Days after a deadly, contagious form of bird flu was found on a Lancaster County poultry farm, Don Ranck spoke to a farmer who was open about the fear he felt every time a wild bird flew over his chicken coops.
According to Ranck, vice president of the Lancaster County Farm Bureau, the farmer feared that any wild bird that flies over could become infected and contaminated droppings could spread the disease to his flock.
“There are so many unknowns. There are so many ducks flying over and they can all carry it,’ Ranck said.
In fact, scientists say they believe the virus — a strain of bird flu that is highly deadly and contagious in poultry — made its way to the United States through wild waterfowl that migrated from Europe.
Now, while much of the spring waterfowl migration season has ended in Pennsylvania, local experts believe the virus has likely spread to and circulates within some of the state’s native bird species year-round.
This means that local poultry farmers must remain vigilant to limit their flocks’ exposure to wild birds.
“We don’t know how soon it will be before this particular outbreak is resolved,” said Andrew Di Salvo, a wildlife veterinarian with the state’s Wildlife Commission.
Not closely monitored
On Tuesday, the virus was discovered in just eight Pennsylvania wild birds — two bald eagles, five merganser ducks and one red-headed 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, 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 are likely deceptive, Di Salvo said.
“Our wildlife health surveillance is not uniform across the Commonwealth,” he said in an email, explaining that it is much more difficult to track sick birds in remote areas. “It’s very biased about where people live because 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 on record nationwide, including hundreds of infections along the East Coast.
Highly pathogenic avian influenza had been detected in at least 899 wild birds in 34 states on Wednesday, according to figures from the U.S. Centers For Disease Control and Prevention.
Again, Di Salvo offered perspective when it comes to business in Pennsylvania.
“If we don’t test birds in an area, that doesn’t mean the disease isn’t there. … It is much more accurate to assume that the disease is common in wild birds throughout the Commonwealth,” he said.
Waterfowl are among the species considered highly susceptible to the current avian flu outbreak, and recent migrations through the area have put agricultural officials on edge.
Avian influenza is most commonly spread when healthy birds come into contact with bodily fluids from other infected birds, wild or domestic, experts say.
According to a pair of biologists at Millersville University, this kind of contact has likely occurred between local wild birds since the current strain of bird flu was first confirmed in the United States in December.
For example, a virus-positive duck may have had its feces 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 eaten an infected bird that migrated through the area, contracting the disease in the process, said Aaron Haines, an associate professor of conservation biology who specializes in wildlife management.
“Eagles are here all year round and they feed on waterfowl,” he said. “I think there’s potential for further spreading among our local birds here.”
That’s a problem for poultry and egg farmers, agricultural officials say, because infected wild birds can fly over and land near chicken coops and other facilities. There they can directly infect poultry, including chickens, ducks, geese, quail, pheasants, guinea fowl and turkeys. Or the wild birds may secrete bodily fluids that contaminate farmers’ clothing and equipment, which later transmit the virus to poultry.
Wild birds more robust
Because of those threats, experts have encouraged backyard farmers and poultry farmers to adopt biosecurity measures to protect their flocks. They include limiting non-essential access to farms; regular cleaning of farm-related clothing and equipment; do not share equipment with other farms; and stepping up decontamination of staff and vehicles on farms.
Still, the virus was found Thursday afternoon in flocks of six Lancaster County poultry farms, killing 3,825,800 birds — a combination of laying hens, meat birds and pullets. Nationally, the disease had infected 247 flocks in 29 states, with 35.52 million commercial or backyard poultry, according to the U.S. Department of Agriculture.
Most of those birds were mainly euthanized in an attempt to stop the further spread of the virus. Killing the birds is also considered more humane than letting poultry suffer from the flu.
“You get serious breathing problems,” Ryndock said, referring to the disease in poultry.
In birds, symptoms include impaired coordination, diarrhea, runny nose, decreased or abnormal egg laying, lack of energy, lack of appetite, and even sudden death.
However, Haines said wild birds seem more “robust,” or better able to handle the disease, meaning symptoms can be less severe, allowing them to move more easily while infected.
That’s probably already the case, according to Sean Murphy, a state ornithologist at the Game Commission.
“It’s there on our landscape,” Murphy said.
Murphy emphasized that point, naming just a few of the native wild bird species he knows are susceptible to the disease, including predators such as red-tailed hawks, great horned owls, bald eagles and Cooper’s hawks.
“There are plenty that are here all year round,” he said.
If there’s any good news, it’s that many migratory waterfowl have already disappeared from the area and temperatures are starting to rise, multiple experts said.
“Disease transmission should decrease as bird density decreases, and this virus cannot survive for long at room temperature or above,” said Di Salvo, the committee’s veterinarian.
Rydnock added that humid summer air will make it more difficult for airborne virus droplets to travel
However, humidity and changing temperatures will have little impact on transmissions from direct contact with bodily fluids such as feces from infected birds, he said.
“I think that could be a factor that will keep it going through the summer,” Rydnock said.
Dan Ardia, a biology professor at Franklin & Marshall College, agreed, especially when it comes to infections in poultry houses, where the climate is at least somewhat under control and birds are often huddled and crammed together, causing stress that feeds the can lower the immune system.
“Housing conditions don’t change from year to year, month to month,” Ardia said.
In rare cases, people have contracted bird flu, but experts, including the CDC, have said this outbreak poses a low risk to humans.
Earlier this spring, commission officials said people should exercise caution when handling wild birds.
“Always look for wildlife from a safe distance. Avoid contact with surfaces that may be contaminated with wild or domestic bird feces. Do not handle wildlife unless you hunt, capture or are otherwise authorized to do so,” officials said, adding that even those authorized to handle wildlife must wear personal protective equipment.
Previously, committee officials have asked people who encounter sick or dead wild birds to report it at 610-926-3136.
“We are hopeful that we will be in a better place in the late summer,” said Di Salvo. “But it’s way too early to say.”