Avian flu threat means suburban zoo, rehab centers have to hide their precious birds
Peacocks usually are free to roam the grounds of Brookfield Zoo, putting on courtship displays this time of year.
That seasonal ritual, when male birds fan out their jewel-colored feathers to impress females, won't have an audience of zoo visitors this spring.
Brookfield has moved peafowl and guinea fowl indoors to isolate them from contact with wilds birds that can spread a highly infectious and deadly form of bird flu. Storks, cranes, crows and Cape Barren geese also are staying in their indoor holding areas away from the public eye.
The bird flu outbreak sweeping through poultry farms and backyard flocks across much of the United States has put zoos and animal rehabilitation centers on high alert.
"We want to take all the precautions that we can," said Dr. Sathya Chinnadurai, senior vice president of animal health and welfare at the Chicago Zoological Society, the nonprofit that operates Brookfield Zoo.
As of Monday, 28.2 million birds in commercial and backyard flocks have either died from the disease or been euthanized to prevent further spread of the virus, according to the U.S. Department of Agriculture. The first U.S. case appeared in a wild American wigeon duck in South Carolina in January.
The last major outbreak of highly pathogenic bird flu wiped out 50.5 million commercial birds, primarily chickens and turkeys, from December 2014 to June 2015, costing the U.S. economy an estimated $3.3 billion, the USDA said in a final report.
"Now, that outbreak mainly hit the poultry system. This outbreak is 100% hitting the poultry system. But it seems to be hitting wild populations harder than the previous one," said Dr. Sarah Reich, head veterinarian at Willowbrook Wildlife Center in Glen Ellyn.
Cook County Forest Preserve biologists suspect bird flu caused the recent deaths of more than 200 double-crested cormorants at a lake and man-made rookery in Barrington, though federal authorities have yet to confirm positive cases.
So far, 763 cases have been detected among wild birds in more than 30 states. The outbreak has claimed at least 41 bald eagles from Maine to Florida.
"It's really bigger, and in 2014-15, I don't recall any large-scale mortality events in wild birds," said David Stallknecht, director of the Southeastern Cooperative Wildlife Disease Study, a research organization at the University of Georgia. "There were raptors affected and some other species and some geese, but nothing like the numbers we're seeing now."
Virus precautions
Two U.S. zoos have had cases of highly pathogenic bird flu in birds in their collection, according to the USDA. Bird flu viruses are classified as low pathogenic or highly pathogenic based on their genetic features and the severity of the disease in poultry.
The USDA does not track or report cases in zoos, but the agency's Animal and Plant Health Inspection Service tests and confirms samples if requested. Zoos then work with state animal health officials to determine quarantine or isolation requirements, a USDA spokeswoman said.
Infected birds can shed the virus through droppings and respiratory secretions. Zoos have taken strict measures to avoid inadvertently transmitting the virus through contaminated equipment and supplies. Brookfield has added boot scrubbing and disinfection stations for caretakers of birds housed indoors.
"We really want to make sure that we're reducing the risk of any fecal material or anything else being tracked in from wild geese or on any other wild birds into the indoor buildings," Chinnadurai said.
Condors and some of the other larger birds at the zoo remain outside. The zoo has put tarps or covers over their outdoor enclosures to try to keep out wild birds.
"Those are animals that we feel it's in their best welfare for them to stay in their larger outdoor access habitats," Chinnadurai said.
While the disease often is fatal in chickens and turkeys, wild species of migratory waterfowl and shorebirds can carry the virus without being sickened by it.
"They can almost be like typhoid Marys where they can spread the disease but they aren't necessarily clinically showing signs of disease," Reich said.
Willowbrook nurses injured and orphaned wildlife back to health, and it's one of the few rehabilitation centers licensed to accept injured migratory birds in the Chicago area.
"We haven't cut capacities or stopped taking in certain species like some other centers have," Reich said.
But should cases start to rise in Illinois, Willowbrook experts fear having to limit the intake of certain species heading into peak migration season.
"We are right at the cusp of orphan gosling and duckling season, too, and we take hundreds and hundreds of goslings and ducklings," Reich said. "And the first species or group of animals that we would limit intake for would be waterfowl because they are the highest-risk, and it would be devastating because it could mean that hundreds to thousands of birds wouldn't get potential care."
The risk to the public's health from H5N1 bird flu viruses remains low, but job-related exposures to birds may put people at higher risk of infection, the Centers for Disease Control and Prevention has said.
Willowbrook employees who care for vulnerable species wear personal protective equipment and do "lots and lots and lots of disinfection," Reich said.
"We don't really have a lot of different areas that we can isolate animals into, so we really try to limit things spreading from the start," she said.
If high-risk species are brought to Willowbrook with neurological or respiratory issues - potential signs of avian flu - and those problems can't be attributed to another cause, birds will be euthanized. A Great blue heron and lesser scaup duck have been among the handful of birds that have died on their own or been euthanized at Willowbrook, which hasn't pursued testing.
"If we had some sort of event where multiple birds came in showing clinical signs from the same area," Reich said, "or if God forbid, animals already in our care started showing those signs when they didn't have them before, that's when we would elect to send those individuals in for testing."
'Expecting anything'
Some wildlife experts say it's unclear when the outbreak could subside or if this form of bird flu could continue to circulate.
"Our caseload, at least the number of submitted cases is going down, at least from the Southeast, which may be a good sign. But I guess we're just sitting here expecting anything," Stallknecht said. "I don't know how else to say it."
Transmission of low pathogenic strains of bird flu in North America generally picks up again in the late summer or early fall, he said.
"That's what we need to wait on to see what's going to happen. In Europe, this virus evidently is maintained in wild waterfowl populations," Stallknecht said. "It certainly is a possibility here."
Bird flu tends to come in cycles, Brookfield's Chinnadurai said.
"As birds are migrating north, we're keeping a close eye on their movement," he said. "Likely based on the seasonality of wild bird migration, it might be another month or two before we start to see a downswing."