Scientists Report Improvements in Predicting Avian Bird Flu
By David Sims, Institute for the Study of Earth, Oceans, and Space
March 26, 2008
In a paper published today in the Proceedings of the National Academy of Sciences
(PNAS), modeling results of highly pathogenic avian influenza (HPAI) subtype
H5N1 outbreaks in Southeast Asia suggest improved ways to predict where outbreaks
will most likely occur. This would have significant implications for disease
surveillance, risk management, and policymaking.
The study, detailed in the paper entitled “Mapping H5N1 highly pathogenic
avian influenza risk in Southeast Asia” and co-authored by UNH scientist
Xiangming Xiao, looked at how different risk factors contributed to the virus's
spread, including the numbers of ducks, geese, and chickens; human population
size; rice cultivation; and local topography. The results suggest that, of
this mix, people, ducks, and rice farming intensity are the dominant risk factors
in determining the distribution of H5N1 outbreaks in Southeast Asia.
Paddy rice farming in monsoon Southeast Asia varies substantially over space
and time. This poses a great challenge to gathering data about agricultural
land use, in particular, the cropping intensity and crop calendar. To address
this, the research team employs advanced satellite remote sensing technology
to map and track the spatial distribution and temporal dynamics of paddy rice
using images from the Moderate Resolution Imaging Spectroradiometer (MODIS)
sensor, part of NASA’s Earth Observing System (eospso.gsfc.nasa.gov).
Says Xiao, of the UNH Institute for the Study of Earth, Oceans, and Space
(EOS), “In Southeast Asia, double- and triple- paddy rice cultivation
in a year is often associated with free-grazing ducks. Our results show that
monitoring free-grazing duck populations and tracking paddy rice farming by
satellite are the most important and effective ways of predicting H5N1 outbreaks
These latest findings reported in the paper are the results from multi-year
research projects by an international team of interdisciplinary (e.g., animal
health, epidemiology, environmental remote sensing) scientists, including researchers
from UNH, the Universite Libre de Bruxells, Brussels, Belgium, and the Food
and Agriculture Organization (FAO) of the United Nations. The research projects
are funded by the FAO/UN and the U.S. National Institutes of Health Fogarty
International Center as part of the NIH/NSF Ecology of Infectious Disease Program.
Says Joshua Rosenthal of the Fogarty International Center at NIH, “Given
the potentially global scale of H5N1 Influenza, predictive tools, such as these
being developed by this research team, are an important part of our growing
capability to focus local surveillance and interventions to manage risks of
disease outbreaks in humans and on farms.
Adds Xiao, “Satellite-based Earth observations provide rich information
on the dynamics of ecosystems and landscapes, and assimilation of Earth observation,
in-situ surveillance data, and models offer powerful tools for our society
to better understand the ecology and epidemiology of animal-borne infectious
The paper can be read on the PNAS Early Edition site at http://www.pnas.org/papbyrecent.shtml.