For the first time, researchers have tracked the movements of a wild duck infected with bird flu, information that could help them come up with disease mitigation strategies against the viral disease, said the U.S. Geological Survey (USGS) on Wednesday. More than 47.7 million birds in U.S. domestic flocks have died in outbreaks of highly pathogenic avian influenza (HPAI) since February, and losses are likely to exceed the record set in the 2014-15 epidemic, arguably the worst animal disease outbreak in U.S. history.
Bird flu has cut into egg production and driven up the price of turkey breast meat, as well as the price of holiday turkeys. More than 6 million turkeys have died of HPAI or been culled to prevent spread of the disease. HPAI can quickly wipe out a flock, so officials kill all the birds in an infected flock.
Europe has culled as many birds as the United States this year, and the European Center for Disease Prevention and Control said that the HPAI “epidemic season is the largest observed in Europe so far” and affects 37 countries. Bird flu has staged a fall resurgence in the United States after nearly disappearing during warm weather.
“We cannot predict exactly what we will see in the coming months or years. However, we believe it’s important for people to plan for an elevated risk from wild birds, especially during migration seasons,” said the Agriculture Department. “All bird owners should practice good biosecurity and keep wild birds away from poultry and other domestic birds.”
Waterfowl are often considered carriers of bird flu, which can be spread by direct contact between birds or through the droppings of infected birds. HPAI was confirmed in 644 samples from wild birds in the early months of this year, according to USDA data.
The infected duck was a lesser scaup, the most abundant diving duck in North America, with a range from Alaska to Central America. It was captured during research in the Chesapeake Bay region of Maryland and released before tests showed it carried the HPAI virus.
The scaup flew shorter distances than noninfected birds in similar time frames, said the USGS. The bird died of unknown causes three days after its release.
“This study provides insight on how movement patterns can change when a bird becomes infected, and this information is critical to understanding wild bird transmission of avian influenza,” said Diann Prosser, a research wildlife ecologist with the USGS and lead author of a study in the journal Transboundary and Emerging Diseases. “Analysis of movement data showed the infected bird’s maximum and average hourly movements were reduced when compared with noninfected birds.”
Even so, there were four instances of contact between the scaup and noninfected birds that were also being tracked, so there were opportunities for transmission despite the decreased range of the infected bird.
Some 43 million egg-laying hens and pullets and 7.4 million turkeys died in the 2014-15 HPAI epidemic.