Avian flu spreading in Louisiana, wildlife experts report

Louisiana birds are getting sick as a strain of the avian flu sweeps across the state, experts say, but getting hard numbers for the outbreak is tough.

H5N1, a strain of avian influenza, has returned to the state for the second year in a row. It's been carried in by migratory birds and threatens both ducks and domesticated poultry, experts warn. Evidence of the outbreak is anecdotal, based on calls and veterinarian findings, because these numbers aren't tracked well.

Even without the numbers, experts are confident enough that the virus is back in force, and with a 100% kill rate among domesticated poultry, they put out warnings to the public about the threat of the illness.

"That's the biggest unknown of this thing is nobody knows," Research Program Manager for the Louisiana Department of Wildlife and Fisheries Paul Link said of the exact numbers. "It looks like it's mostly affecting the juveniles, though it's higher this winter. It's the same strain that's affecting the birds again this year as last year, which is a first for any of these outbreaks."

The illness can infect humans, though it is rare. The Center for Disease Control reported a few cases of human infection. Two were fatal, both in Cambodia, and only one was reported in the United States, in Colorado.

Officials with the Louisiana Department of Wildlife and Fisheries suggest avoiding potentially ill birds or their remains.

If a dead bird is found and poses a risk to others, pets, or needs to be removed for any reason, wear gloves, a cloth mask if available, and double bag the carcass, said Louisiana Department of Wildlife and Fisheries Assistant State Wildlife Veterinarian Rusty Berry. Wash hands or any other parts of the body potentially exposed to the bird as well, he added.

"If you want to dispose of it, just make sure you dispose of it with gloves, and maybe, you know, a lot of people still have masks leftover from COVID that they could use," Berry said. "You have to remember how these viruses work, I mean they are constantly replicating… so the issue is that a person can get it and then, well, it starts replicating in people. That's when an epidemic or pandemic can happen."

Louisiana Department of Wildlife and Fisheries doesn't keep a count of the H5N1 infections but the United States Department of Agriculture does. Their website lists 153 cases in Louisiana since Oct. 19, 2022.

The Center For Disease Control and Prevention also tracks the infections and also lists 153 in Louisiana since Dec. 16, 2022. As of Dec. 13, 2023, the CDC has the number of wild bird infections in the United States at 8,494 and poultry at nearly 77 million.

The poultry numbers are so high because their immune systems are not as developed as wild fowl, Woodruff said. As soon as the virus is found in the flock, the entire flock is culled and their living quarters must be cleaned. This was a factor in the skyrocketing egg prices last year.

Link said the virus likely has flown in with Arctic Nesting Geese such as Lesser Snow Geese and Greater White Fronted Geese.

Last year when the virus arrived, mass die-offs were reported around the state. Researchers like Link were documenting hundreds of dead birds a day for about five days in the beginning of December 2022. According to the CDC, in November of last year, 49 million birds across 46 states had either died from or were culled due to infection.

This year, there have been no mass die-offs in Louisiana, Woodruff said. While there are no die-offs, Link said, what's odd is that the same group of birds are falling ill again to the exact same strain.

"Normally it's a different strain, and it kind of goes away… and it doesn't reinfect, so this is the first time that it's ever the same strain that's reinfecting the same flock and this year we're seeing about 20% to 25% adult mortality," he said. "So it seems to be a little bit more serious strain this year than previous years and we don't really quite know why."

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Researchers divide ducks up into two categories: dabblers and divers. Dabblers are those most commonly hunted, and Link said last year 98% of those found dead were juvenile. This year 75% of them are juvenile and 25% are adults

This is strange, Link said, because the antibodies from survivors last year would have likely made the birds more resilient this year; however, the percentage of adults dying of the illness has risen.

The number of factors at play, said Link, is too vast to know exactly why adults are dying off more, but it could be as simple as less food. The drought that has been affecting Louisiana stunted vegetation growth and that means leaner ducks. Less calories could mean a weaker immune system, he said, or it could also be that the birds are tuckered out because they have to fly farther to find more food.