From a distance, the Gladys Porter Zoo is monitoring an alarming spread of avian flu affecting poultry farms across the United States.
So far, no zoo animals in North America have been affected by the highly contagious virus, but zookeepers across the United States have been vigilant in monitoring the developments as avian influenza has been reported at several poultry farms, including a recent infection in Texas.
“I would say I’m very attentive, paying a lot of attention to the situation, particularly if it turns out closer to us,” said Dr. Thomas deMaar, senior veterinarian at the Brownsville zoo. “We are keeping some of our animals inside, but we cannot keep them all inside, and we are not concerned yet because the disease is not near us as far as we know.”
Similarly, other zoos are watchful and cautious. According to an Associated Press report this week, North American zoos have already begun measures to protect their birds by reinforcing and expanding enclosures or bringing specimens indoors and away from potential exposure.
The disease infects, poultry and waterfowl—sometimes even mammals—and can be spread by wild birds that include ducks, shorebirds and gulls, according to the U.S. Department of Agriculture.
The avian influenza is highly contagious and potentially deadly, prompting official government orders to kill stock that have been infected. The AP reported infections have resulted in the ordered killings of nearly 23 million birds at U.S. poultry farms in attempts to curtail the spread of the virus.
“There really is no cure or remedy,” deMaar said. “It’s a virus.”
However, the U.S. Department of Agriculture has indicated that zoos might be able to avoid that by isolating infected birds and possibly euthanizing a small number of them, the AP reported. Further, deMaar said such a drastic measure has never happened before for a zoo.
“That has never happened,” deMaar said. “The USDA is very much aware of the value of our collection of birds. Nor do we know if every species of bird is susceptible to avian influenza. So their (the USDA’s) approach would be to test the birds first.”
For now, the Brownsville zoo remains far removed from the virus. So far, the closest infected poultry farm has been in Erath County, near Stephenville, less than 80 miles southwest of Fort Worth, where the USDA reported 1,649 birds were infect April 2.
“So as the veterinarian, I am monitoring the USDA website,” deMaar said.
However, the zoo’s birds will remain on display, the veterinarian explained.
“It’s not that zoos are putting animals away from the public. That’s not the point. That’s a misunderstanding,” deMaar said. “Zoos where the disease is prevalent are trying to keep animals indoors to prevent them from having contact with wild birds. Because that’s how the transmission is, typically, from other birds like wild ducks.”
There is a slight concern about backyard poultry being infected in the Rio Grande Valley, deMaar suggested.
“We have issued an advisement to all of our staff: If anyone has any chickens at home, they probably ought to look to keeping them (cooped up) and not letting them wander around the yard. That’s the best you can do. If you see wild ducks approaching your chicken coop, you probably need to create some sort of secondary perimeter.”
Such quarantine and movement controls match the advice from the USDA for anyone raising poultry at home.
The USDA says infected birds might experience sudden death, but other symptoms include lack of energy and appetite; decreased egg production; misshapen or soft shells in eggs; swelling in the head, comb, eyelids, wattles and hocks; purple discoloration in the wattles, comb or legs; nasal discharges, coughing and sneezing; or diarrhea.
“In the poultry market, this is of great concern because their profit margin is very slim,” deMaar said.
However, for zookeepers, the potential for concern is centered on preserving endangered species and tending to individual specimens.
Avian influenza exists in two forms—low pathogenic and high pathogenic. According to deMaar, the low-pathogenic version is common in wild ducks, but it’s the highly virulent version that causes sickness and deaths in chickens and turkey and that has the poultry industry, the USDA, and now zookeepers on guard.
Although zoos to the north might have the option to bring birds indoors to guard against avian flu, that is a challenge for the Brownsville zoo, deMaar said.
“The challenge is that with a lot of zoos up north where this is occurring, they also have a thing called winter,” deMaar explained. “So they have places to put birds that are indoors because they do so every winter. We don’t have that issue really, so we have the big walk-through aviary. We really have no place to put (the zoo’s other birds) away somewhere, like the cassowaries. We can’t keep them indoors.”
The threats to zoo birds presented by winter freezes in Brownsville pass quickly—as do hurricanes and major storms.
“It’s overnight. A hurricane is an event and then it passes. The aviary will stand hopefully,” deMaar said. “The cassowaries do have a barn they come in to every night, but (avian flu) would not be an overnight event. If we are pulling them inside, we are pulling them inside until it blows over.”
Yet, summer heat and blaringly hot temperatures are bringing optimism to the vigilance. Outside of a host, viruses tend to die quickly when exposed to hotter temperatures, deMaar said.
“With the weather getting hotter, there’s a hope the disease might peeter out,” deMaar said. “That’s the hope.”
