Days after a deadly, contagious strain of bird flu was found on a Lancaster County poultry operation, Don Ranck spoke with a farmer who was open about the anxiety he felt every time a wild bird flew over his chicken houses.
Any wild bird passing overhead could be infected, and tainted droppings could spread the illness to his flock, the farmer feared, according to Ranck, vice president of the Lancaster County Farm Bureau.
“There are so many unknowns. There are so many ducks flying over, and any of them can carry it, ”Ranck said.
In fact, scientists say they believe the virus – a strain of avian influenza that is highly lethal and contagious in poultry – made its way to the United States via wild waterfowl migrating from Europe.
Now, even though much of the spring waterfowl migration season has come to a close in Pennsylvania, local experts believe the virus likely has spread to and is circulating within a number of the state’s native, year-round bird species.
That means local poultry farmers must continue to be vigilant to limit their flocks’ exposure to wild birds.
“We do not know how soon it will be before this particular outbreak resolves,” said Andrew Di Salvo, a wildlife veterinarian with the state Game Commission.
Not closely monitored
As of Tuesday, the virus had been detected in just eight wild birds in Pennsylvania – two bald eagles, five hooded merganser ducks, and one redhead duck, according to Game Commission officials.
None of the birds were discovered in Lancaster County.
The closest was a dead bald eagle discovered in neighboring Chester County, the first of the state’s virus-positive birds, which was confirmed in mid-March. The others were found in northwestern Pennsylvania, specifically Clarion, Crawford and Venango counties.
Just eight wild birds may seem few, but confirmed numbers likely are deceiving, Di Salvo said.
“Our wildlife health surveillance is not uniform throughout the Commonwealth,” he said in an email, explaining that it’s much harder to detect sick birds in remote areas. “It’s very much biased to where people live as they often contact us with reports of sick / dead wildlife.”
For a more accurate assessment of wild bird flu cases, Di Salvo pointed to numbers recorded nationwide, including hundreds of infections along the East Coast.
As of Wednesday, highly pathogenic avian influenza had been detected in at least 899 wild birds across 34 states, according to figures from the US Centers For Disease Control and Prevention.
Again, Di Salvo offered perspective when it comes to cases in Pennsylvania.
“If we are not testing birds in an area, that does not mean that the disease is not there. … It is much more accurate to assume the disease is present in wild birds throughout the entirety of the Commonwealth, ”he said.
Waterfowl are among species considered highly susceptible to the current outbreak of avian flu, and recent migrations through the area have had agriculture officials on high alert.
Avian influenza is most commonly spread when healthy birds come in contact with bodily fluids from other infected birds, wild or domestic, experts have said.
That type of contact likely has occurred among local wild birds since the current strain of avian influenza was first confirmed in the United States in December, according to a pair of biologists at Millersville University.
For example, a virus-positive duck could have defecated in a water source used by other birds, spreading the infection, according to Eric Ryndock, an assistant professor of biology at the university, who specializes in virology.
Or a predator like a bald eagle could have hunted and consumed an infected bird migrating through the area, contracting the disease in the process, said Aaron Haines, an associate professor of conservation biology, specializing in wildlife management.
“Eagles are here all year, and they feed on waterfowl,” he said. “I think there is potential for it to continue spreading within our local birds here.”
That’s a problem for poultry and egg farmers, agriculture officials have said, because infected wild birds can fly over and land near chicken houses and other facilities. There they can directly infect poultry – including chickens, ducks, geese, quail, pheasants, guinea fowl and turkeys. Or the wild birds can secrete bodily fluids that contaminate farmers’ clothing and equipment, on which the virus is later carried to poultry animals.
Wild birds more robust
Because of those threats, experts have encouraged farmers and backyard poultry growers to increase biosecurity measures to protect their flocks. They include limiting nonessential access to farms; regularly cleaning farm-related clothing and equipment; not sharing equipment with other farms; and stepping up sanitizing of personnel and vehicles on farms.
Still, by Thursday afternoon, the virus had been found in flocks on six Lancaster County poultry operations, requiring the destruction of 3,825,800 birds – a combination of egg layers, meat birds and pullets. Nationwide, the illness had infected 247 flocks across 29 states, affecting 35.52 million commercial or backyard poultry birds, according to the US Department of Agriculture
Most of those birds were euthanized primarily in an effort to curb the virus’s further spread. Killing the birds is also believed to be more humane than letting poultry suffer with the flu.
“You are going to have severe respiratory situations,” Ryndock said, referring to the illness in poultry.
In birds, symptoms include reduced coordination, diarrhea, nasal discharge, decreased or abnormal egg-laying, lack of energy, lack of appetite and even sudden death.
However, Haines said wild birds seem more “robust,” or more capable of handling the illness, which means symptoms may be less severe, allowing them to more easily move around while infected.
That’s likely already the case, according to Sean Murphy, state ornithologist with the Game Commission.
“It’s out there on our landscape,” Murphy said.
Stressing that point, Murphy named just a few of the native wild bird species that he knows are susceptible to the illness, including predators like red-tailed hawks, great horned owls, bald eagles and Cooper’s hawks.
“There are plenty of those that are here year-round,” he said.
If there is any good news, it’s that many migrating waterfowl are already gone from the area, and temperatures are starting to warm, multiple experts said.
“Disease transmission should decrease with lower bird densities, plus this virus cannot survive for long at room temperature or higher,” said Di Salvo, the veterinary commission.
Rydnock added that humid summer air will make it more difficult for airborne virus droplets to travel
Humidity and changing temperatures, however, will have little impact on transmissions through direct contact with bodily fluids like infected-bird feces, he said.
“I think that could be a factor that might keep it going through the summer,” Rydnock said.
Dan Ardia, a professor of biology at Franklin & Marshall College, agreed, especially when it comes to infections in poultry houses, where climate is at least somewhat controlled and birds are often stacked and crowded, causing stress that can lower immune systems.
“Housing conditions, they do not change year-to-year, month-to-month,” Ardia said.
In rare cases, humans have contracted avian flu, but experts, including at the CDC, have said this outbreak poses a low risk to people.
Earlier this spring, commission officials said people should be cautious while interacting with wild birds.
“Always observe wildlife from a safe distance. Avoid contacting surfaces that may be contaminated with feces from wild or domestic birds. Do not handle wildlife unless you are hunting, trapping, or otherwise authorized to do so, ”officials said, adding that even those authorized to handle wildlife should wear personal protective equipment.
Previously, commission officials have asked people who encounter sick or dead wild birds to report them at 610-926-3136.
“We are hopeful that we’ll be in a better place in late summer,” Di Salvo said. “But it’s way too early to say.”