Friday, April 9, 1999

MATH MODELS LINK EL NINO AND CHOLERA; WILL ALSO AID FISH COUNTS

WASHINGTON, D.C. --The theory that ocean warming related to El Nino can affect outbreaks of cholera is upheld by early results of new mathematical models, Dr. Mercedes Pascual, a University of Maryland Biotechnology Institute (UMBI) researcher said today (Friday, April 9) at the National Academy of Sciences.

Pascual, a mathematical ecologist, spoke at the Academy where she accepted a $1 million Centennial Research Fellowship from the James S. McDonnell Foundation. The fellowship will help Pascual continue to ply sophisticated mathematics into complex problems in marine ecology.

Some of Pascual’s models could help untangle how epidemics of cholera or other human diseases are influenced by climate changes. Others will help scientists better predict fluctuations in the populations of commercially harvested species of fish.

Pascual, 38, a research assistant professor at UMBI's Center of Marine Biotechnology (COMB) in Baltimore, Md., is one of ten early career scientists being honored at a special NAS symposium, Thursday and Friday, April 8 and 9 for receiving $1 million McDonnell fellowships.

Uses of mathematical models span many fields of science, including the common five-day weather forecasts for television newscasts and government estimates of future U.S. economic growth.

Pascual designs her models to show how marine organisms change over time and across different scales of space. The challenge, said Pascual, is finding ways to understand and predict dynamic changes due to a great many variables in marine ecology. For example, Pascual’s cholera models portray patterns in how the number of cholera cases have changed over time in relation to climate. By including climate information, a model may help local authorities using short-term weather forecasts to set up timely prevention and treatment programs.

The marine bacteria, Vibrio cholerae, has caused cholera epidemics at least since Biblical times by infecting the human gut, likely through drinking water, then triggering the highly contagious disease. Pascual’s early results on cholera models uphold previous studies of cholera ecology by COMB microbiologist and National Science Foundation Director Rita Colwell and Dr. Anwar Huq, also a COMB microbiolgist.

There is a "growing ecological perspective" in studies of cholera, she said, but still no one knows how to predict (a pattern) of outbreaks based on climate variables, such as rainfall or water temperature. "Nonlinear ecological models are important to better understand and predict the complex interplay of biological processes and the external environment," she said. Human epidemiology has a long data record of cholera epidemics that is available for ecology research, she added, but the environment also seems to play a big part in disease epidemics.

Developing mathematical models of fisheries will tap into a renewed interest in studying the effects of the environment by fisheries scientists, said Pascual. "But, as with human epidemiology, exact predictions in fisheries remain difficult, if not, elusive goals. I will use part of the fellowship to organize a workshop to bring together scientists who develop theoretical models with fish ecologists."

Pascual, originally from Uruguay, remembers first enjoying marine biology as a child when she and her civil engineer father would travel to the Atlantic coast to snorkel dive. She began college studies in marine biology while living in Rio de Janeiro, Brazil. She graduated from the Universidad de Ciencias Exactas y Naturales in Buenos Aires, Argentina. Pascual received a master’s degree in mathematics from New Mexico State University and a Ph.D in biological oceanography from the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program.

On receiving the fellowship, Pascual said, "I think this is very exciting but on the other hand it will be a big responsibility. This award is very special because of its long-term funding commitment. It provides an extraordinary opportunity."