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HealthNet Offers Bird's Eye View of West Nile Virus

Borne by mosquitoes that feed on infected birds, West Nile Virus can kill people by causing inflammation of the brain (encephalitis) or of the membranes that cover the brain or spinal cord (meningitis). About one in 50 people who exhibit symptoms from West Nile Virus will develop health effects that could include encephalitis or meningitis. In 2005, 12 people died in Canada from the virus.

Combating West Nile and protecting Canadians requires knowing where and when the virus is spreading. With these objectives in mind, the Public Health Agency of Canada (PHAC) recently developed a web-mapping application to better track and analyze the locations of dead birds infected with the West Nile Virus.

Known as HealthNet, this web-mapping application takes advantage of the Canadian Geospatial Data Infrastructure (CGDI) and its common data and service standards. Through the Internet, HealthNet users can tap into a multitude of CGDI-compliant data sources. These interoperable data sources allow users to better understand where dead birds are showing up and what threat they present.

"HealthNet is a marvellous resource," said Dr. Peter Buck, epidemiologist and section manager with the Foodborne, Waterborne, and Zoonotic Infections Division of PHAC. "It equips us to answer questions such as, 'What do these dead birds in this situation mean?' and 'How do we interpret this data?'"

HealthNet serves those itching for greater insight

Using the CGDI's standard Web Mapping Service, someone could plot the locations of dead birds on a web map and then add several more CGDI-compliant geographic data layers housed in a variety of databases. One layer might portray ground cover—is it swampland? Forest? Urban? Parkland? Another layer might reveal population density—where are the nearest towns or communities? These types of integrated views allow health professionals to assess the West Nile risks to Canadians more completely.

"If the dead birds are concentrated in an area heavily populated by humans, we can educate the public and consider potential control activities," said Dr. Buck. "Or if the birds are in the middle of nowhere, we may not need to worry about it because the risk of infection is low. In those cases, we might simply tell people that if they're canoeing in the area to think about using insect repellent."

Multifaceted partners give HealthNet ample heft

GeoConnections contributed $105,000 in funding and technical support to HealthNet, but the venture relied on many other partners as well including the Canadian Cooperative Wildlife Health Centre, the Canadian Network for Public Health Intelligence, the Epidemiology Services Group within the BC Centre for Disease Control, GeoTango International Corp., the Nova Scotia Department of Natural Resources, the Office of Public Health Practice (the GIS body within the Public Health Agency of Canada dedicated to warehousing spatial data), the Public Health Agency of Canada, and York University in Toronto.

Thanks to the contributions and cooperation of these partners, people no longer have to find and buy geographic data, put it on CDs, load it onto their PCs, and map it. Instead, they can access health data through the CGDI and generate maps using its Web Mapping Services.

CGDI data standards illuminate a two-way street

Just as HealthNet users can overlay data from other sources onto their dead-bird data, so too can others integrate dead-bird data into their maps—another benefit of CGDI data standards. "This capability means that people with different interests can access either dead-bird data or other data and plot it together to see if any meaningful patterns emerge, spatially or temporally," said Dr. Buck. "It's a two-way street."

From the outset, the PHAC wanted to streamline and automate its analysis of dead-bird data. Before the advent of HealthNet, PHAC analysts would spend a day producing dead-bird maps, an onerous process that involved multiple steps. And analysts were stuck with a static map: if they wanted to examine another time period or location, they would have to start from scratch. With HealthNet, however, analysts can generate dead-bird maps simply by clicking buttons on their web browsers. "The process is fully automated," said Dr. Buck. "If you don't like what you see, you can easily look at a different time period."

The system needed to be easy to use too. Few local health units have medical geographers or geographic information systems (GIS) specialists on staff to produce maps. Anyone moderately familiar with computers can use HealthNet. "People don't need GIS training or a major geography background," said Dr. Buck. "HealthNet offers them a very simple and useful way to understand their data and map their information without huge resource implications."

Although the chances of contracting West Nile Virus are extremely low, any virus that can kill has to be treated seriously. HealthNet gives Canada's health practitioners a convenient tool to monitor the virus and lessen its potential damage.

To use HealthNet, go to http://www.westnilevirus.gc.ca/.

Partners include: BC Centre for Disease Control Society, Canadian Cooperative Wildlife Health Centre, GeoTango, Natural Resources Canada-GeoConnections, Nova Scotia Department of Natural Resources—Wildlife Division, Public Health Agency of Canada, York University

GeoConnections is a national partnership initiative to evolve and expand the Canadian Geospatial Data Infrastructure.