are poorly known

Ezenwa et al (2006) examined the diversity of bird reservoirs in association with West Nile virus infection in mosquitoes across Louisiana.

Infection rates of Culex mosquitoes declined with increase of nonpasserine species richness

The lower infection rates were correlated with lower numbers of human cases of West Nile virus.

Links between high biodiversity and reduced disease risk may help account for distribution patterns

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tick

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Ostfeld and LoGiudice 2003

Reduced reservoir biodiversity correlates with increased risk of Lyme disease transmission to humans and may be a general rule of frequency-dependent transmission

Biodiversity and Lyme disease

Mammalian species from squirrels (Sq) to skunks (Sk) can reduce the effect of white-footed mice, the most competent reservoir of Lyme disease, on tick infection.

90% of ticks feeding on white-footed mice become infected with Lyme bacterium

Only 15% of ticks feeding on squirrels become infected with Lyme bacterium

Species richness may be only part of the problem, abundance also plays a role

LoGuidice et al. 2003

Conditions for dilution effect

• Generalist vector• Variation in reservoir competence among hosts• Positive correlation between reservoir competence and percentage of tick meals supplied by hosts in the community Logiudice et al. 2003

Deforested sites in the Peruvian Amazon had greater mosquito (A. darlingi) transmission rates of malaria compared to sites with less habitat alteration. Biting rates were 278 times higher in deforested areas than rates for forests

Deforestation and Spread of Vector-Borne Diseases

Vittor et al. 2006

Low biting rate

High biting rate

% Forest in 2 x 2 km grid

Loss of biodiversity increases the frequency of interspecific interactions, in turn increasing pathogen transmission

Intensity of gastrointestinal parasite infection is elevated in red colobus monkeys inhabiting forest fragments with reduced plant biodiversity and high rates of human encroachment (Golberg & Gillespie)

High levels of antibiotic resistance in bacteria from chimpanzees in locations where humans have been encroaching upon their habitats

Forest fragmentation and disease transmission

Biodiversity change in forest systems

• Bat populations deprived of their

primary food sources sought alternative hosts:

humans

• In rural areas, shift occurred when pigs and cattle were

eliminated

• Massive attacks occurred in gold mining camps of

Amazon when food sources were depleted because

of overhunting and noise (Confalonieri 2001)

Wildlife Trade and Disease Emergence

Consumption of wild animal meatCentral Africa: more that 1 billion kg per yearAmazon Basin: 67-164 million kg per year

approximately 6.4 to 15.7 million animals

Outbreaks, including SARS, have caused hundreds of billions of dollars of economic damage globally

One regulatory approach is to decrease the rate of contact among species at this interface created by wildlife trade

Karesh et al 2005

Projected spread of Ae aegyptii, dengue vector, in Australia by 2050McMichael et al. 2006

Present2050

Global Warming and Spread of Vector-Borne Disease

Biodiversity-Health Research at US Environmental Protection Agency

• Exploratory research funding • How do anthropogenic drivers of changes in

biodiversity directly affect the transmission of human disease?

• What are the mechanisms that connect these issues?

• Multidisciplinary approach to exploring root causes of disease emergence and spread to assist in prevention and mitigation

Workshop on Biodiversity and Human Health

Sept. 14-15, 2006, at Smithsonian Institution Washington, DC

Convene interdisciplinary workshop of researchers, practitioners, and decision makers in ecology, public health, social sciences, and remote sensing to discuss• the state of the science

• important research priorities

• risk analysis and creation of monitoring and forecasting network

• types of data and models needed to map the relationship between biodiversity decline and EIDs

Partners and Collaborators

Yale Center for EcoEpidemiology

Institute of Ecosystem Studies

Asia-Pacific Institute of Tropical Medicine and Infectious

Diseases

National Oceanic and Atmospheric Administration

(NOAA)

NASA Ames Research Center

World Federation of Public Health Associations

American Public Health Association (APHA)

World Health Organization (WHO)

Smithsonian Institution

Protecting biodiversity, protecting human health

Environmental factors contribute to emerging diseases and environmental approaches can reduce their burden

Develop new tools to integrate data for improved understanding of relationships between biodiversity and human health

Use earth observation and field data to track and analyze global relationships between habitat alteration, biodiversity loss, vector ecology, and the emergence and spread of infectious disease

Inform decision-making to benefit society

Develop new constituency, momentum, and approaches for conserving biodiversity and protecting endangered species