[spacer] Gateway Flag [top]
Gateway Flag [middle]
[spacer]   [grey line] Gateway Flag [bottom]
Current issue

Wanna volunteer?
About this site


Gateway Blog
Edmonton Journal
Globe and Mail
National Post
BBC News
New York Times
Washington Post
Google Search
The Onion

New model helps swat West Nile virus

Jeffrey Greeniaus
U of A researchers are exploring ways to prevent West Nile virus outbreaks.

Using biology, mathematics, and computers, three U of A researchers have found a way to swat outbreaks of the mosquito-borne West Nile virus before they take off.

Scientists first discovered West Nile virus (WNv) in Uganda in 1937, and for many years it remained isolated to the African region. In 1999, an outbreak of the virus occurred in New York. From there, migrating birds carried it north to southern Ontario by summer 2002, and then to Alberta by July 2003. Although it kills under 0.1 per cent of humans that it infects, the virus can cause fever, meningitis, and encephalitis.

Dr Mark Lewis, Dr Marjorie Wonham and Tomas de-Camino-Beck, all from the U of A’s Centre for Mathematical Biology, hope their new mathematical model will help North Americans prevent an outbreak of WNv here.

The researchers wanted to know what conditions produced the New York City outbreak. An outbreak, explained Lewis, occurs whenever a given instance of a disease produces one or more subsequent infections in other creatures.

Scientists knew the WNv spread from birds to horses and humans via mosquitoes, but didn’t know how many mosquitoes or birds had to be eliminated to stop it.

The critical factor turned out to be the ratio of birds to mosquitoes. Mosquitoes transmit the virus, said Wonham, while birds merely contain it.

Keep the mosquito population below a certain outbreak threshold, and the virus will stay under control, she explained.

“But there’s an open question about birds, whether removing birds would do the same thing,” she explained.

To their surprise, the researchers found decreasing the number of birds in their simulated experiment actually increased the chance of a West Nile outbreak.

“By killing birds, the ones that are left are bitten even more,” thus causing the virus to spread faster, explained Lewis.

What do these results mean? According to Lewis, it means cities don’t have to use massive amounts of expensive, environmentally hazardous pesticides.

“You don’t have to kill all the mosquitoes to get rid of the disease. You just have to bring them down to a threshold level, after which the disease will die out on its own. You don’t have to spray everywhere and get rid of all the wetlands.”

The computer model, coded by de-Camino-Beck, can help any region calculate their unique outbreak threshold. However, Lewis cautions that even if mosquitoes are kept below this outbreak threshold, it will still take many years for the virus to die out. In other words, the model can prevent, but not stop, an outbreak.

Nor have they finished working on it, he added. The team wants to add a spatial control to the model.

“You can’t control [mosquitoes] everywhere,” said Lewis.

“We’re trying to calculate the size of a buffer zone around a city that would be necessary to prevent the disease from coming in from the outside.”

Expanding it to include multiple species of bird and mosquito (instead of the one apiece used now) and long-term climatic and geographic data would also make the model more effective.

Biologists have used models like this one for years.

“It turns out that people have been using mathematical models for diseases for almost a century now,” said Lewis, noting how one such model was used to study malaria in the 1930s. “In the field of epidemiology, these models have worked extremely well.”

As models become more and more complex, interdisciplinary projects like the Centre for Mathematical Biology have become more and more common.

“I’m a mathematician,” said Lewis.

“Marjorie’s a biologist, and Tomas is a computer scientist. Together we’ve created something that none of us could have done individually.”

“Biology by itself has its limits,” Wonham agreed.

“And math by itself has its limits. But when you put both of them together, you can constantly go back and forth and get a fruitful cross-pollination of knowledge.”

Wanna respond? Send your feedback to gateway@gateway.ualberta.ca.
[grey line]
Thursday, 29 January, 2004
Volume XCIII Issue 31

[grey line]
Advanced search
[grey line]
Activist sparks controversy among campus Muslims
New model helps swat West Nile virus
International research may solve mad cow mystery
Campus crime beat
Campaign teaches kids to Butt Out before they start
'World-class' heart institute to open on campus

[grey line]
Editorial: Start caring about the SU right now
Downtown Woes
Editorial Cartoon
US election may provide some answers about 11 September
Criticize Stronach for her campaign, not sex
Stereotypes got you those pants, jerk
University’s hidden course fee not playing by the rules
Dave Alexander's Top Ten

[grey line]
Pandas basketball playoff run still alive
Hockey Bears look to clinch first place this weekend
The Pep Rally
Point: Oilers all-star omission is a sign of bleak times
Counterpoint: All-Star game is stupid anyway

[grey line]
Interview with a werewolf
Butterfly Effect proves Kutcher isn’t actually a dumbass
Nothing too cerebral for Time Circus
Film explores the fine line between activism and terrorism
Old age a time for dissatisfaction, cynicism and pondering death

[grey line]
Japanese Idol

[grey line]
[spacer] [spacer] © 2002 Gateway Student Journalism Society -- All rights reserved | This site uses valid CSS