Ecology of diseases
Dr. Bhoj R singh, Principal Scientist (VM)
I/C Epidemiology; Centre for Animal Disease Research and Diagnosis
Indian Veterinary Research Institute, Izatnagar-243122, Bareilly, UP, India.
• Ecology (Greek: οἶκος, "house"; -λογία, "study
of”) is the scientific study of interactions among
organisms and their environment.
• Interactions which organisms have with each
other (biotic) and with their abiotic environment.
• Ecology also deals with the
diversity, distribution, amount
(biomass), number (popultion) of organisms, as
well as competition between them within and
• The ecology of infectious disease is an important, growing sub-discipline of
ecology that combines field studies, epidemiology, molecular
approaches, and modeling to understand interactions among wildlife
hosts, vectors, and pathogens, and to better forecast risk of disease." (Paul
Stapp, from EcoHealth 4:121�124)
• The study of the underlying principles that influence the spatio-temporal
patterns of diseases. Incidence, spatial distribution, and timing of diseases
reflect the interactions of populations with each other. Diseases may be
environmental (i.e., caused by things like toxins, cancers, environmental
shortages such as famine), or infectious (i.e., caused by pathogens).
• The interaction of the behaviour and ecology of hosts with the biology of
pathogens, as it relates to the impact of diseases on populations. (Sci-Tech
• The study how hosts and pathogens interact in populations, communities
and even entire ecosystems." (Les Real, Emory University)
• Disease ecology is interdisciplinary field that necessarily involves the
microbiology, ecology, genetics, geography, medicine, mathematics and
epidemiology to better understand how climate and environment affects
the interaction between hosts and pathogens." (Margie Lee, University of
• Many diseases are result of filing to understand ecology of
diseases, disturbing the ecosystem without knowing the
consequences viz., Plague, Malaria, AIDS, Ebola, West Nile,
SARS, Lyme disease and hundreds more.
• Any emerging disease in the last 30 or 40 years has come
about as a result of encroachment into wild lands and
changes in demography, says Peter Daszak, a disease
ecologist and the president of EcoHealth.
• Sixty percent of emerging infectious diseases that affect
humans are zoonotic — they originate in animals. And
more than two-thirds of those originate in wildlife.
• Why do the patterns of disease occur as they do?
Conceptual: what variables are important?
• To figure out, the ways in which people alter the landscape — with
a new farm or road, for example — where the next diseases are
likely to spill over into humans and how to spot them when they do
emerge, before they can spread.
• To study the interaction of the behaviour and ecology of hosts with
the biology of pathogens, as it relates to the impact of diseases on
• The environmental impact assessment (EIA)
• EIA has three main functions:
• • to predict problems,
• to find ways to avoid them, and
• to enhance positive effects.
What is the challenge and areas of
research in ecology of diseases?
• The challenge is to understand
– Ecological and evolutionary aspects of infectious diseases;
– Develop an understanding of the interactions among
pathogens, hosts/receptors, and the environment;
– To make it possible to prevent changes in the infectivity and
virulence of organisms that threaten plant, animal, and human
health at the population level.
Important research areas include:
– Examining the effects of environmental changes as selection
agents on pathogen virulence and host resistance;
– Exploring the impacts of environmental change on disease
aetiology, vectors, and toxic organisms;
– Developing new approaches to surveillance and monitoring;
– Improving theoretical models of host-pathogen ecology."
How it is different?
• Differs from a traditional medical approach in
that it’s not concerned with describing the
pathology of individuals
• „ Differs from epidemiology in that the emphasis
is on general processes of population
interactions rather than characterization of
• Populations are systems of organisms interacting with and in the
environment, and these interactions result in emergent properties.
• Emergent properties: outcomes of higher-order interactions among
components of a system that can’t be anticipated by studying the
components in isolation
Example: can the introduction of an efficacious.
vaccine actually make a disease situation worse?
• Basic concept of disease ecology is related to the niche.
• Niche: those sets of biotic and abiotic conditions in the
environment that define the limit of a species’ ability to survive.
• „ In disease ecology, the dynamics of infectious disease are viewed
as the overlap in time-space of niches of the component
• Spatio-temporal fluctuations in niche overlap affects disease rates
Disease ecology in News
• Climate Change and Disease Ecology, Science Daily, August 15, 2007
• Employing Ecology to Predict and Manage Infectious Diseases, Science
Daily, May 10, 2005
• When Animals Sound a Warning. Yale Medicine, Spring 2006
• Grad Specialization Created in Wildlife Disease Ecology. MSU News
Bulletin, October 24, 2002
• WA Govt Urged to Invest More in Wildlife Disease Research. ABC
Perth, July 13, 2007
• Conference Signals Growth of Disease Ecology Field. Emory Report, June
• UGA symposium explores the role of climate and ecology on infectious
disease. UGA Press Release, March 29, 2007
• UGA to inaugurate new lecture series on infectious disease ecology. UGA
Press Release, March 21, 2006
• Amphibian Declines, Disease Ecology, Biodiversity Are Highlighted at
Conference. NSF Press Release, August 8, 2006
• Infectious Disease Ecology: Effects of
Ecosystems on Disease and of Disease on
Ecosystems . Eds. Richard S. Ostfeld, Felicia
Keesing, Valerie T. Eviner. Princeton University
Press, Princeton and Oxford
• The Ecology of Wildlife Diseases. Peter J.
Hudson. Oxford University Press, Oxford.