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Understanding waterfowl patterns to assess risk of bird flu

The Delmarva Peninsula lies under the Atlantic Migratory flyway, a path waterfowl migrate through. As Europe deals with recent outbreaks of a severe strain of Avian Influenza, some local poultry growers worry that just one infected bird passing through the region could contaminate and kill whole flocks of chickens.

That’s why poultry growers across Delmarva take precautions to avoid the possibility of the virus traveling from outside of the farm to the respiratory systems of their chickens. And research is being done that could help farmers better understand waterfowl patterns so they can prepare for when the virus surfaces.

Before Georgie Cartanza can check on her chickens at her Dover farm, she has to disinfect. She zips up a pair of disposable coveralls, veils her hair underneath a hair net, steps in dry chlorine and applies hand sanitizer. It’s all part of biosecurity to protect chickens at her farm from disease - including deadly strains of bird flu.

Delmarva has not seen a fatal case of bird flu in over 10 years; but the devastation it could bring keeps farmers like Cartanza on their toes. The virus naturally occurs in waterfowl, but if a highly pathogenic form gets into a chicken’s respiratory system, it could cause severe disease and increased mortality. And with every breath, one chicken can spread it to the rest of the flock.

Georgie Cartanza’s chicken farm

"The reality is right now we go in with the mindset that it’s here and we’ve got to prevent it from getting in here," Cartanza said. "We assume that any migratory bird can be a carrier."

Delaware’s State Veterinarian Heather Hirst said with the Highly Pathogenic Avian Influenza - a highly fatal form of the flu now in Europe and the Middle East - that's the right approach.

"Wild birds migrate and can carry the virus in their feces," Hirst said. "And so wherever they fly over, they can introduce the virus to domestic poultry. Just because the highly pathogenic flu is in Europe and the Middle East doesn’t mean those birds can’t travel over here this winter or next winter and spread the same virus to our birds."

Part of the reason poultry farmers are always taking precautions to prevent the possibility of the Avian Flu from coming to their farms is because an outbreak in the 4,700 chicken houses across Delmarva could shut down the region’s $3.2 billion dollar poultry industry. Maryland State Veterinarian Michael Radebaugh said if an extreme case like that happened, it could even close trade overseas.

A sign showing biosecurity awareness on of Georgie Cartanza’s farm

"It only takes one duck that is infected with this virus who is not showing any signs - a grain of fecal material in that duck that’s infected with the virus - can spread to one million birds," Radebaugh said.

So understanding the comings and goings of waterfowl is crucial, and that’s what University of Delaware and University of California Davis researchers are trying to do. University of Delaware wildlife ecology professor Jeff Buler said the group is using weather surveillance radar to chart migration - following waterfowl like a meteorologist watches precipitation moving.

"One idea is we could use it to basically have a risk threat assessment based on where the waterfowl are located in certain areas, that could alert farmers to know, ‘your farm is at a high risk now because there are waterfowl located near your farm," Buler said.

This research is mostly being done in California but the team conducted a preliminary trial in Delaware.

"We identified six hotspot locations of where waterfowl tend to congregate here in Delaware," Buler said.

"Radar reflectivity depicting the average densities of waterfowl gathered in agricultural fields and wetlands during the winter of 2014-2015 near Sacramento, CA."

"Radar reflectivity depicting the average densities of waterfowl gathered in agricultural fields and wetlands during the winter of 2014-2015 near Sacramento, CA.”

One of those is Bombay Hook - just 10 miles from Cartanza’s poultry farm in Dover. Another hotspot is the Choptank River along Maryland’s eastern shore.

Buler said it’s the first time weather radar is being used in a disease ecology framework, and Georgie Cartanza said it sounds like it could help her Dover farm.

"We may learn the behaviors of the birds and it may also help us, to me, track if the Midwest has had an outbreak and it was as devastating as it was - what was different about the patterns of those birds that it didn’t get here?" Cartanza said.

But Buler points out the virus isn’t only spread by waterfowl. "Bridge species" are species that travel between wetlands and farms, and those species, like mice and rats, could carry the virus from waterfowl to chickens.

Buler said his team would like to study those species’ movements next. And it could ultimately keep farms on Delmarva like Cartanza’s - and the region’s poultry industry - aware of the possible spread of bird flu.

Chesapeake: A Journalism Collaborative is funded with grant support from the Clayton Baker Trust, The Bancroft Foundation, Michael and Ann Hankin, The Jim and Patty Rouse Foundation, The Rob and Elizabeth Tyler Foundation, and the Mid-Shore Community Foundation.

USDA Avian Flu Guidance by Delaware Public Media on Scribd